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Meat Science 77 (2007) 626–633

MEATSCIENCE

Ascorbate, green tea and grape seed extracts increasethe shelf life of low sulphite beef patties

Sancho Banon *, Pedro Dıaz, Mariano Rodrıguez, Marıa Dolores Garrido, Alejandra Price

Department of Food Technology and Science and Human Nutrition, Veterinary Faculty, University of Murcia, Espinardo, Murcia 30071, Spain

Received 31 July 2006; received in revised form 23 April 2007; accepted 21 May 2007

Abstract

Green tea (GTE) and grape seed (GSE) extracts are proposed as preservatives for increasing the shelf life of low sulphite raw beefpatties. The antioxidant and antimicrobial activities of both extracts were compared with ascorbate. Five groups were established forthe patties: Control (with no additives), S (100 SO2), SA (100 SO2 + 400 sodium ascorbate), ST (100 SO2 + 300 GTE) and SG (100SO2 + 300 GSE) (mg per kg of meat). Patties were stored at 4 �C in aerobic packaging for 0, 3, 6 or 9 days under retail display conditions.Meat spoilage (total viable and coliform counts, pH, lightness, chroma, hue angle, metmyoglobin and TBARS) was determined. Thesensory contribution of the extracts to cooked patties was evaluated (colour, odour, flavour and texture). The results pointed to the pos-sibility of using low SO2-vegetable extract combinations to preserve raw meat products. ST, SG and SA delayed microbial spoilage, red-ness loss and lipid oxidation, thus increasing the shelf life of the raw sulphite beef patties by 3 days. ST, SG and SA also delayed the onsetof rancid flavours in cooked patties. No anomalous sensory traits were caused by either extract. Ascorbate, GTE and GSE improved thepreservative effects of SO2 on beef patties, especially against meat oxidation. This suggested that the quantity of SO2 added can bereduced to obtain healthier raw meat products.� 2007 Elsevier Ltd. All rights reserved.

Keywords: Green tea; Grape seed; Vitamin C; Sulphite; Raw beef patties; Shelf life

1. Introduction

Consumers increasingly demand healthier meat prod-ucts, if possible free of chemical additives. The use of nat-ural preservatives to increase the shelf life of meat productsis a promising technology since many vegetal substanceshave antioxidant and antimicrobial properties. Grape(Vitis vinifera) and tea (Camellia sinensis) are of specialinterest due to their high content of phenolic compounds.Unlike skin, grape seed is rich in monomeric phenoliccompounds, such as catechin, epicatechin and epicate-chin-3-O-gallate, and in dimeric, trimeric and tetramericprocyanidins (Negro, Tomais, & Miceli, 2003). Green tealeaves are rich in epicatechin, epicatechin gallate, epigallo-catechin, teaflavin gallate, teaflavin monogallate A and B,

0309-1740/$ - see front matter � 2007 Elsevier Ltd. All rights reserved.

doi:10.1016/j.meatsci.2007.05.015

* Corresponding author. Tel.: +34 968 398265; fax: +34 968 364147.E-mail address: sanchoba@um.es (S. Banon).

and teaflavin digallate (Kuroda & Hara, 1999; Wanasund-ara & Shahidi, 1996).

The antioxidant activity of grape polyphenols orextracts has been verified in fish oil and frozen fish (Pazos,Gallardo, Torres, & Medina, 2004), cooked pork patties(Nissen, Byrne, Bertelsen, & Skibsted, 2004) and cookedturkey (Mielnik, Olsen, Vogt, Adeline, & Skrede, 2006)stored under retail display conditions. Green tea deriva-tives (at least 200 g/kg) have been added to increase theshelf life of raw, frozen and cooked meat patties (Gilet al., 2001; Jo, Son, Son, & Byun, 2003; McCarthy, Kerry,Kerry, Lynch, & Buckley, 2001a, McCarthy, Kerry, Kerry,Lynch, & Buckley, 2001b; Mitsumoto, O’Grady, Kerry, &Buckley, 2005; Tang, Kerry, Sheehan, Buckley, & Morris-sey, 2001). The derivatives showed effective antioxidantactivity, similar to that of such additives as BHA/BHT,although lower than that of rosemary extract (McCarthyet al., 2001b). Other studies have suggested that grape

S. Banon et al. / Meat Science 77 (2007) 626–633 627

extracts and green tea extracts may have an antibacterialeffect in vitro (An et al., 2004; Jayaprakasha, Selvi, & Saka-riah, 2003), although little information in this respect existsfor meat products.

