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Citation: Lorente-Mento, J.M.;
Valverde, J.M.; Serrano, M.; Pretel,
M.T. Fresh-Cut Salads: Consumer
Acceptance and Quality Parameter
Evolution during Storage in
Domestic Refrigerators. Sustainability
2022, 14, 3473. https://doi.org/
10.3390/su14063473
Academic Editor: Flavio Boccia
Received: 28 February 2022
Accepted: 13 March 2022
Published: 16 March 2022
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sustainability
Article
Fresh-Cut Salads: Consumer Acceptance and Quality ParameterEvolution during Storage in Domestic RefrigeratorsJosé M. Lorente-Mento 1, Juan M. Valverde 2 , María Serrano 1 and María T. Pretel 1,*
1 Department Applied Biology, University Miguel Hernández, Ctra Beniel, km 3.2, Orihuela,03312 Alicante, Spain; [email protected] (J.M.L.-M.); [email protected] (M.S.)
2 Department Food Technology, University Miguel Hernández, Ctra Beniel, km 3.2, Orihuela,03312 Alicante, Spain; [email protected]
* Correspondence: [email protected]
Abstract: Ready-to-eat fresh-cut salads (RTESs) are fresh-cut vegetables that have been minimallyprocessed and remain alive until consumption. A survey with 297 respondents was performed,showing that most respondents consumed RTESs composed of various vegetables once or twice aweek. The most important items for consumers’ RTESs purchasing intention were the expirationdate and the absence of exudates and brown and dehydrated leaves, while after storage in domesticrefrigerators, the most important item for consumption refusal was the presence of strange odours.On the other hand, among the non-consumers of RTESs, the most important reason for not buyingthis kind of produce was the use of plastic packaging. Microbiological analysis of RTESs (composedof corn salads, radicchio and escarole leaves) showed that moulds, yeasts and psychrophilic aerobicmicroflora remained unchanged from buying to the expiration date, while increases occurred inmesophilic aerobic microflora, although all of them were within safety levels for consumption evenafter 4 days of the expiration date. Finally, total phenolics and antioxidant activity were higher incorn salads followed by radicchio and escarole leaves, and generally, no significant changes occurredin the bioactive compounds of RTESs during storage in domestic refrigerators.
Keywords: browning; spoilage; phenolics; antioxidants; radicchio; escarole; corn salad
1. Introduction
Eating habits have changed in industrialised countries mainly due to the reducedtime available for food preparation and the emerging consumer’s demand for healthy andtime-saving dietary solutions [1–4]. In this sense, the consumption of ready-to-eat salads(RTESs) has increased noticeably in the last years in developed counties since consumersperceive them as fresh, safe, nutritional and healthy products, which can be consumedwithout preparation, are 100% edible and socially appreciated as save-time and very high-quality products [4–8]. RTESs are minimally processed products. Their processing includesthe selection of the plant material, cutting, washing, drying and packaging in plasticcontainers [9], which should be performed under highly hygienic conditions in order toavoid microbiological contamination during processing [10,11]. RTESs maintain sensorial,nutritional and microbiological quality for 5–7 days when stored at 4–6 ◦C in domesticrefrigerators, their shelf life being shorter than the raw products [4,12,13].
Quality losses in RTESs are mainly due to microbial growth, which is increased by juicecellular leakage as a consequence of the cutting process [11,14–16]. Vegetables growingare inevitably contaminated by microorganisms present in soil and irrigation water, whichcan get internalised in the plant’s body, and contamination can also occur during each stepof the production chain [17,18]. According to European Regulation (EC) No 1441/2007,concentrations of Listeria monocytogenes lower than 100 colony-forming units (CFU) perg and the absence of Salmonella spp. are essential criteria to define the safety of RTESsduring their shelf life. There are no mandatory microbiological criteria for total aerobic
Sustainability 2022, 14, 3473. https://doi.org/10.3390/su14063473 https://www.mdpi.com/journal/sustainability
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mesophilic and E. coli, although several guidelines recommend as acceptable CFUg−1 lowerthan 106 and 102, respectively [19,20]. Browning and oxidation of the cut surfaces are otherfactors responsible for RTES quality losses [1,12,21]. Moreover, nutritional and functionalquality losses also occur during the storage of RTESs. The functional properties of vegetableproduce are due to bioactive compounds, such as fibre, phenolic compounds (phenolic acidsand flavonoids), terpenes, phytosterols and carotenoids, among others [21–23]. Phenoliccompounds have the ability to scavenge free radicals, acting as antioxidants with importantbenefits for reducing cell oxidative stress and leading to preventing degenerative diseasedevelopment [23,24].
On the other hand, RTESs are expensive compared to the original products, beingaffordable for medium–high purchasing power consumers [5,6]. In some previous reports,key points and factors during RTES processing to obtain high-quality products have beenaddressed [1,10,25]. However, as far as we know, no information is available in the literatureregarding factors determining consumers’ purchasing behaviour of RTESs, their consump-tion patterns and frequencies and the evolution of RTES quality properties during storagein domestic refrigerators. Thus, this research aims to determine the most important reasonsinfluencing and dissuading consumers in purchasing RTESs by surveying 297 respondents.The survey results could be useful to the industry by permitting the development of newproducts according to consumers’ preferences. In addition, microbiological, sensory andfunctional quality properties were evaluated during storage in domestic refrigerators in acommercial RTES composed of corn salads, escarole leaves and radicchio.
2. Materials and Methods2.1. Survey of Consumers of RTESs and Ethical Standards Disclosure
The questionnaire aimed to assess Spanish people’s regularity in consuming RTESsalongside the reasons underlying their consumption patterns. This study was conductedaccording to the guidelines laid down in the Declaration of Helsinki, and all proceduresinvolving research study participants were approved by the Ethics Committee of theUniversity Miguel Hernández (reference DBA.MPP.01.21). The participants’ consent wasasked for in a previous contact, and the questionnaire was sent only to participants whoindicated their positive consent to participate in the survey. The personal features of therespondents (gender, age, purchasing power according to residence, education level andmonthly income) were taken under principles of anonymity and confidentiality, and thedata obtained were used exclusively for the present study. The questionnaire was madewith Google Forms, and responses from 297 participants, whose personal characteristicsare shown in Table 1, were received. Most of the participants (44.3%) were 36–50 yearsold, followed by 30.7% of the participants who were 51–65 years old, while less than 30%were between 18 and 35 years old. More than 70% of the participants lived as a couplewith or without children, had high education levels and had a permanent job. Four ofthe respondents were unaware of RTESs’ existence. These respondents were omittedfrom the survey. Sixty-nine were not consumers of freshly cut salads. Accordingly, theseparticipants were asked about the level of importance (none, little, medium, quite and verymuch) they attached to different reasons for no consumption of RTESs (Questionnaire is inSupplementary File). The remaining 224 respondents were consumers of RTESs and wereasked about their frequency of consumption and the type of salads they consumed (singleingredient, several ingredients and both types). In addition, the value of different aspectsby consumers when buying and consuming RTESs (none, little, medium, quite and verymuch) was evaluated (Questionnaire is in Supplementary File).
