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Food Control 34 (2013) 675e680

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Food Control

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Potential use of Lactobacillus casei AST18 as a bioprotective culturein yogurt

Hongjuan Li, Lu Liu, Shuwen Zhang, Hankie Uluko, Wenming Cui, Jiaping Lv*

Key Laboratory of Agro-Products Processing, Ministry of Agriculture, Institute of Agro-Products Processing Science and Technology,Chinese Academy of Agricultural Science, PR China

a r t i c l e i n f o

Article history:Received 3 February 2013Received in revised form10 June 2013Accepted 15 June 2013

Keywords:YogurtAntifungalLactobacillus caseiBioprotective culture

* Corresponding author. Institute of Agro- ProduTechnology, Chinese Academy of Agricultural ScienceRoad, Haidian District, P.O.Box 5109, Beijing 10019362815542; fax: þ86 (0)10 62810295.

E-mail address: lvjp586@gmail.com (J. Lv).

0956-7135/$ e see front matter � 2013 Elsevier Ltd.http://dx.doi.org/10.1016/j.foodcont.2013.06.023

a b s t r a c t

This study investigated the inhibitory effects of Lactobacillus casei AST18 as a biocontrol agent on fungispoilage in yogurt. In a yogurt preservation period experiment and mould-proof accelerated testing at4 �C, the addition of 2% (v/v) L. casei AST18 in yogurt completely inhibited mould growth; mould growthwas significantly delayed and spore germination was inhibited at 30 �C. The addition of L. casei AST18improved the quantity of Lactobacillus, but the number of Streptococcus lactis in 2% AST18-added yogurtdecreased by 1.0 Log (cfu/mL) compared with that in the blank group. L. casei AST18 exerted no signif-icant influence on viscosity, water holding capacity, sensory quality, pH and titratable acidity. The post-acidification effect of L. casei AST18 was low. L. casei AST18 conspicuously inhibited the growth of fila-mentous fungi. Therefore, L. casei AST18 can be used as a bioprotective culture in yogurt to prevent fungalgrowth and extend shelf life.

� 2013 Elsevier Ltd. All rights reserved.

1. Introduction

Lactic acid bacteria (LAB) have long been used in food productsand feeds. LAB are used and studied for their capacity to inhibitunwanted bacteria and increase the shelf life of products (Schnurer& Magnusson, 2005). These bacteria can decrease pH and produceantibacterial compounds. Over the last few years, many researchershave found that LAB strains can inhibit mould and yeast growth(Belal Jamal & Zaiton, 2011; Brosnan, Coffey, Arendt, & Furey, 2012;Lowe & Arendt, 2004; Ryan, Dal Bello, & Arendt, 2008;Wuhjideligen, Sudun, & Miyamoto, 2011). Li et al. (2011) isolatedstrain AST18 with antifungal activity from Chinese traditional dairyproducts and identified it as Lactobacillus casei. The antifungal ac-tivities of L. casei AST18 exerted a synergistic effect caused by lacticacid and cyclo-(Leu-Pro) (Li, Liu, Zhang, Cui, & Lv, 2012). The puri-fication of antifungal n compounds from LAB is complicated, andisolated antifungal compounds remain a controversial subject.

LAB is a generally recognized as safe (GRAS) microorganism andbelongs to the qualified presumption of safety list in Europe(Bernardeau, Vernoux, Henri-Dubernet, & Gueguen, 2008). It can be

cts Processing Science ands No.2 Yuan Ming Yuan West, PR China. Tel.: þ86 (0)10

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used as a protective culture in food. Ryan et al. (2008) reported thatwhen 20% of Lactobacillus plantarum sourdoughs were incorpo-rated into wheat bread formulations, the resultant bread productsshowed increased shelf life and resistance against common breadspoilage organisms. Lavermicocca et al. (2000) reported thatL. plantarum culture filtrate grown on whole wheat flour hydroly-sate almost completely inhibited the growth of Penicillium roque-forti in vitro.