It was thought that the addition of tea and grapeextracts might increase the shelf life of raw patties andother meat products stored under retail display condi-tions. Preliminary studies (Dıaz, Price, Rodrıguez, Garr-ido, & Banon, 2005) had shown that green tea andgrape seed extracts do not delay the colour deteriorationof raw beef patties, and that it is necessary to add sulph-ite. However, the use of sulphite in food has been ques-tioned due to its relation with certain health problems,including allergies, thiamine absorption deficit and disrup-tion of carbohydrate metabolism (Peroni & Poner, 1995).EU Directive 95/2/EC (1995) restricts the use of sulphitein burgers and other raw meat products (maximum450 mg SO2 per kg of meat). The FAO–WHO (1986)established a maximum permissible daily ingestion of0–0.7 mg SO2 per kg of body weight and considered itespecially important that SO2 be minimized in food withhigh thiamine content, such as red meat. The objectivewas to study the preservative properties of green teaand grape seed extracts for increasing the shelf life oflow sulphite beef patties. The antioxidant and antimicro-bial activities of both extracts were compared with that ofascorbate. The sensory contribution of both extracts tocooked patties was also studied.

2. Materials and methods

2.1. Sampling

Five groups (4 batches per group) of beef patties with adifferent formulation (mg per kg of meat) were established:Control (with no additives), S (100 SO2 as sodium metab-isulphite), SA (100 SO2 + 400 sodium ascorbate), ST (100SO2 + 300 watery green tea extract, GTE) and SG(100 mg SO2 + 300 mg water soluble grape seed extract,GSE). Meat and backfat were obtained from beef skirt(M. obliquus, trasversus and rectus abdominis). Twentygram salt per kilogram was added. The meat was minced(5 mm) using a P3298 cutter (Braher International, SanSebastian, Spain) and mixed for 5 min using a RM-60mixer (Mainca Granollers, Spain). The meat temperatureduring processing did not exceed 12 �C. Patties wereformed using a burger machine (100 g/patty) (Juan Marti-nez Perez Ltd., Murcia, Spain), to give average dimensionsof 10 cm diameter and 1.5 cm thickness. The patties werepackaged in a transparent polystyrene tray BA-85 (Sena,Sociedad de Envases Alimentarios, Aduna, Spain) andoverwrapped with an oxygen-permeable polypropylenefilm (6000–8000 cm3/m2 24 h at STP) (Raelma IndustriesMadrid Ltd., Spain). The patties were stored at 4 �C for0, 3 6 or 9 days in a display cabinet (Helkama, Finland)illuminated with white fluorescent light (620 lux), simulat-ing retail display conditions.

2.2. Extracts

Sodium metabisulphite and sodium ascorbate were pro-vided by Juan Martinez Perez Ltd., Murcia, Spain. Greentea extract (Ref. No. 285105) and seed grape extract(Ref. No. 255171) were provided by GMBH & Co. Kg,Vestenbergsgreuth, Germany. Green tea extract was awater soluble homogeneous powder, greenish to lightbrown in colour, with an astringent and slightly bitter taste.The total catechin and gallic acid content was greater than30% (dry weight basis). Grape seed extract was a water sol-uble homogeneous brown powder with a characteristictaste. The procyanidin (calculated as cyanidinchloride) ortannin (calculated as pyrogallol) content was 30–40%(dry weight basis). Microbiological counts for both extractswere: 103 maximum CFU total viable aerobic per g; maxi-mum 102 CFU enterobacter per g, maximum 102 CFUyeast and moulds per g; no Escherichia coli per g, no Pseu-

domonas aureginosa per g, no Salmonella per 25 g and noStaphylococcus aureus per g.

2.3. Raw meat analysis

Patty shelf life was determined by microbiological, sen-sory and physical–chemical meat spoilage indices. Analyseswere made on days 0, 3, 6 and 9 under retail display condi-tions. The microbiological and physical–chemical analyseswere made on raw samples. Five patties per five formula-tions and four control days were analyzed (N = 100). Thesamples used for microbiological analysis were blendedusing a masticator (IUL Instruments, GMBH, Konigswin-ter, Germany) and diluted in peptone water (Oxoid Ltd.CM0087, Basingstoke, Hampshire, United Kingdom).The total viable count (TVC) (CFU/g) was determined(ISO 4833:2003) using an Agar medium Plate Count (tryp-tone glucose yeast agar) (Oxoid Ltd. CM0325, Basing-stoke, Hampshire, United Kingdom). The total coliformcount (TCC) (CFU/g) was determined using a chromo-genic E. coli/coliform medium (Oxoid Ltd. CM956,Basingstoke, Hampshire, United Kingdom). For bothcounts, plates were incubated for 48 h at 37 �C in a ST6120 culture incubator (Heraeus S.A., Boadilla, Madrid,Spain).