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Table 1. Characteristics of the participants in the survey (n = 297).
Characteristic Percentage (%)
GenderFemale 55.7Male 44.3Age
18–24 6.825–35 15.936–50 4451–65 31
Older than 65 2.3Educational levelPrimary school 2.7
Secondary school 7.8Technical education 12.5
University 77Marital status
Couples with children 53.6Childless couples 21.2
Single-parent family 6Single without children 19.2
EmploymentStudent 7.1
Employed (permanently) 73.6Employed (temporary) 12
Unemployed 5.1Pensioner 2.2
Consumer of minimally processed saladsConsumer 75.7
Non consumer 24.3
2.2. Plant Material
RTESs from a commercial brand composed of corn salads (Valerianella locusta L.),escarole leaves (Cichorium endivia L.) and radicchio (Cichorium intybus L) were purchased ata supermarket on the same day as delivery. They were transported to the laboratory in athermic bag and stored in a domestic refrigerator. Three RTES bags were taken at day 0(purchasing day) and after 4, 7 (one day after the sell-by date) and 11 (5 days after sell-bydate) days of storage. The refrigerator was opened several times a day to simulate realconditions, and the temperature ranged from 4 to 7 ◦C.
2.3. Microbiological Analysis
Microbiological analyses were performed according to Sanchez-Bell et al. [26]. Briefly,a 10 g sample of each salad was homogenised with 90 mL of sterile peptone water for 2 minin a sterilised blender. Serial dilutions (1:10) were aseptically made from the homogenate,under the laminar flow hood, and inoculated on the different plates. Total mesophilicmicroorganisms were counted in Petri dishes filled with agar (PCA) and incubated at 30 ◦Cfor 48 h. Moulds and yeasts were counted in Petri dishes filled with Rosa de Bengala (RBA)incubated at 25 ◦C for 5 days. Psicrophilic microorganisms were counted in PCA incubatedat 5 ◦C for 10 days. Data are expressed as log CFU g−1 and are the mean ± SE of three bagsor replicates.
2.4. Determination of Total Phenolic Compounds and Antioxidant Activity
Total phenolic content and antioxidant activity were measured in each vegetableingredient of RTESs independently: corn salads, radicchio and escarole, the last one beingseparated into white and green leaf portions. Extractions were performed by homogenising5 g of tissue with 10 mL of methanol:water (8:2) by using a mortar and pestle. Theextracts were centrifuged at 12,000× g for 15 min at 4 ◦C, and the supernatant was used
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to quantify total phenolic content with Folin–Ciocalteu reagent, as previously describedby Serrano et al. [27]. Supernatants were also used to quantify total antioxidant activity byusing horse-radish-ABTS-H2O2 assay, according to Asencio et al. [28].
2.5. Sensorial Analysis
A semi-trained panel of 5 judges performed the sensorial analysis on each independentingredient of RTESs. For each one, judges evaluated decay symptoms, browning, firmness,dehydration and overall appearance on a scale from 0 (dislike extremely) to 10 (like ex-tremely). Judges had at least one year of experience evaluating fresh vegetable productsand were previously pre-trained on the parameters to be evaluated in these RTESs.
2.6. Statistical Analysis
Data of evaluated parameters during storage were submitted to an analysis of vari-ance (ANOVA) by using the SPSS software version 20 (SPSS Inc., Chicago, IL, USA), anddifferences at p < 0.05 were considered significant. In the figures, LSD values are shown.
3. Results and Discussion3.1. Responses to the Questionnaire
The survey revealed that 4 out of the 297 respondents did not know of RTESs’ existence,69 did not consume them, and 224 were consumers of these prepared salads. The mainreason given for not consuming RTESs was related to environmental issues, since 79.7% ofthe respondents gave between medium and very much importance to the use of plasticfilms in the packaging of RTESs (Table 2). The following reason for no consumption, statedby 58% of consumers, was that they thought these products were not as healthy as wholevegetables, and they gave medium (31.9%), quite (11.6%) or very much (14.5%) importanceto this item. However, more than 40% of the consumers gave none or little importanceto price, and thus, although RTESs are more expensive than whole products, this higherprice is not the main reason for not consuming these products. Finally, the appearanceof the product was not an important reason for consumption either, since 76.7% of theconsumers rated this as having no, little or medium importance (Table 2). In agreementwith our results, Dinnella et al. [29] reported that respondents gave more importance tothe use of environmentally friendly packages in fresh-cut salads than to their sensorialproperties. According to the present results, a sector of the Spanish population thinksthat fresh and whole vegetables are healthier than RTESs and that plastic packaging ofRTESs is not environmentally friendly, being the main reasons discouraging them to buythese kinds of products. However, these RTES disadvantages could be reduced if clearinformation regarding safety, nutritional and health properties of the cut vegetables andthe environmental impact of the packaging were provided in RTESs labels, as previouslysuggested by other authors [29–31].
On the other hand, 224 out of the 297 participants (75.7%) were consumers of RTESs,and among the RTES consumers most of them ate RTESs once or twice a week. RTESscomposed of a mixture of ingredients were consumed by 56.5% of the respondents, althougha high percentage of them (38%) were consumers of both types of RTESs, with single orvarious ingredients (Table 3). Thus, consumers of RTESs are used to regularly eating thesekinds of products, as usually occurs with other foods [29,32–35].