Yogurt has gained special prominence and economic impor-tance because of its high nutritional value and health benefits.Yogurt consumption has steadily increased over the last 30 years(Penna, Gurram, & Barbosa-Canovas, 2006). Fungus is an acid-tolerant microorganism. Fungal contamination can easily occur atall stages of food processing from raw materials to finished prod-ucts because fermented milks and yogurt are generally consideredmicrobiologically stable (Delavenne et al., 2013). Filtenborg,Frisvad, and Thrane (1996) indicated that, the most importantspoilage species of yogurt and cheese are: Penicillium commune andPenicillium nalgiovense. Debaryomyces hansenii, Kluyveromycesmarxianus, Rhodotorula mucilaginosa, Yarrowia lipolytica, Zygo-saccharomyces bailii and Penicillium brevicompactum are also themost frequently encountered fungal contaminants in yogurt andfermented milks (Mayoral et al., 2005). Few studies have beendevoted to the application of LAB as bioprotective culture in yogurtand other dairy products. Delavenne et al. (2013) were the first toreport the antifungal activity of Lactobacillus harbinensis, which

Fig. 1. pH values of different inoculums during storage at 4 �C.

H. Li et al. / Food Control 34 (2013) 675e680676

showed a very strong antifungal effect in yogurt (compared withthe control) by completely inhibiting all tested fungi. Liu and Tsao(2009) investigated the antagonistic dairy yeast D. hansenii,which inhibited the growth of the following dairy moulds: Asper-gillus sp., Byssochlamys fulva, Byssochlamys nivea, Cladosporium sp.,Eurotium chevalieri, Penicillium candidum and P. roqueforti. Thestrain exhibited good inhibitory effects on fungi in cheese andyogurt.

In the present study, we describe the antifungal activities ofL. casei AST18 as a finished bioprotective culture in yogurt. Thephysical and microbiological characteristics of the AST18- addedyogurt were also determined. To the best of our knowledge, thisstudy is the first systematic research on the application of anti-fungal L. casei in yogurt.

2. Materials and methods

2.1. L. casei AST18 and indicator fungi

L. casei AST18 (Accession Number: HM773423) was cultured ondeMan Rogosa and Sharpe (MRS) agar or in MRS broth (Land BridgeTechnology Co., China) at 37 �C for 24 h and maintained for longstorage at �80 �C in MRS supplemented with 25% (v/v) glycerol.Penicillium sp. isolated from spoiled cheese was used as the indi-cator fungi. It was maintained on potato dextrose agar (Land BridgeTechnology Co., China) at 30 �C for 4 days and stored at 4 �C.

2.2. Preparation of yogurt

Milk was sterilised at 110 �C for 5 min and cooled to 42e45 �C.The starter (Chr.Hansen YF-L822) was added, according to themanufacturer’s instructions [0.08% (m/v)]. The adjunct cultureL. casei AST18 was added to the milk at 0, 2, 4, 6 and 8% (v/v).Fermentation was conducted at 42 �C for 5 h. Both the control andL. casei AST18-added yogurt samples were stored at 4 �C, for 16 hafter ripening.

2.3. Analyses of the physical and chemical properties of yogurtduring storage at 4 �C

The pH values of the yogurt samples weremeasured at 17e20 �Cusing a pH meter (HANNA, pH211, Italy) after calibrating with freshpH 4.0 and 7.0 standard buffers. Titratable acidity (TA) was

Table 1Standard of organoleptic evaluation grading of yogurt.

Character Scorerange

Colour(10 scores)

Milky white (slightly yellowish), uniform colour 10e8Pale yellow 8e6Sallow/greyish white 6e4Black or green mildew, anomalous colours 4e0

Flavour(40 scores)

Yogurt inherent taste, sweet and sour 40e35Overly acidic or overly sweet 35e20Astringency 20e10Bitterness 10e5Abnormal taste 5e0

Texture(50 scores)

Organization delicate, clot uniform, no bubbles,no whey precipitation

50e40

Organization delicate, clot uneven size, no bubbles,whey precipitation

40e30

Organization rough, inhomogeneity, No bubbles,whey precipitation

30e20

Organization rough, inhomogeneity, bubbles,whey precipitation

20e10

Organization rough, inhomogeneity, largenumber of bubbles, Grainy

10e0

determined aftermixing a yogurt samplewith 10mL of hot distilledwater and titrating with 0.1 N NaOH using 0.5% phenolphthaleinindicator (Dave & Shah, 1997).