Colour was measured using a CR-200/08 Chroma MeterII (Minolta Ltd., Milton Keynes, United Kingdom) mak-ing six measurements per patty. Results were expressed asCIELab values: Lightness (L*), Chroma (C*) and Hueangle (H*); C* = (a*2 + b*2)1/2. H* = tg�1 (b*/a*). The rela-tive metmyoglobin percentage (MM) was determinedaccording to Krzywicki (1978), using a U3200 spectropho-tometer (Hitachi, Tokyo, Japan). Thickness (4 cm diame-ter · 1.5 cm) samples were analysed. Six measurementswere made per sample. An integration sphere was used.A calcium sulphate tablet was used for calibration. Sam-ples were illuminated at 90� ± 10� angle. Light reflectionwas measured at 45� ± 5� angle. Samples were scannedfor 40 s using a 400–760 nm wavelength. The metmyoglo-

Table 1Reference food and/or substances used for sensory analysis of cooked beefpatties

Descriptors References

Colour

Meat Cooked beef fillet

Odour

Meaty Cooked beef filletLiver Cooked liverRancid Rancid seed oil

Flavour

Meaty Cooked beef filletLiver Cooked liverRancid Rancid seed oilAcid Citric acid 1 g l�1

Astringent Aluminium sulphate 0.02 g l�1

Texture

Juiciness 1 = Toast2 = Reheated cooked pork loin3 = Cooked ham4 = Turkey cold cuts5 = Carrots

Chewiness 1 = Fresh cheese2 = Frankfurt3 = Soft rye bread4 = Bread wheat5 = Freshly cooked pork loin

Fattiness Greasy beef patties

628 S. Banon et al. / Meat Science 77 (2007) 626–633

bin relative percentage was calculated as follows:% MM = [1.395 � (A572 � A730)/(A525 � A730)]100. Lipidoxidation was expressed as thiobarbituric acid reactivesubstances (TBARS) (mg malonaldehyde/kg sample), asdetermined by Botsoglou et al. (1994), using a UV2 spec-trophotometer (Pye Unicam Ltd., Cambridge, UnitedKingdom). The pH was measured using a micropH 2001pHmeter (Crison, Barcelona, Spain), and a combined elec-trode Cat. No. 52-22 (Ingold Electrodes, Inc., Wilmington,USA), to remove the possible contribution to microbiolog-ical or colour changes caused by to variations in the pH ofthe patties.

2.4. Cooked meat sensory analysis

A sensory analysis was made on the cooked patties.Before cooking, the patties were stored for 0, 3 and 6 daysunder retail display conditions, vacuum packed and frozen(�18 �C), for up to 30 days. The patties were thawed at4 �C and then cooked between two heating plates (Silanos,Liscia Average, Lavastoviglie Industriali, Italy) at 160 �Cfor 3 min. The patties reached an internal temperature of72 �C after 3 min, as measured by a portable T200 ther-mometer (Digitron Instrumentation Ltd., Merd Lane,Hertford, United Kingdom). The cooked samples wereimmediately covered with aluminium foil and kept at 60 �Cfor 5 min maximum in a sand bath (Braun, Esplugues deLlobregat, Spain) before being shown to the panellists. Rawpatties that had excessive microbiological counts accordingto EU Directive 94/65/EC (1994) were not analyzed.

The panelists were selected and trained according to ISO8586-1 (1992). The panel was formed by eight persons cho-sen from the university community. There were four train-ing sessions. In the two first sessions, the colour, odour,flavour and texture descriptors of cooked beef patties werestudied; the next two sessions were concerned with identify-ing, selecting and quantifying attributes to evaluate the pat-ties. A five-point scale was established, using other foods orsensory standards as reference (Table 1). Sensory analysiswas carried out according to ISO 4121 (2003). The descrip-tors used were: meat colour (MC); meaty (MO), liver (LO)and rancid (RO) odour; meaty (MF), liver (LF), rancid(RF), and acid (AF) flavour; juiciness (JU), chewiness(CH) and fattiness (FA). A linear scale of 1 (minimum)to 5 (maximum) was used: 1 = non-perceivable; 2 = per-ceivable; 3 = slight; 4 = moderate; 5 = strong. Each panel-list evaluated four beef patties from five differentformulations/storage days.

2.5. Statistics

The statistical model was designed completely at ran-dom. Extract addition was considered the main treatment.The effects of extract addition and storage time were ana-lysed by ANOVA (Scheffe means Test). The computer sta-tistics program used was Statistix 8.0 for Windows(Analytical Software, NY, USA).