With respect to the level of importance (none, little, medium, quite and very much)that consumers gave to different items at the time of purchasing RTESs, results showedthat 85.7 and 76.3% of the respondents gave medium to very much importance to the mixof ingredients and price, respectively (Table 4). In addition, it is worth noting that mostconsumers (ca. 70%) gave no or little importance to the presence of dressing and cutlery inthe package of RTESs, while 71.9% gave medium to very high importance to the amountof plastic in the packaging of RTESs. Moreover, a high percentage of consumers (57.1%)scored the content of bioactive compounds in RTESs as quite or very much important,showing that they are aware of the beneficial health effects of vegetable consumption,
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either as fresh products or in RTESs. On the contrary, no consumers of RTESs thought thatfresh vegetables are healthier than RTESs, which could be related to the education levelsof consumers.
Table 2. Level of importance (none, little, medium, quite, very much) that consumers give to differentaspects. Answer to the question: Why are you not a consumer of minimally processed salads?(n = 69).
Answer None (%) Little (%) Medium (%) Quite (%) Very Much (%)
Price (they are very expensive) 14.5 27.5 31.9 11.6 14.5Fresh produce is healthier 13.1 21.7 14.5 27.5 23.2
I don't like their appearance 21.7 33.3 21.7 14.5 8.8The use of plastics in packaging 7.2 13.1 18.8 23.2 37.7
Table 3. Frequency of consumption and type of fresh-cut salads that consumers usually buy (n = 224).
Characteristic Percentage (%)
Frequency of consumptionLess than 1 time/month 8.5
1–2 times/month 28.51–2 times/week 403–4 times/week 17
Daily 6Type of salad you eat
Single ingredient 5.5Various ingredients 56.5
Both types 38
Table 4. Level of importance (none, little, medium, quite, a lot) that consumers gave to differentaspects of RTESs at purchasing and consuming times (n = 224).
Answer to the Consumer of MinimallyProcessed Salads None (%) Little (%) Medium (%) Quite (%) Very Much (%)
Time of purchase of the fresh-cut saladsVariety of ingredients 2.7 11.6 20.1 40.2 25.4
Price 6.7 20 32.6 29.9 13.8Accompaniment of dressing and cutlery 37.5 31.7 14.3 8.5 8.0
Amount of plastic it contains 9.8 18.3 29.9 16.1 25.9Bioactive compounds 5.8 13.8 22.3 25.9 31.3
Date of expiration 1.3 6.3 8.9 26.3 53.6Presence of exudates 2.7 8.0 8.5 19.2 61.6
Presence of brown leaves 2.3 6.7 6.3 18.3 66.5Presence of dehydrated leaves 1.8 5.8 3.1 18.8 70.5
Time to consume the fresh-cut salad afterseveral days stored in the refrigerator
Date of expiration 3.1 10.7 19.2 26.3 40.6Presence of strange odours 0.9 5.4 4.0 18.3 71.4
Presence of exudates 1.8 5.4 7.1 19.6 65.2Presence of brown leaves 0.9 5.8 10.3 25 58.0
Presence of dehydrated leaves 1.3 6.3 7.6 25 59.8
Expiration date and appearance (presence of exudates and brown and dehydratedleaves) were the most important items determining consumers’ RTESs purchase intention(Table 4), in agreement with Dinnella et al. [29]. Thus, the expiration date was considered asquite (26.3%) or very much important (53.6%), and the presence of exudates and brown anddehydrated leaves was rated as very much important by 61.6, 66.5 and 70.5% of consumers,respectively (Table 4). Accordingly, Ares et al. [12] showed that these quality traits were the
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most important factors responsible for consumers’ rejection of lettuce RTESs at the timeof purchasing. However, the scores given by consumers to these quality traits for RTESconsumption after storage at home were different. Thus, the expiration date had scoredlower than at the time of buying and scores for the presence of exudates and brown anddehydrated leaves decreased almost ten points (Table 4). It is worth noting that the mostimportant aspect for refusing RTES consumption was the presence of strange odours, forwhich most of the respondents (71%) gave very much importance.
In general, the results showed that consumers were more exigent of the high-qualitytraits of RTESs at the time of buying than at the time of consumption. In fact, with respectto the question “Would you buy the salad if any of the valued aspects failed?” 64.4% wouldnever buy the RTESs while 50.3% would never eat them (Table 5). However, just 4.3% of therespondents were worried about wasting food and would be able to consume RTESs evenif any of the quality traits failed, which is a surprising result contrasting with the awarenessfor environmental issues addressed by respondents regarding the use of plastics in RTESs.Thus, consumers seem not to associate waste of food with environmental risks, accordingto previous reports [36–38] despite the fact that this is one of the most important factors forreducing human environmental impact [34,35,38–41]. Nevertheless, the waste of fresh-cutsalads could be reduced if consumed as soon as possible after buying [42]. Finally, 23.9% ofconsumers would buy RTESs even if any of their quality traits failed depending on price,expiration date and overall appearance (Table 5), which would justify a discount on theseproducts being offered by supermarkets when they are close to the expiration date.
Table 5. Question addressed to consumers about whether they would buy/consume fresh-cut saladsif any of the assessed aspects failed (n = 224).
Answer to the Question Percentage (%)
Would you buy the salad if any of the valued aspects failed?Yes. It depends on the price 1
Yes. It depends on the aspect 9Yes. It depends on the expiration date 1.7
Yes. It depends on the price, the appearance and the expiration date 23.9Never 64.4
Would you eat the salad if any of the valued aspects failed?Yes. I don't want to waste food 4.3
Yes. It depends on the expiration date 4.3Yes. It depends on the appearance of the product 41.1
Never 50.3
This survey pointed out that consumers gave high importance to the properties ofthe RTESs related to sensory, nutritional and health beneficial effect aspects. Thus, anexperiment was performed to evaluate the evolution of some of these properties in RTESsduring storage in a domestic refrigerator.