Water holding capacity (WHC) was also determined. The weightof an empty centrifuge tube was recorded, and 15 mL yogurt waspoured into it, after which the entire weight was recorded. Theyogurt was centrifuged (Anting, LXJ-IIB, Shanghai, China) at5000 rpm for 20 min, and the supernatant was drained. Thecentrifuge tube was inverted for 10 min and weight was measured.

WHC (%) was expressed as:

WW0

� 100

WHC (%) where W is the weight of the precipitate and W0 is theweight of the yogurt.

Apparent viscosity was determined using an Ubbelohdeviscometer (Brookfield, USA) on 50 mL yogurt samples at 25 �C.Samples were stirred for 50 s before measurement. Readings wereconverted to centipoise units. All viscosity values weremeasured at50 � g with spindle #64 (Ozturk & Oner, 1999).

2.4. Sensory analysis

The evaluation was made in accordance with ‘Chinese dairyindustry normsd yogurt sensory quality evaluation rules’. Table 1shows the details of the evaluation. A trained panel of 15 asses-sors evaluated the samples in terms of texture, colour, flavours andtaste. A 100-point scale was used to evaluate the sensory percep-tion of the yogurt samples.

The aforementioned experiments were performed in triplicate.

Table 2Titratable acidity of different inoculums of AST18-added yogurt during storage at4 �C.

Inoculation TA (�T)

1D 7D 14D 21D

2% 60.0 � 3.6a 60.7 � 0.6c 64.0 � 3.5a 69.0 � 6.3a

4% 59.3 � 0.6a 67.0 � 1.7a 66.7 � 1.2a 65.7 � 2.5a

6% 60.3 � 4.0a 62.3 � 2.5bc 67.3 � 1.2a 69.7 � 1.5a

8% 60.0 � 0.0a 65.0 � 0.0ab 64.0 � 1.0a 63.3 � 1.5a

Blank 59.7 � 1.5a 63.0 � 1.7abc 63.3 � 3.1a 67.7 � 7.0a

Number of samples n ¼ 3.Values in the same column with different superscript letters are significantlydifferent (P < 0.05).

Table 3Apparent viscosity of different inoculums of AST18-added yogurt during storage at4 �C.

Inoculum Viscosity (Cp)

1D 7D 14D 21D

2% 356 � 13.8a 384 � 31.8a 304 � 6.9b 276 � 24.0a

4% 356 � 12.0a 352 � 13.9a 340 � 13.9a 316 � 30.2a

6% 336 � 12.0a 324 � 0.0a 304 � 6.9b 296 � 13.9a

8% 352 � 13.8a 368 � 13.9a 356 � 6.9a 318 � 21.6a

Blank 352 � 13.8a 364 � 36.7a 312 � 0.0b 304 � 6.4a

Number of samples n ¼ 3.Values in the same column with different superscript letters are significantlydifferent (P < 0.05).

Fig. 2. Sensory evaluation with different inoculums of AST18-added yogurt.

H. Li et al. / Food Control 34 (2013) 675e680 677

2.5. Microbiological analyses

Samples for counts of Streptococcus thermophilus and Lactoba-cillus were spread plated on M17 and MRS agar (Land BridgeTechnology Co., China), respectively. The M17 agar culture wasincubated for 24 h at 42 �C and the MRS agar culture was anaero-bically incubated for 5 days at 37 �C. Microbiological count datawere expressed as a log of colony-forming units per millilitre ofyogurt (Salvador & Fiszman, 2004).

2.6. Challenge tests on yogurt

2.6.1. Experiment on yogurt preservation periodThe yogurt was placed in a Petri dish and stored at 4 �C and

30 �C, and then the fungal contamination level was determined.

2.6.2. Mould-proof accelerated testingA total of 20mLyogurt was added to the sterilised Petri dish, and

then the spore of Penicillium sp. was inoculated with an inoculatingloop (60e80 spores per container). The yogurt was placed in a Petridish and stored at 4 and 30 �C, after which the fungal contamina-tion level was determined.