3. Results and discussion

3.1. Microbial Spoilage

Table 2 shows the effects of extract addition and storagetime on total viable counts and total coliform counts in theraw beef patties. TVC and TCC increased significantly(P < 0.05) throughout storage, especially in Control andS (days 6 and 9). Unacceptable TVC (almost 6 CFU/g)were found in Control (day 6) and all groups (day 9). Sig-nificant differences (P < 0.05) in mean TVC and TCCbetween Control and SA, ST and SG were observed at days6 and 9. TVC and TCC were lower in SA, ST and SG thanin the Control (days 6 and 9). S presented intermediate val-ues, but S was not significantly different from SA, SG or STtreatments for TVC or TCC. The addition of 100 mg SO2/kg was not sufficient to delay the growth of total aerobicbacteria and total coliforms in raw beef patties, packagedin air and stored up to 9 days under retail display condi-tions. The SO2-extract combinations inhibited microbialgrowth, increasing shelf life by three days, although trendsindicated only marginal improvement in microbial qualityas a result of the addition of ascorbate, GTE and GSE.No pH changes that could have affected microbial growthwere found since the mean pH was similar in all the groupson all the days analysed.

The shelf life of raw meat is usually limited by microbialspoilage. Raw patties have a shelf life of around 7 days inrefrigeration and aerobiosis, depending on hygiene and pres-ervation conditions. (Mitsumoto et al., 2005; Montgomery,

Table 2Average total viable count (TVC) and total coliform count (TCC) (CFU/g) in raw beef patties stored in aerobic packaging for 0, 3, 6 and 9 days underretail display conditions

Day Control S SA SG ST

M ± SD M ± SD M ± SD M ± SD M ± SD

TVC 0 4.6 ± 0.23w 4.5 ± 0.36w 4.4 ± 0.30w 4.3 ± 0.42w 4.4 ± 0.33w

3 4.6 ± 0.23x 4.4 ± 0.42wx 4.3 ± 0.19w 4.6 ± 0.20x 4.3 ± 0.28w

6 5.6 ± 0.55ay 5.2 ± 0.82abx 4.4 ± 0.42bw 4.5 ± 0.30bx 4.3 ± 0.46bw

9 6.4 ± 0.58y 5.9 ± 0.86x 5.6 ± 0.81x 5.8 ± 1.35x 5.6 ± 0.77x

TCC 0 3.4 ± 0.56w 3.3 ± 0.60 3.2 ± 0.36 3.3 ± 0.50 3.4 ± 0.333 3.5 ± 0.33w 3.5 ± 0.43 3.2 ± 0.26 3.3 ± 0.36 3.2 ± 0.416 4.7 ± 0.66ax 3.5 ± 0.50b 3.2 ± 0.41b 3.2 ± 0.44b 3.2 ± 0.46b

9 5.5 ± 0.78ax 4.1 ± 0.80ab 3.7 ± 0.75b 3.8 ± 1.21b 3.4 ± 0.56b

S: sulphite; SA: sulphite + ascorbate; SG: sulphite + grape seed; ST: sulphite + green tea.Means with different superscripts are significantly different (P < 0.05).a, b, c, d: extract effects.w, x, y, z: storage day effects.

S. Banon et al. / Meat Science 77 (2007) 626–633 629

Parrish, Olson, Dickson, & Niebuhr, 2003; Sahoo & Anja-neyulu, 1997; Tang et al., 2005). SO2 is very active againstgram negative bacteria, such as Enterobacteriaceae (Banks,Dalton, Nychas, & Board, 1985). Reducing agents such asascorbate or polyphenols could protect SO2 against oxida-tion, enabling SO2 to act for more time. Some authors havesuggested that tea and grape polyphenols also have a certainantibacterial activity in vitro, although no specific studies onmeat products have been made. GSE would be mainly effec-tive against gram positive bacteria, with gallic acid as themain active component (Jayaprakasha et al., 2003). GTEwould inhibit E. coli, S. aureus, Staphylococcus epidermidis

and Streptococcus mutans (An et al., 2004). Currently useddoses of ascorbate do not have an antimicrobial effect onpsychrotrophics in raw patties (Sanchez-Escalante, Djen-ane, Torrescano, Beltran, & Roncales, 2001).