3.2. Evolution of Quality Parameters of RTESs in a Domestic Refrigerator3.2.1. Microbiological Quality
Counts for moulds and yeast were 4.27 ± 0.24 log CFU g−1 at day 0 and remainedwithout significant changes (p > 0.05) until day 7 (one day after the expiration date), in-creasing up to 5.38 ± 0.33 log CFU g−1 at day 11. Marinelli et al. [14] reported an increaseof 2 log CFU g−1 in moulds and yeast count in ready-to-eat salads during nine days ofstorage, although initial values were higher than those found in the present experiment,showing that sanitising operations are significant tasks to preserve microbiological qualityin RTESs. The major fungi species identified in RTESs have been reported to be Cla-dosporium, Penicillium, Alternaria and Geotrichum spp., with percentages of 35%, 20%, 15%and 15%, respectively, being the primary fungi responsible for inducing decay in a fewdays [15]. Ramos et al. [10] reported that the count of total mesophilic microorganisms
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in recently packaged RTESs was 103–106 CFU g−1 and very similar (103–109 CFU g−1)when they arrived at the supermarket or sale point [10]. Accordingly, Arienzo et al. [9]reported that 100% of the samples of baby leaves in ready-to-eat salads displayed morethan 6 log CFU g−1 for total mesophilic microorganism on the packaging date, increasingup to 7.5 CFU g−1 at the expiration date. Therefore, measures of the CFU of total mesophiliccould be a good tool to evaluate sanitary conditions in RTESs during processing. In thepresent experiment, counts for total mesophilic microorganisms were 4.54 ± 0.76 CFU g−1
at day 0 and increased significantly (p < 0.05), up to 6.22 ± 0.37 and 6.47 ± 0.28 CFU g−1,after 7 and 11 days of storage, respectively (Figure 1). However, counts for total mesophilicwere at acceptable levels and safety for consumption, according to Ramos et al. [10],Miceli et al. [43] and Manzzoco et al. [42], even three days after the expiration date. Accord-ingly, Benicardino et al. [44] reported that total mesophilic count increased by 2 CFU g−1
from packaging to the expiration date, although it is worth noting that the initial countswere 2 CFU g−1 higher in their studies than in the present one.
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a temperature increase of up to 8–10 °C for more prolonged periods has been reported [16].
Figure 1. Mesophilic aerobic, psychrophilic aerobic and mould and yeast counts in ready-to-eat sal-ads (RTESs) during storage in domestic refrigerator. Day 0 was the date of buying when RTESs arrived at the supermarket. Data are the mean ± SE. LSD value shows significant differences at p < 0.05.
3.2.2. Functional Quality of RTESs Ingredients during Storage Phenolic compounds are the major attributes responsible for antioxidant activity and
the functional properties of vegetable products [22–24], and thus, their content was eval-uated in each independent ingredient of the RTESs during storage. Corn salads had the highest total phenolic content, followed by radicchio, while the lowest levels were found in escarole, mainly in the white part of its leaves (Figure 2A). Similarly, a high total of phenolic content (90–110 mg 100 g−1) has been reported in other corn salad cultivars as compared with other vegetables used in RTESs, the major individual phenolic in corn sal-ads being chlorogenic acid, followed by diosmetin, rutin (quercetin 3-O-rutinoside), lute-olin, kaempferol 3-O-rutinoside and genistein, which were found at very low concentra-tions [47,48]. Phenolic content remained without significant changes in corn salads during the whole storage period, while significant increases (p < 0.05) occurred in radicchio, from 64.71 ± 3.87 mg 100 g−1 FW at day 0 to 95.89 ± 7.13 mg 100 g−1 FW at day 11 (Figure 2A). On the contrary, the total phenolic concentration decreased significantly (p < 0.05) in green parts of escarole leaves, from day 4 to day 8 (before the expiration date), while no signifi-cant changes occurred in white escarole leaves (Figure 2A).
Corn salads were the ingredient with the highest antioxidant activity with values of 175–200 mg 100 g−1 during storage, followed by radicchio, in which antioxidant activity at
Days in domestic refrigerator
0 4 7 11
log
CFU
g− 1
4
5
6
7
Mesophilic aerobic microflora Psychrophilic aerobic microfloraMoulds and yeast
LSD= 0.20
Figure 1. Mesophilic aerobic, psychrophilic aerobic and mould and yeast counts in ready-to-eatsalads (RTESs) during storage in domestic refrigerator. Day 0 was the date of buying when RTESsarrived at the supermarket. Data are the mean ± SE. LSD value shows significant differences atp < 0.05.
With respect to psychrophilic aerobic microflora, values remained unchanged (ca.6.2 log CFU g−1) from day 0 to day 7 of storage and increased by 1.0 log CFU g−1 atday 11 (Figure 1). Among psychrophilic microorganisms, Pseudomonas fluorescens has beenidentified as the main psychrophilic microorganism responsible for alterations in modifiedatmosphere-packaged salads [45,46] with values of 6.3 log CFU g−1 at the expirationdate, similar to counts for psychrophilic microorganisms found in the present experiment.However, in this previous study, mesophilic microorganisms were out of the safety limit
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and mould and yeast counts were higher than in the present study. The count increases forall these microorganisms in RTESs during storage in domestic refrigerators and could beaccelerated by temperature changes due to the continuous opening of the fridge since atemperature increase of up to 8–10 ◦C for more prolonged periods has been reported [16].
3.2.2. Functional Quality of RTESs Ingredients during Storage
Phenolic compounds are the major attributes responsible for antioxidant activityand the functional properties of vegetable products [22–24], and thus, their content wasevaluated in each independent ingredient of the RTESs during storage. Corn salads hadthe highest total phenolic content, followed by radicchio, while the lowest levels werefound in escarole, mainly in the white part of its leaves (Figure 2A). Similarly, a hightotal of phenolic content (90–110 mg 100 g−1) has been reported in other corn salad cul-tivars as compared with other vegetables used in RTESs, the major individual pheno-lic in corn salads being chlorogenic acid, followed by diosmetin, rutin (quercetin 3-O-rutinoside), luteolin, kaempferol 3-O-rutinoside and genistein, which were found at verylow concentrations [47,48]. Phenolic content remained without significant changes in cornsalads during the whole storage period, while significant increases (p < 0.05) occurred inradicchio, from 64.71 ± 3.87 mg 100 g−1 FW at day 0 to 95.89 ± 7.13 mg 100 g−1 FW atday 11 (Figure 2A). On the contrary, the total phenolic concentration decreased significantly(p < 0.05) in green parts of escarole leaves, from day 4 to day 8 (before the expiration date),while no significant changes occurred in white escarole leaves (Figure 2A).