The aforementioned experiments were performed in triplicate.

3. Results

3.1. Assessment of the physical and chemical properties of yogurtduring storage at 4 �C

3.1.1. pHFig. 1 illustrates the changes in yogurt pH, which decreased to

almost the same extent for all the different incubation startercultures and the blank group. During the 21 storage periods, thepH of an entire sample was greater than 4.0, indicating thatL. casei AST18 has weak post-acidification capability. The pH of 2%

Table 4Water holding capacity of different inoculums of AST18-added yogurt during storageat 4 �C.

Inoculum The water holding capacity (%)

1D 7D 14D 21D

2% 0.20 � 0.00a 0.19 � 0.01b 0.18 � 0.01b 0.16 � 0.01a

4% 0.21 � 0.01ab 0.20 � 0.01a 0.18 � 0.01b 0.18 � 0.00a

6% 0.19 � 0.00b 0.21 � 0.01a 0.18 � 0.00b 0.17 � 0.01a

8% 0.21 � 0.00c 0.21 � 0.00a 0.19 � 0.00ab 0.18 � 0.00a

Blank 0.21 � 0.01ab 0.20 � 0.01a 0.21 � 0.01a 0.16 � 0.01a

Number of samples n ¼ 3.Values in the same column with different superscript letters are significantlydifferent (P < 0.05).

AST18-added sample was 0.14 units higher than that of the blankgroup.

3.1.2. TATable 2 shows the changes in TA which minimally increased

during an entire storage period. No significant difference wasobserved in all the five treatments at initial and end stages ofstorage period. At the end of storage, the TA of 8% AST18-addedyogurt was lower than that of 2% AST18-added yogurt, indicatingthat L. casei AST18 may have inhibited the acidogenicity of thecommercial yogurt starter.

3.1.3. Apparent viscosityTable 3 shows the changes in apparent viscosity. During a

storage period, viscosity gradually decreased with time. The dif-ference between the four AST18-added yogurt samples and theblank group was non-significant (P > 0.05).

3.1.4. Water holding capacityTable 4 shows the changes in WHC during the storage periods,

the WHC gradually decreased with time. The difference between

Fig. 3. Counts of Lactobacillus in different inoculums of AST18-added yogurt duringstorage at 4 �C.

Fig. 4. Counts of S. thermophilus in different inoculums of AST18-added yogurt duringstorage at 4 �C.

Table 5Shelf life saving experiment on different inoculums of AST18-added yogurt at 4 �C.

Inoculation Time (day)

2 6 10 14 18 22

2% 0 0 0 0 0 04% 0 0 0 0 0 06% 0 0 0 0 0 08% 0 0 0 0 0 0Blank 0 0 0 1 2 2

The digits stand for the numbers of samples with fungal growth (each inoculum hadthree parallel samples).

H. Li et al. / Food Control 34 (2013) 675e680678

the four AST18-added yogurt samples and the blank group wasnon- significant (P > 0.05).

3.2. Sensory analysis

Sensory analysis was performed using the data in Table 1. Theresults are shown in Fig. 2. The difference between the four AST18-added yogurt samples and the blank group was non-significant(P > 0.05).

3.3. Microbiological analyses

3.3.1. Counts of Lactobacillus during storage at 4 �CThe changes in the viable counts of Lactobacillus during yogurt

storage are shown in Fig. 3. No Lactobacillus was detected in theblank group. As shown in the figure, the counts of Lactobacillusduring storage minimally decreased. The initial count of 2% AST18-added yogurt was 7.70 Log (cfu/mL), and that of 8% AST18-added

Fig. 5. Shelf life saving experiment of 2% AST18-added yogurt and blank samples at4 �C.

yogurt was 8.25 Log (cfu/mL). These results indicate that L. caseiAST18 can improve the viable count of yogurt bacteria.