3.2. Meat oxidation

Table 3 shows the effects of extract addition and storagetime on CIELab colour and the relative percentage of met-myoglobin in raw beef patties. The CIELab colour coordi-nates presented considerable standard deviations, perhapsdue to the coarse mincing (5 mm grain). There was a grad-ual increase in H* and MM while C* values fell, colourchanges that are normally associated with the loss of red-ness in meat. L* was quite stable throughout storage inall patty groups, as has been reported by others (Bekhit,Geesink, Ilian, Morton, & Bickerstaffe, 2003; Dıaz et al.,2005; Jo et al., 2003; Mitsumoto et al., 2005). Extract addi-tion did not affect L*, differences in mean L* between treat-ments were not significant (P > 0.05). In contrast, Controland S patties showed a noticeable reduction in C* through-out storage compared with SA, SG and ST patties. Signif-icant differences (P < 0.05) in mean C* value betweenControl and ST–SG (days 3, 6 and 9), Control and SA(days 3 and 9), Control and S (day 3) and S and SA–SG–ST (day 9) were found. Mean C* was similar in SA,SG and ST on any storage day. The results for H* showed

the opposite behaviour. The greatest H* increases through-out storage were observed in Control and S. Significant dif-ferences (P < 0.05) in mean H* value between Control andSA–ST–SG (days 3, 6 and 9), Control and S (day 6), S andSA (days 3 and 9), S and SG–ST (day 9) were found. MeanH* was similar in SA, SG and ST on any storage day. MMvalues confirmed the results for the colour coordinates.MM gradually increased throughout storage in all thegroups. The greatest MM increases corresponded to Con-trol and S. Significant differences (P < 0.05) in mean MMvalue between Control and SA–ST–SG (days 3, 6 and 9),Control and S (days 3, 6 and 9), S and SA–ST–SG (days6 and 9), SA and SG–ST (day 9) were found. SA, ST andSG presented a noticeably lower MM values than Controland, to a lesser extent, S. No pH changes that could affectredness were found.

The addition of 100 SO2 mg/kg delayed colour deterio-ration and myoglobin oxidation in the raw beef pattiespackaged in air and stored up to 9 days under retail displayconditions. SO2 reduces the myoglobin haem group, whichfavours the formation of oxymyoglobin and deoxymyoglo-bin and reduces metmyoglobin, providing a fresh appear-ance to red meat (Wedzicha & Mountfort, 1991). Theaddition of low SO2-extracts, especially ascorbate, delayedeven further metmyoglobin formation and contributed toredness stabilization. According to An et al. (2004), rawbeef patties stored in aerobic packaging show a rapid col-our deterioration that cannot be stabilized by the sole addi-tion of ascorbate, GTE or GSE. However, these threeextracts combined with 100 mg SO2/kg stabilized rednessin raw beef patties to a similar extent as 300 mg SO2/kg.Other authors found different results. A high dose(1000 mg GTE/kg) of green tea ethanolic extract can delaythe loss of redness in raw pork patties throughout storage(Jo et al., 2003). 200–500 mg ascorbate/kg may have a cer-tain effect on redness in beef and buffalo patties (Ahn &Nam, 2004; Sahoo & Anjaneyulu, 1997; Sanchez-Escalanteet al., 2001; Tang et al., 2005) or not (Mitsumoto et al.,2005).

Table 3Average values and standard deviations of Lightness (L*), Chroma (C*), Hue angle (C*) and Metmyoglobin percentage (MM) in raw beef patties stored inaerobic packaging for 0, 3, 6 and 9 days under retail display conditions

Day Control S SA SG ST

M ± SD M ± SD M ± SD M ± SD M ± SD

L* 0 42.7 ± 6.75x 43.9 ± 3.74 43.9 ± 5.13 43.6 ± 7.60 43.3 ± 5.523 48.9 ± 6.60w 47.9 ± 5.69 45.8 ± 5.34 46.6 ± 5.59 45.4 ± 4.846 46.6 ± 4.50wx 46.2 ± 4.89 46.7 ± 5.83 47.8 ± 5.63 45.3 ± 5.669 47.2 ± 5.47wx 44.9 ± 5.30 45.5 ± 5.31 45.9 ± 6.02 47.4 ± 5.58