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day 0 was 62.08 ± 3.71 mg 100 g−1 and increased significantly (p < 0.05) until day 7 (80.2 ± 4.77 mg 100 g−1) decreasing afterwards. Finally, escarole showed the lowest values of an-tioxidant activity, being significantly (p < 0.05) lower in white than in green portions of leaves and showing a decreasing trend during storage (Figure 2B). A high correlation was found between total phenolic content and antioxidant activity by taking into account data of all ingredients and sampling dates (y = 0.676x + 6.45; r2 = 0.849). Thus, in general, phe-nolic compounds could be considered as the major factor responsible for antioxidant properties and beneficial health effects of RTES consumption, as has been reported for a wide range of fresh vegetables [22–24,49], although in some RTESs, carotenoids and ascor-bic acid also make a high contribution to the antioxidant capacity of the produce [47]. However, it is worth noting that differences between corn salads and radicchio in total phenolic content were lower than differences in antioxidant activity, especially at the last sampling dates. These results could be explained by the higher ascorbic acid concentration reported in canon leaves [48,49] than in radicchio [45,50], which were 20–38 and 8–20 mg 100 g−1, depending on cultivars and growing conditions. Nowadays, it has been proved that the success of any technological food depends on consumer acceptance and that con-sumers demand high-quality products with added health properties [51,52]. Thus, since cannons are an ingredient with high phenolic content and antioxidant activity, it could be interesting to increase the relative proportion of corn salads in RTESs and provide infor-mation to consumers in package labels about this enhanced functional property.
Figure 2. Total phenolic content as mg gallic acid equivalent (A) and total antioxidant activity as mg L-ascorbic acid equivalent (B) in each one of the ingredients of ready-to-eat salads (RTESs) during storage in domestic refrigerator. Day 0 was the date of buying when RTESs arrived at the supermar-ket. Data are the mean ± SE. LSD value shows significant differences at p < 0.05.
3.2.3. Sensorial Quality of the Different RTES Ingredients Browning was detected at day 7 (a day after expiration date) in all the RTES ingredi-
ents, mainly in the white leaves of escarole and radicchio, 23.33 ± 5.53% and 15 ± 5%, re-spectively, which increased until the last sampling date, reaching values of 47 and 22%, respectively, while browning was very low (less than 3%) in corn salads and green esca-role leaves (Figure 3A). Accordingly, Mazzocco et al. [42] reported that browning started after seven days of storage in domestic refrigerators and was attributed to chlorophyll
A
Days in domestic refrigerator
0 4 7 11
Tota
l phe
nolic
con
tent
(mg
100
g− 1)
20
40
60
80
100
120Green escarole leaves White escarole leaves Corn saladsRadicchio
B
Days in domestic refrigerator
0 4 7 11
Tota
l ant
ioxi
dant
act
ivity
(mg
100
g− 1)
25
50
75
100
125
150
175
200
Green escarole leaves White escarole leaves Corn saladsRadicchio
LSD=4.05 LSD=6.57
Figure 2. Total phenolic content as mg gallic acid equivalent (A) and total antioxidant activity as mgL-ascorbic acid equivalent (B) in each one of the ingredients of ready-to-eat salads (RTESs) duringstorage in domestic refrigerator. Day 0 was the date of buying when RTESs arrived at the supermarket.Data are the mean ± SE. LSD value shows significant differences at p < 0.05.
Corn salads were the ingredient with the highest antioxidant activity with values of175–200 mg 100 g−1 during storage, followed by radicchio, in which antioxidant activityat day 0 was 62.08 ± 3.71 mg 100 g−1 and increased significantly (p < 0.05) until day 7(80.2 ± 4.77 mg 100 g−1) decreasing afterwards. Finally, escarole showed the lowest values
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of antioxidant activity, being significantly (p < 0.05) lower in white than in green portions ofleaves and showing a decreasing trend during storage (Figure 2B). A high correlation wasfound between total phenolic content and antioxidant activity by taking into account data ofall ingredients and sampling dates (y = 0.676x + 6.45; r2 = 0.849). Thus, in general, phenoliccompounds could be considered as the major factor responsible for antioxidant propertiesand beneficial health effects of RTES consumption, as has been reported for a wide range offresh vegetables [22–24,49], although in some RTESs, carotenoids and ascorbic acid alsomake a high contribution to the antioxidant capacity of the produce [47]. However, it isworth noting that differences between corn salads and radicchio in total phenolic contentwere lower than differences in antioxidant activity, especially at the last sampling dates.These results could be explained by the higher ascorbic acid concentration reported incanon leaves [48,49] than in radicchio [45,50], which were 20–38 and 8–20 mg 100 g−1,depending on cultivars and growing conditions. Nowadays, it has been proved that thesuccess of any technological food depends on consumer acceptance and that consumersdemand high-quality products with added health properties [51,52]. Thus, since cannonsare an ingredient with high phenolic content and antioxidant activity, it could be interestingto increase the relative proportion of corn salads in RTESs and provide information toconsumers in package labels about this enhanced functional property.
3.2.3. Sensorial Quality of the Different RTES Ingredients
Browning was detected at day 7 (a day after expiration date) in all the RTES ingre-dients, mainly in the white leaves of escarole and radicchio, 23.33 ± 5.53% and 15 ± 5%,respectively, which increased until the last sampling date, reaching values of 47 and 22%,respectively, while browning was very low (less than 3%) in corn salads and green esca-role leaves (Figure 3A). Accordingly, Mazzocco et al. [42] reported that browning startedafter seven days of storage in domestic refrigerators and was attributed to chlorophylldegradation and phenolic compound oxidation by polyphenol oxidase activity, which wasinduced by cutting vegetable products during processing operations. The percentage ofcut leaves showing visible dehydration symptoms increased during storage, reaching thehighest values in corn salads (≈60%) and the lowest in green escarole leaves (≈35%) atthe last sampling date (Figure 3B). Rotten areas started to be visible at day 7, affecting≈6% of the cut leaves of all ingredients and remained without significant changes untilthe last sampling date except for corn salads, in which this percentage increased up to≈10% (Figure 3C). Finally, general appearance decreased after day 4 in all ingredients ofRTESs, although all of them had scored higher than six at day 7 (8.33 ± 1.00, 7.56 ± 0.73,6.67 ± 1.41 and 6.67 ± 1.94 for green escarole, corn salads, radicchio and white escarole,respectively), still over the limit of acceptance for consumption (Figure 3D). Accordingly,Preti and Vinci [25] reported losses of general appearance in ready-to-eat salads after fourdays of storage.