3.3.2. Counts of S. thermophilus during storage at 4 �CFig. 4 shows that the counts of S. thermophilus during storage

decreased at the initial stage, and then slightly increased. Thisresult may be attributed to the decrease in Lactobacillus whichexerted a competitive inhibition effect on S. thermophilus growth.At the end of the storage period, the blank group had the highestcounts of S. thermophilus, indicating that the addition of L. caseiAST18 inhibits the growth of S. thermophilus. Slight differenceswere observed between the different incubation groups.

3.4. Challenge tests on yogurts

3.4.1. Experiment on the preservation period of yogurtThe yogurt was placed in a Petri dish and stored at 4 and 30 �C,

and then the fungal contamination level was determined. As shownin Fig. 5 and Table 5, the AST18-added yogurt showed an acceptablestate according Table 1 and showed no fungal growth duringstorage at 4 �C. Two of the three blank samples were contaminatedwith various types of fungi including mould and yeast.

As shown in Table 6, the blank group was contaminated withfungi at the 6th day during storage at 30 �C, whereas the 2% and 4%AST18-added yogurt samples showed contamination at the 10thday. The 6% and 8% AST18-added yogurt showed contamination atthe 14th day as well. All the samples were contaminated with fungiat the 18th day.

3.4.2. Mould-proof accelerated testingYogurt (20mL)was added to a sterilised Petri dish, and the spore

of Penicillium sp. was inoculated with an inoculating loop (60e80spores per container). The yogurt was placed in a Petri dish andstored in 4 and 30 �C, after which the fungal contamination levelwas determined.

Fig. 6 and Table 7 show that, the AST18-added yogurt showed nofungal growth during storage at 4 �C. The blank group wascontaminated with Penicillium sp. at the 10th day.

Table 6Preservation period experiment on different inoculums of AST18-added yogurt at30 �C.

Inoculums Time (day)

2 6 10 14 18 22

2% 0 0 1 3 3 34% 0 0 1 3 3 36% 0 0 0 1 3 38% 0 0 0 2 3 3Blank 0 1 3 3 3 3

The digits stand for the numbers of samples with fungal growth (each inoculum hadthree parallel samples).

Fig. 6. Growth of Penicillium sp. in 2% AST18-added yogurt and blank samples at 4 �C(the 21st day).

Table 7Growth of Penicillium sp. in different inoculums of AST18-added yogurt at 4 �C.

Inoculums Time (day)

2 6 10 14 18 22

2% 0 0 0 0 0 04% 0 0 0 0 0 06% 0 0 0 0 0 08% 0 0 0 0 0 0Blank 0 0 2 3 3 3

The digits stand for the numbers of samples with fun gal growth (each inoculum hadthree parallel samples).

Table 8The growth of Penicillium sp. in different inoculums of AST18-added yogurt at 30 �C.

Inoculums Time (day)

2 6 10 14 18 22

2% 0 3 3 3 3 34% 0 3 3 3 3 36% 0 3 3 3 3 38% 0 3 3 3 3 3Blank 3 3 3 3 3 3

The digits stand for the numbers of samples with fungal growth (each inoculum hadthree parallel samples).

H. Li et al. / Food Control 34 (2013) 675e680 679

Fig. 7 and Table 8 illustrate that the blank group was contami-natedwith Penicillium sp. at the 2nd day during storage at 30 �C andthe AST18-added yogurt was contaminated with Penicillium sp. atthe 6th day. The morphology of Penicillium sp. in AST18-addedyogurt was small, and no typical turquoise mycelium and sporewere observed (Fig. 7). Its morphology in the blank groupwas largeand a green-yellow metabolite was produced.