C* 0 17.3 ± 4.53w 20.2 ± 3.70w 20.1 ± 3.59w 20.5 ± 3.66wx 20.1 ± 2.97wx

3 14.8 ± 2.67awx 19.6 ± 3.20bw 20.3 ± 2.66bw 20.7 ± 3.58bw 21.2 ± 3.17bw

6 13.2 ± 4.37axy 15.1 ± 5.34abx 16.1 ± 4.12abx 17.4 ± 4.42bxy 17.6 ± 3.90bxy

9 10.6 ± 2.65ay 11.7 ± 2.05ay 15.8 ± 3.01bx 15.3 ± 4.20by 14.9 ± 3.72by

H* 0 22.8 ± 4.48x 22.2 ± 5.78x 21.1 ± 5.31 21.0 ± 5.42y 18.0 ± 5.41x

3 28.5 ± 6.37ax 23.0 ± 6.78abx 21.1 ± 7.21b 22.4 ± 6.68bxy 22.0 ± 5.79bx

6 40.0 ± 9.91aw 30.5 ± 11.2bwx 22.4 ± 4.89c 26.4 ± 5.79bcwx 24.3 ± 7.53cx

9 44.1 ± 10.9aw 37.8 ± 15.0abw 26.0 ± 7.67c 28.1 ± 7.63cw 30.6 ± 9.89cw

MM 0 6.7 ± 6.36z 5.1 ± 4.05y 2.5 ± 3.99 6.2 ± 3.32x 1.3 ± 3.08x

3 27.0 ± 5.74ay 6.8 ± 4.54by 8.0 ± 3.24b 4.9 ± 5.85bx 6.3 ± 2.63bx

6 43.2 ± 8.01ax 22.6 ± 17.2bx 8.3 ± 4.71c 7.1 ± 3.69cx 8.0 ± 5.27cx

9 72.2 ± 8.35aw 55.6 ± 14.5bw 10.6 ± 7.47d 24.3 ± 5.13cw 19.6 ± 13.9cw

S: sulphite; SA: sulphite + ascorbate; SG: sulphite + grape seed; ST: sulphite + green tea.Means with different superscripts are significantly different (P < 0.05).a, b, c, d: extract effects.w, x, y, z: storage day effects.

630 S. Banon et al. / Meat Science 77 (2007) 626–633

Table 4 shows the effects of extract addition and storagetime on TBARS in the raw beef patties. The TBARS valuesat day 0 indicated a noticeable degree of initial lipid oxida-tion in all patty groups. Raw patties can present high oxi-dation levels when meat and fat were not processed undervacuum. Mean TBARS at day 0 were higher in Controland S compared to SA, ST and SG, although no significant(P > 0.05) differences between groups were observed, dueto the high standard deviations obtained. On the contrary,significant differences (P < 0.05) in mean TBARS valuesbetween Control and SA–SG–ST (days 3, 6 and 9) andbetween Control and S (day 9) were found. SA, SG andST had similar mean TBARS values on any day of storage.TBARS increased strongly throughout storage in Controland S, but stabilized in SA, ST and SG. A final significant(P < 0.05) TBARS increase in S compared with Controlwas found on day 9.

Table 4Average values and standard deviations of thiobarbituric acid reagent substancdays under retail display conditions

Day Control S

M ± SD M ± SD

TBARS 0 0.83 ± 0.64z 0.78 ± 0.72x

3 2.47 ± 0.74ay 2.65 ± 0.97a

6 3.07 ± 0.71ax 2.96 ± 0.85a

9 3.86 ± 0.51aw 3.31 ± 0.86b

S: sulphite; SA: sulphite + ascorbate; SG: sulphite + grape seed; ST: sulphite +Means with different superscripts are significantly different (P < 0.05).a, b, c, d: extract effects.w, x, y, z: storage day effects.

SO2 can transform hydroperoxides into non-radicalforms and also act as a secondary lipid antioxidant (Gun-ther, Konig, Habicher, & Schwetlick, 1997). However, theaddition of 100 mg SO2/kg only delayed lipid oxidationwith respect to Control at day 9, corroborating preliminaryresults when 50, 100 and 300 mg SO2/kg were added (Diazet al., 2006). On the other hand, the low SO2-extract com-binations stabilized TBARS values for 9 days under retaildisplay conditions. The results for TBARS suggest thatthese combinations did not instantaneously reduce lipidoxidation on addition, but were effective antioxidantsthroughout patty storage. The antioxidant effect on meatlipids of ascorbate, tea and grape polyphenols has beenreported by several authors (Bozkurt, 2006; Gil et al.,2001; Jo et al., 2003; Mielnik et al., 2005; Mitsumotoet al., 2005; Tang et al., 2001; Tang et al., 2005; Nissenet al., 2004). Ascorbate can reduce haematic Fe3+, react

es (TBARS) in raw beef patties stored in aerobic packaging for 0, 3, 6 and 9

SA SG ST

M ± SD M ± SD M ± SD

0.44 ± 0.39 0.51 ± 0.47 0.45 ± 0.40w 0.60 ± 0.55b 0.84 ± 0.69b 0.47 ± 0.37b

w 0.78 ± 0.81b 0.63 ± 0.46b 0.45 ± 0.34b

w 0.69 ± 0.33c 0.60 ± 0.33c 0.47 ± 0.40c

green tea.