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degradation and phenolic compound oxidation by polyphenol oxidase activity, which was induced by cutting vegetable products during processing operations. The percentage of cut leaves showing visible dehydration symptoms increased during storage, reaching the highest values in corn salads (≈60%) and the lowest in green escarole leaves (≈35%) at the last sampling date (Figure 3B). Rotten areas started to be visible at day 7, affecting ≈6% of the cut leaves of all ingredients and remained without significant changes until the last sampling date except for corn salads, in which this percentage increased up to ≈10% (Fig-ure 3C). Finally, general appearance decreased after day 4 in all ingredients of RTESs, although all of them had scored higher than six at day 7 (8.33 ± 1.00, 7.56 ± 0.73, 6.67 ± 1.41 and 6.67 ± 1.94 for green escarole, corn salads, radicchio and white escarole, respectively), still over the limit of acceptance for consumption (Figure 3D). Accordingly, Preti and Vinci [25] reported losses of general appearance in ready-to-eat salads after four days of storage.
Figure 3. Brown leaves (A), dehydrated leaves (B), leaves with rotten areas (C) and general appear-ance of ready-to-eat salads (RTESs) during storage in domestic refrigerator. (D) Day 0 was the date of buying when RTESs arrived at the supermarket. Data are the mean ± SE. LSD value shows sig-nificant differences at p < 0.05.
4. Conclusions This survey was performed with 296 participants, 55.7% female and 44.3% male, most
of them (75%) usual consumers once–twice a week of RTESs with mixed ingredients. The most important reason for not consuming RTESs was the use of plastic packages for envi-ronmental concerns. Consumers of RTESs gave more importance to the expiration date
A
Days in domestic refrigerator0 4 7 11
Brow
n le
aves
(%)
10
20
30
40
50
60
Green escarole leaves White escarole leaves Corn saladsRadicchio
B
Days in domestic refrigerator0 4 7 11
Deh
ydra
ted
leav
es (%
)
10
20
30
40
50
60
70Green escarole leaves White escarole leaves Corn saladsRadicchio
LSD= 2.79 LSD=3.27
C
Days in domestic refrigerator0 4 7 11
Leav
es w
ith ro
tten
area
s (%
)
2
4
6
8
10
Green escarole leaves White escarole leaves Corn saladsRadicchio
D
Days in domestic refrigerator0 4 7 11
Gen
eral
app
eara
nce
(0-1
0)
2
4
6
8
10
Green escarole leaves White escarole leaves Corn saladsRadicchio
LSD= 0.82 LSD=0.70
Figure 3. Brown leaves (A), dehydrated leaves (B), leaves with rotten areas (C) and general appear-ance of ready-to-eat salads (RTESs) during storage in domestic refrigerator. (D) Day 0 was the date ofbuying when RTESs arrived at the supermarket. Data are the mean ± SE. LSD value shows significantdifferences at p < 0.05.
4. Conclusions
This survey was performed with 296 participants, 55.7% female and 44.3% male,most of them (75%) usual consumers once–twice a week of RTESs with mixed ingredients.The most important reason for not consuming RTESs was the use of plastic packages forenvironmental concerns. Consumers of RTESs gave more importance to the expiration dateand visual quality properties when buying them than when consuming after storage in adomestic refrigerator at home. The microbiological quality of RTESs was maintained atacceptable and safe levels even after the expiration date. Finally, the content of bioactivecompounds, such as total phenolics and antioxidant activity, was generally maintained andeven increased during RTES storage in a domestic refrigerator, with the higher values beingfound in corn salads. Thus, quality properties of RTESs composed of mixed ingredientswere maintained in domestic refrigerators even after the expiration date, and these foodproducts could be considered healthy due to their high content of bioactive compounds,which would be enhanced by increasing the relative proportion of corn salads.
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Supplementary Materials: The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/su14063473/s1, Questionnaire is in Supplementary File.
Author Contributions: M.T.P. conceived and designed the work in association with other authors.J.M.L.-M. and J.M.V. performed the survey and the analytical determinations. M.T.P. and M.S.analysed the data and wrote the manuscript. All authors have read and agreed to the publishedversion of the manuscript.
Funding: This research did not receive any specific grant from funding agencies in the public,commercial, or not-for-profit sectors. University Miguel Hernández (UMH) has funded the laboratoryequipment and publishing fees.
Institutional Review Board Statement: This study was conducted according to the guidelines laiddown in the Declaration of Helsinki and all procedures involving research study participants wereapproved by the Ethics Committee of the University Miguel Hernández (reference DBA.MPP.01.21).
Informed Consent Statement: Informed consent was obtained from all participants involved inthe survey.
Data Availability Statement: Not applicable.
Acknowledgments: We are grateful to participants in the survey for answering the questionnaire, toUniversity Miguel Hernández for facilities and publishing fees and to Anthony Nicolson for editingand correcting the manuscript.
Conflicts of Interest: The authors declare no conflict of interest. The funders had no role in the designof the study; in the collection, analyses or interpretation of data; in the writing of the manuscript; orin the decision to publish the results.
References1. Rico, D.; Martin-Diana, A.B.; Barat, M.; Barry-Ryan, C. Extending and measuring the quality of fresh-cut fruit and vegetables: A
review. Trends Food Sci. Technol. 2007, 18, 373–386. [CrossRef]2. Bhalla, Y.; Gupta, V.K.; Jaitak, V. Anticancer activity of essential oils: A review. J. Sci. Food Agric. 2013, 93, 3643–3653. [CrossRef]
[PubMed]3. Sanchez-Bel, P.; Romojaro, A.; Egea, I.; Pretel, M.T. Wild edible plants as potential antioxidant or nutritional supplements for
beverages minimally processed. LWT-Food Sci. Technol. 2015, 62, 830–837. [CrossRef]4. De Corato, U. Improving the shelf-life and quality of fresh and minimally-processed fruits and vegetables for a modern food
industry: A comprehensive critical review from the traditional technologies into the most promising advancements. Crit. Rev.Food Sci. Nutr. 2020, 60, 940–975. [CrossRef]
5. Cook, R. The Dynamic U.S. Fresh Produce Industry: An Industry in Transition. Fresh Fruit and Vegetable Marketing and TradeInformation. 2008. Available online: http://are.ucdavis.edu/en/people/faculty/roberta-cook/articles-and-presentations/(accessed on 1 October 2021).
6. Gross, K.C.; Wang, C.Y.; Saltveit, M. The commercial storage of fruits, vegetables, and florist and nursery stocks. In AgriculturalResearch Service–Agriculture Handbook; Gross, K.C., Wang, C.Y., Saltveit, M., Eds.; United States Department of Agriculture:Washington, DC, USA, 2016; 780p. Available online: https://www.ars.usda.gov/arsuserfiles/oc/np/commercialstorage/commercialstorage.pdf (accessed on 20 September 2021).