Fig. 7. Mouldeproof accelerated testing of 2% AST18-

4. Discussion

Antifungal strain L. casei AST18, previously isolated from atraditional Chinese dairy product, was tested for its potential asprotective culture in yogurt. As in a previous study, Penicillium sp.isolated from spoiled cheese, was sensitive to the culture of theL. casei AST18 (Li et al., 2012).We used Penicillium sp. as an indicatorstrain. The addition of L. casei AST18 completely inhibited thegrowth of Penicillium sp. at 4 �C. The challenge tests (Fig. 5) alsoshowed that L. casei AST18 inhibited the growth of other corruptingfungi. These fungi such as Penicillium species, Candida famata andK. Marxianus, regularly occur in yogurt and dairy products (Fleet,1990). In mould proof accelerated testing at 30 �C, Penicillium sp.grew both in the blank and AST18-added groups, but a significantdifference in Penicillium sp. growth conditions was found (Fig. 7).The colony morphology of Penicillium sp. in 2% AST18-added yogurtwas small, and no green-yellow metabolite was produced. A lot ofresearchers have reported that LAB can inhibit mycotoxin produc-tion (Dalie, Deschamps, & Richard-Forget, 2010). Wiseman andMarth (1981) added the spores of Aspergillus parasiticus to a 13-day-old culture of Lactococcus Lactis and observed the entirerepression of aflatoxin production.

LAB are well known as starter cultures in the manufacture ofdairy products, such as acidophilus milk, yogurt, buttermilk, cot-tage cheeses, hard cheeses and soft cheeses. LAB have a GRASstatus, and approximately 60% of the diet in many developingcountries consists of fermented foods (Stiles, 1996). The additionof L. casei AST18 did not affect the sensory quality of the yogurtand increased the number of viable cells in the yogurt samples.The use of L. casei AST18 as a biocontrol agent inhibited the growthof corrupting fungi in the yogurt. Schnurer and Magnusson (2005)revealed that three mechanisms may explain the antifungal and

added and blank samples at 30 �C (the 4th day).

H. Li et al. / Food Control 34 (2013) 675e680680

antimicrobial efficiency of LAB: the yield of organic acid, compe-tition for nutrients and production of antagonistic compounds.The antifungal compounds isolated from LAB fermentation cul-tures are mainly low-molecular mass metabolites these com-pounds are lactic acids, acetic acid, phenyllactic acid (Gerez,Torino, Rollan, & Fontdevaldez, 2009; Lavermicocca et al., 2000;Magnusson, Strom, Roos, Sjogren, & Schnurer, 2003; Strom,Sjogren, Broberg, & Schnurer, 2002), propionic acid, proteina-ceous (Lavermicocca, Valerio, & Visconti, 2003) and cyclic dipep-tide (Dalbello et al., 2007; Rouse, Vaughan & van Sinderen, 2008;Yang & Chang, 2010). Lactic acid and cyclo-(Leu-Pro) are theantifungal compounds identified in L. casei AST18 (Li et al., 2012).However, given that antifungal activities are observed in otherfractions, more antifungal compounds are believed to be presentin addition to the compounds detected. The purification of anti-fungal compounds is complicated and the amount of detectedcompounds is limited. The direct use of antifungal strains asprotective cultures presents important application value to thefood industry. Developing natural alternatives, such as biocontrolagents, to chemical preservation and protective cultures is apromising route for the biological control of spoilage microor-ganisms (Liu & Tsao, 2009).

To the best of our knowledge, this study is the first to system-atically describe a strain of L. casei with antifungal properties as abioprotective culture in yogurt.

Acknowledgement

This research was supported by the National Science andTechnology Support Program of the National Twelfth Five-Year Plan(2012BAD29B03-07) and Fundamental Research Funds for CentralPublic Welfare Research Institutes (0032012019).

References

Belal Jamal, M., & Zaiton, H. (2011). Screening of lactic acid bacteria for antifungalactivity against Aspergillus oryzae. American Journal of Applied Sciences, 8(5),447e451.

Bernardeau, M., Vernoux, J. P., Henri-Dubernet, S., & Gueguen, M. (2008). Safetyassessment of dairy microorganisms: the Lactobacillus genus. InternationalJournal of Food Microbiology, 126(3), 278e285.

Brosnan, B., Coffey, A., Arendt, E. K., & Furey, A. (2012). Rapid identification, by use ofthe LTQ Orbitrap hybrid FT mass spectrometer, of antifungal compounds pro-duced by lactic acid bacteria. Analytical and Bioanalytical Chemistry, 403(10),2983e2995.

Dalbello, F., Clarke, C., Ryan, L., Ulmer, H., Schober, T., Strom, K., et al. (2007).Improvement of the quality and shelf life of wheat bread by fermentation withthe antifungal strain Lactobacillus plantarum FST 1.7. Journal of Cereal Science,45(3), 309e318.