Table 5Mean values and standard deviations of sensory scores in cooked beef patties previously stored in aerobic packaging for 0, 3 and 6 days under retaildisplay conditions

Day C S SA SG ST

M ± SD M ± SD M ± SD M ± SD M ± SD

MC 0 4.2 ± 0.5 4.1 ± 0.8 4.1 ± 0.7 4.0 ± 0.8 4.0 ± 0.63 4.2 ± 0.8 4.0 ± 0.9 3.9 ± 0.7 3.8 ± 0.8 3.8 ± 0.76 3.8 ± 1.0 3.7 ± 0.6 3.5 ± 0.8 3.9 ± 0.6

MO 0 4.0 ± 0.5 3.6 ± 0.7 3.9 ± 0.7 3.8 ± 0.7x 3.5 ± 0.73 3.9 ± 1.1 3.5 ± 1.1 3.8 ± 1.0 3.4 ± 0.9wx 3.8 ± 0.66 2.9 ± 0.8 3.3 ± 0.7 2.8 ± 0.9w 3.1 ± 0.7

LO 0 1.8 ± 0.5 1.9 ± 0.7 2.1 ± 0.6 2.2 ± 0.4 1.9 ± 0.53 1.9 ± 0.7 1.8 ± 0.4 1.9 ± 0.6 1.8 ± 0.4 1.9 ± 0.56 1.4 ± 0.4 1.6 ± 0.5 1.6 ± 0.4 1.7 ± 0.7

RO 0 1.4 ± 0.4x 1.2 ± 0.4x 1.5 ± 0.5wx 1.1 ± 0.2x 1.3 ± 0.4x

3 2.2 ± 1.0w 2.2 ± 0.8w 1.2 ± 0.2x 1.3 ± 0.5x 1.4 ± 0.5wx

6 2.7 ± 0.9w 1.9 ± 0.6w 2.4 ± 0.7w 2.1 ± 0.8w

MF 0 4.1 ± 0.8 3.7 ± 0.7 3.9 ± 0.8 3.8 ± 1.0 3.5 ± 0.83 3.7 ± 1.2 3.2 ± 1.1 3.9 ± 0.7 3.6 ± 0.9 3.7 ± 0.76 2.8 ± 1.1 3.2 ± 0.5 3.1 ± 0.7 3.3 ± 0.7

LF 0 2.1 ± 0.7 1.8 ± 0.6 2.4 ± 0.9 2.7 ± 0.7w 2.4 ± 0.63 2.1 ± 0.7 1.8 ± 0.8 2.2 ± 0.6 1.7 ± 0.5x 1.8 ± 0.96 1.8 ± 0.7 2.0 ± 0.5 1.5 ± 0.6x 2.0 ± 0.4

RF 0 1.2 ± 0.4x 1.3 ± 0.4x 1.2 ± 0.3x 1.1 ± 0.2x 1.4 ± 0.63 2.5 ± 1.2aw 2.6 ± 0.9aw 1.3 ± 0.4bx 1.2 ± 0.2bx 1.7 ± 0.9b

6 3.1 ± 0.6aw 1.9 ± 0.7bw 2.2 ± 0.4bw 2.2 ± 0.7b

AF 0 1.4 ± 0.7 1.4 ± 0.5 1.4 ± 0.3 1.4 ± 0.4x 1.4 ± 0.5x

3 1.1 ± 0.4 1.4 ± 0.6 1.4 ± 0.4 1.2 ± 0.5x 1.3 ± 0.4x

6 2.2 ± 0.7 1.7 ± 0.8 2.2 ± 1.0w 2.2 ± 0.9w

JU 0 3.7 ± 0.5 3.9 ± 0.6 3.1 ± 0.3 4.0 ± 0.5 3.4 ± 0.63 3.6 ± 0.5 3.6 ± 0.4 3.4 ± 0.5 3.7 ± 0.4 3.4 ± 0.66 3.3 ± 0.5 3.4 ± 0.4 3.8 ± 0.4 3.1 ± 0.3

CH 0 3.9 ± 0.2 3.7 ± 0.5 3.9 ± 0.2 3.6 ± 0.4 3.6 ± 0.43 4.1 ± 0.5 3.7 ± 0.4 3.6 ± 0.6 3.6 ± 0.3 3.7 ± 0.46 3.7 ± 0.5 3.7 ± 0.5 3.4 ± 0.4 3.7 ± 0.4