7. Pilone, V.; Stasi, A.; Baselice, A. Quality preferences and pricing of fresh-cut salads in Italy: New evidence from market data. Br.Food J. 2017, 119, 1473–1486. [CrossRef]
8. Raffo, A.; Senatore, M.; Moneta, E.; Paoletti, F.; Peparaio, M.; Civitelli, E.S. Impact of different temperature abuse scenarios onsensory quality and off-odour formation in ready-to-eat salad leaves. Int. J. Food Sci. Technol. 2020, 56, 2345–2356. [CrossRef]
9. Arienzo, A.; Murgia, L.; Fraudentali, I.; Gallo, V.; Angelini, R.; Antonini, G. Microbiological quality of ready-to-eat leafy greensalads during shelf-life and home-refrigeration. Foods 2020, 9, 1421. [CrossRef] [PubMed]
10. Ramos, B.; Miller, F.A.; Brandão, T.R.; Teixeira, P.; Silva, C.L. Fresh fruits and vegetables-an overview on applied methodologiesto improve its quality and safety. Innov. Food Sci. Emerg. Technol. 2013, 20, 1–15. [CrossRef]
11. Sant’Anna, P.; Bernadette, D.G.; De Melo-Franco, B.; Maffeic, D. Microbiological safety of ready-to-eat minimally processedvegetables in Brazil: An overview. J. Sci. Food Agric. 2020, 100, 4664–4670. [CrossRef]
12. Ares, G.; Giménez, A.; Gámbaro, A. Sensory shelf life estimation of minimally processed lettuce considering two stages ofconsumers’ decision-making process. Appetite 2008, 50, 529–535. [CrossRef] [PubMed]
13. Wilson, M.D.; Stanley, R.A.; Eyles, A.; Ross, T. Innovative processes and technologies for modified atmosphere packaging of freshand fresh-cut fruits and vegetables. Crit. Rev. Food Sci. Nutr. 2019, 59, 411–422. [CrossRef]
14. Marinelli, L.; Maggi, O.; Aurigemma, C.; Tufi, D.; De, M.G. Fresh vegetables and ready-to eat salads: Phenotypic characterizationof moulds and molecular characterization of yeasts. Ann. Ig. Med. Prev. Comunita 2012, 24, 301–309.
Sustainability 2022, 14, 3473 12 of 13
15. Jeddi, M.Z.; Yunesian, M.; Gorji, M.E.H.; Noori, N.; Pourmand, M.R.; Khaniki, G.R.J. Microbial evaluation of fresh, minimally-processed vegetables and bagged sprouts from chain supermarkets. J. Health Popul. Nutr. 2014, 32, 391. [PubMed]
16. Tsironi, T.; Dermesonlouoglou, E.; Giannoglou, M.; Gogou, E.; Katsaros, G.; Taoukis, P. Shelf-life prediction models for ready-to-eatfresh cut salads: Testing in real cold chain. Int. J. Food Microbiol. 2017, 240, 131–140. [CrossRef] [PubMed]
17. Erickson, M.C.; Webb, C.C.; Diaz-Perez, J.C.; Phatak, S.C.; Silvoy, J.J.; Davey, L.; Payton, A.S.; Liao, J.; Ma, L.; Doyle, M.P. Surfaceand internalized Escherichia coli O157: H7 on field-grown spinach and lettuce treated with spray-contaminated irrigation water. J.Food Prot. 2010, 73, 1023–1029. [CrossRef] [PubMed]
18. Meyer, K.M.; Leveau, J.H.J. Microbiology of the phyllosphere: A playground for testing ecological concepts. Oecologia 2012, 168,621–629. [CrossRef]
19. FSANZ (Food Standards Australia New Zealand). Microbiological Quality Guide for Ready-to-Eat Foods. A Guide to Interpret-ing Microbiological Results. 2021. Available online: https://www.foodstandards.gov.au/code/microbiollimits/Documents/Guidelines%20for%20Micro%20exam.pdf (accessed on 24 June 2021).
20. FSAI (Food Safety Authority of Ireland). Guidance Note No. 3: Guidelines for the Interpretation of Results of Microbiological Testing ofReady-to-Eat Foods Placed on the Market (Revision 2); Food Safety Authority of Ireland (FSAI): Dublin, Ireland, 2016.
21. El-Ramady, H.R.; Domokos-Szabolcsy, E.; Abdalla, N.A.; Taha, H.S.; Fari, M. Postharvest management of fruits and vegetablesstorage. Sustain. Agric. Rev. 2015, 15, 65–152. [CrossRef]
22. Si, H.; Liu, D. Dietary antiaging phytochemicals and mechanisms associated with prolonged survival. J. Nutr. Biochem. 2014, 25,581–591. [CrossRef] [PubMed]
23. Luo, J.; Si, H.; Jia, Z.; Liu, D. Dietary anti-aging polyphenols and potential mechanisms. Antioxidants 2021, 10, 283. [CrossRef][PubMed]
24. Rolt, A.; Cox, L.S. Structural basis of the anti-ageing effects of polyphenolics: Mitigation of oxidative stress. BMC Chem. 2020,14, 50. [CrossRef] [PubMed]
25. Preti, R.; Vinci, G. Nutritional and sensory evaluation of ready-to-eat salads during shelf life. Agro Food Ind. Hi Tech 2016,27, 26–31.