FA 0 2.6 ± 0.5 2.6 ± 0.5 2.7 ± 0.6 2.7 ± 0.5 2.6 ± 0.63 2.6 ± 0.5 2.6 ± 0.5 2.7 ± 0.8 2.7 ± 0.5 2.6 ± 0.66 2.6 ± 0.4 2.5 ± 0.6 2.6 ± 0.5 2.7 ± 0.4

Meat colour (MC); meaty (MO), liver (LO) and rancid (RO) odour; meaty (MF), liver (LF), rancid (RF) and acid flavour (AF); juiciness (JU), chewiness(CH) and fattiness (FA).S: sulphite; SA: sulphite + ascorbate; SG: sulphite + grape seed; ST: sulphite + green tea.Means with different superscripts are significantly different (P < 0.05).a, b, c, d: extract effects.w, x, y, z: storage day effects.

S. Banon et al. / Meat Science 77 (2007) 626–633 631

with O2 and inhibit free radical formation, but may alsoform the prooxidative species, Fe2+ and Cu+ (Buettner &Jurkiewicz, 1996). According to Yin, Faustman, Riesen,and Williams (1993), small vitamin C concentrations delaymetmyoglobin formation in vitro, whereas high vitamin Cconcentrations increase lipid and oxymyoglobin oxidation.Mielche and Bertelsen (1994) found the opposite results.Polyphenolic extracts are excellent electron and protondonors, and their intermediate radicals are quite stabledue to electron delocalization phenomena and due to thelack of positions attackable by O2 (Djenane, Montanes,& Roncales, 2005). Tea polyphenols are metal chelatingagents and also act on free radicals, since their benzene

rings, inhibiti chain reactions during lipid oxidation (Tang,Kerry, Sheehan, & Buckley, 2002).

3.3. Sensory quality

Table 5 shows the effects of extract addition and storagetime on the sensory attributes of cooked beef patties. Thecooked patties had a lower MC, MO and MF values thanthe cooked beef fillet used as reference, probably due tosensory changes resulting from mincing, mixing and aero-bic packaging, among other reasons. In general, minorlosses of colour, odour, flavour and texture were observedduring storage. Slight but significant (P < 0.05) RO and

632 S. Banon et al. / Meat Science 77 (2007) 626–633

RF increases were only observed in all patty groups duringstorage. The addition of S, SA, ST and SG did not produceappreciable odour, flavour or texture changes in cookedpatties. The only significant (P < 0.05) differences in meanRF values were between Control and SA–ST–SG (day 3),and between S and SA–ST–SG (days 3 and 6). A slightRF was detected in Control and S after day 3. 100 gSO2/kg did not prevent rancidity in beef patties, packagedin air, stored up to 6 days under retail display conditionsand later cooked. However, the low SO2-extract combina-tions delayed rancidity, in agreement with the TBARSresults in raw patties. Patties without added ascorbate,GTE or GSE showed TBARS levels higher than 2.3MDA/kg, the TBARS threshold value above which beefrancidity is detected by sensory analysis (Campo et al.,2006). Jo et al. (2003) found that GTE improved colourand did not affect the odour, flavour or tenderness ofcooked pork patties. Mitsumoto et al. (2005) found thattea catechins caused a certain grey discolouration incooked beef and chicken patties, but no such discolour-ation was observed in this study. Neither vegetable extractcontributed astringent flavour to cooked beef patties.

4. Conclusions

The results pointed to the potential value of using lowSO2-vegetable extract combinations to preserve raw meatproduct. These combinations acted on the major causesof raw meat deterioration: microbial spoilage, redness lossand lipid oxidation. Ascorbate, GTE and GSE improvedthe preservative effects of low SO2 doses and had good sen-sory properties. This offers the possibility of reducing SO2

levels in meat products, in accordance with FAO–WHOrecommendations. Similarly, Roller et al. (2002) demon-strated that chitosan (polymeric b-1-4-N-acetylglucos-amine) allows the amount of SO2 used to preserve rawpork sausage to be reduced from 340 to 170 mg/kg. Ascor-bate, GTE and GSE seem to play a similar preservativerole in raw meat products, although ascorbate was addedto patties at a higher dose. The results suggest that it isunlikely that either extract can replace ascorbate or similaradditives in industrial formulations of raw meat products.Tea and grape would probably be more effective preserva-tives in precooked or cooked meat products (Gil et al.,2001; Jo et al., 2003; Mielnik et al., 2005; Mitsumotoet al., 2005; Nissen et al., 2004), a question that merits fur-ther study.

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