26. Sanchez-Bel, P.; Egea, I.; Serrano, M.; Romojaro, A.; Pretel, M.T. Obtaining and storage of ready-to-use segments from traditionalorange obtained by enzymatic peeling. Food Sci. Technol. Int. 2012, 18, 63–72. [CrossRef] [PubMed]
27. Serrano, M.; Díaz-Mula, H.M.; Zapata, P.J.; Castillo, S.; Guillén, F.; Martínez-Romero, D.; Valverde, J.M.; Valero, D. Maturity stageat harvest determines the fruit quality and antioxidant potential after storage of sweet cherry cultivars. J. Agric. Food Chem. 2009,57, 3240–3246. [CrossRef] [PubMed]
28. Cano, A.; Hernández-Ruíz, J.; García-Cánovas, F.; Acosta, M.; Arnao, M.B. An end-point method for estimation of the totalantioxidant activity in plant material. Phytochem. Anal. 1998, 9, 196–202. [CrossRef]
29. Dinnella, C.; Torri, L.; Caporale, G.; Monteleone, E. An exploratory study of sensory attributes and consumer traits underlyingliking for and perceptions of freshness for ready to eat mixed salad leaves in Italy. Food Res. Int. 2014, 59, 108–116. [CrossRef]
30. Machín, L.; Giménez, A.; Vidal, L.; Ares, G. Influence of context on motives underlying food choice. J. Sens. Stud. 2014, 29,313–324. [CrossRef]
31. Langley, S.; Phan-Le, N.T.; Brennan, L.; Parker, L.; Jackson, M.; Francis, C.; Lockrey, S.; Verghese, K.; Alessi, N. The Good, the Bad,and the Ugly: Food Packaging and Consumers. Sustainability 2021, 13, 12409. [CrossRef]
32. Carrasco, R.; Labeaga, J.M.; Lopez-Salido, J.D. Consumption and habits. Evidence from panel data. Econ. J. 2005, 115, 144–165.[CrossRef]
33. Gardner, B.; de Bruijn, G.J.; Lally, P. A systematic review and meta-analysis of applications of the self-report habit index tonutrition and physical activity behaviours. Ann. Behav. Med. 2011, 42, 174–187. [CrossRef] [PubMed]
34. Jacobs, C.; Soulliere, K.; Sawyer-Beaulieu, S.; Sabzwari, A.; Tam, E. Challenges to the circular economy: Recovering wastes fromsimple versus complex products. Sustainability 2022, 14, 2576. [CrossRef]
35. Franz, R.; Welle, F. Recycling of post-consumer packaging materials into new food packaging applications—critical review of theeuropean approach and future perspectives. Sustainability 2022, 14, 824. [CrossRef]
36. Armitage, C.J.; Conner, M. Efficacy of the theory of planned behaviour: A meta-analytic review. Br. J. Soc. Psychol. 2001, 40,471–499. [CrossRef] [PubMed]
37. Stefan, V.; van Herpen, E.; Tudoran, A.A.; Lähteenmäki, L. Avoiding food waste by romanian consumers: The importance ofplanning and shopping routines. Food Qual. Prefer. 2013, 28, 375–381. [CrossRef]
38. Stancu, V.; Haugaard, P.; Lähteenmmäki, L. Determinants of consumer food waste behaviour: Two routes to food waste. Appetite2016, 96, 7–17. [CrossRef] [PubMed]
39. Gentil, E.C.; Gallo, D.; Christensen, T.H. Environmental evaluation of municipal waste prevention. Waste Manag. 2011, 31,2371–2379. [CrossRef]
40. Göbel, C.; Langen, N.; Blumentha, A.; Teitscheid, P.; Ritter, G. Cutting food waste through cooperation along the food supplychain. Sustainability 2015, 7, 1431–1438. [CrossRef]
41. Brennan, L.; Langley, S.; Verghese, K.; Lockrey, S.; Ryder, M.; Francis, C.; Phan-Le, N.T.; Hill, A. The role of packaging in fightingfood waste: A systematised review of consumer perceptions of packaging. J. Clean. Prod. 2021, 281, 125276. [CrossRef]
42. Widayat, W.; Praharjo, A.; Putri, V.P.; Andharini, S.N.; Masudin, I. Responsible consumer behavior: Driving factors of pro-environmental behavior toward post-consumption plastic packaging. Sustainability 2022, 14, 425. [CrossRef]
Sustainability 2022, 14, 3473 13 of 13
43. Manzocco, L.; Alongi, M.; Lagazio, C.; Sillani, S.; Nicoli, M.C. Effect of temperature in domestic refrigerators on fresh-cut Icebergsalad quality and waste. Food Res. Int. 2017, 102, 129–135. [CrossRef]
44. Miceli, A.; Gaglio, R.; Francesca, N.; Ciminata, A.; Moschetti, G.; Settanni, L. Evolution of shelf life parameters of ready-to-eatescarole (Cichorium endivia var. latifolium) subjected to different cutting operations. Sci. Hortic. 2019, 247, 175–183. [CrossRef]
45. Bencardino, D.; Vitali, L.A.; Petrelli, D. Microbiological evaluation of ready-to-eat iceberg lettuce during shelf-life and effectivenessof household washing methods. Ital. J. Food Saf. 2018, 7, 6913. [CrossRef] [PubMed]
46. Alfonzo, A.; Gaglio, R.; Miceli, A.; Francesca, N.; Di Gerlando, D.; Moschetti, G.; Settanni, L. Shelf life evaluation of fresh-cut redchicory subjected to different minimal processes. Food Microbiol. 2018, 73, 298–304. [CrossRef] [PubMed]
47. Calonico, C.; Delfino, V.; Pesavento, G.; Mundo, M.; Lo Nostro, A. Microbiological quality of ready-to-eat salads from processingplant to the consumers. J. Food. Nutr. Res. 2019, 7, 427–434. [CrossRef]
48. Ramos-Bueno, R.P.; Rincón-Cervera, M.A.; González-Fernández, M.J.; Guil-Guerrero, J.L. Phytochemical composition andantitumor activities of new salad greens: Rucola (Diplotaxis tenuifolia) and corn salad (Valerianella locusta). Plant Food Hum. Nutr.2016, 71, 197–203. [CrossRef] [PubMed]
49. Długosz-Grochowska, O.; Wojciechowska, R.; Kruczek, M.; Habela, A. Supplemental lighting with LEDs improves the biochemicalcomposition of two Valerianella locusta L. cultivars. Hortic. Environ. Biotechnol. 2017, 58, 441–449. [CrossRef]
50. Wojciechowska, R.; Dugosz-Grochowska, O.; Koton, A.; Zupnik, M. Effects of LED supplemental lighting on yield and somequality parameters of lamb’s lettuce grown in two winter cycles. Sci. Hortic. 2015, 187, 80–86. [CrossRef]
51. Nicoletto, C.; Pimpini, F. Influence of the forcing process on some qualitative aspects in radicchio “Rosso di Treviso Tardivo”(Cichorium intybus L., group rubifolium). Antioxidant capacity, phenols and ascorbic acid. Ital. J. Agron. 2010, 5, 43–52. [CrossRef]
52. Nassivera, F.; Sillani, S. Consumer perceptions and motivations in choice of minimally processed vegetables: A case study in Italy.Br. Food J. 2015, 117, 970–986. [CrossRef]