Dalie, D. K. D., Deschamps, A. M., & Richard-Forget, F. (2010). Lactic acid bacteria epotential for control of mould growth and mycotoxins: a review. Food Control,21(4), 370e380.

Dave, R. I., & Shah, N. P. (1997). Viability of yoghurt and probiotic bacteria in yo-ghurts made from commercial starter cultures. International Dairy Journal, 7(1),31e41.

Delavenne, E., Ismail, R., Pawtowski, A., Mounier, J., Barbier, G., & Le Blay, G. (2013).Assessment of lactobacilli strains as yogurt bioprotective cultures. Food Control,30(1), 206e213.

Filtenborg, O., Frisvad, J., & Thrane, U. (1996). Moulds in food spoilage. InternationalJournal of Food Microbiology, 33, 17.

Fleet, G. H. (1990). Yeast in dairy products. Journal of Applied Bacteriology, 68(3),199e212.

Gerez, C., Torino, M., Rollan, G., & Fontdevaldez, G. (2009). Prevention of breadmould spoilage by using lactic acid bacteria with antifungal properties. FoodControl, 20(2), 144e148.

Lavermicocca, P., Valerio, F., Evidente, A., Lazzaroni, S., Corsetti, A., & Gobbetti, M.(2000). Purification and characterization of novel antifungal compounds fromthe sourdough Lactobacillus plantarum strain 21B. Applied and EnvironmentalMicrobiology, 66(9), 4084e4090.

Lavermicocca, P., Valerio, F., & Visconti, A. (2003). Antifungal activity of phenyllacticacid against molds isolated from bakery products. Applied and EnvironmentalMicrobiology, 69(1), 634e640.

Li, H., Liu, L., Zhang, S., Cui, W., & Lv, J. (2012). Identification of antifungal compoundsproduced by Lactobacillus casei AST18. Current Microbiology, 65(2), 156e161.

Li, H., Liu, L., Zhang, S., Sun, Z., Kong, F., & Lv, J. (2011). Screening of antifungal lacticacid bacteria and the study of fermentation properties. China Dairy Industry,39(3), 4e6.

Liu, S.-Q., & Tsao, M. (2009). Biocontrol of dairy moulds by antagonistic dairy yeastDebaryomyces hansenii in yoghurt and cheese at elevated temperatures. FoodControl, 20(9), 852e855.

Lowe, D. P., & Arendt, E. K. (2004). The use and effects of lactic acid bacteria inmalting and brewing with their relationships to antifungal activity, mycotoxinsand gushing: a review. Journal of the Institute of Brewing, 110(3), 163e180.

Magnusson, J., Strom, K., Roos, S., Sjogren, J., & Schnurer, J. (2003). Broad andcomplex antifungal activity among environmental isolates of lactic acid bac-teria. Fems Microbiology Letters, 219(1), 129e135.

Mayoral, M. B., Martin, R., Sanz, A., Hernandez, P. E., Gonzalez, I., & Garcia, T. (2005).Detection of Kluyveromyces marxianus and other spoilage yeasts in yoghurtusing a PCR-culture technique. International Journal of Food Microbiology, 105(1),27e34.

Ozturk, B. A., & Oner, M. D. (1999). Production and evaluation of yogurt withconcentrated grape juice. Journal of Food Science, 64(3), 530e532.

Penna, A. L. B., Gurram, S., & Barbosa-Canovas, G. V. (2006). Effect of high hydro-static pressure processing on rheological and textural properties of probioticlow-fat yogurt fermented by different starter cultures. Journal of Food ProcessEngineering, 29(5), 447e461.

Rouse, S.,H. D., Vaughan, A., & van Sinderen, D. (2008). Lactic acid bacteria withpotential to eliminate fungal spoilage in foods. Journal of Applied Microbiology,915e923.

Ryan, L. A. M., Dal Bello, F., & Arendt, E. K. (2008). The use of sourdough fermentedby antifungal LAB to reduce the amount of calcium propionate in bread. In-ternational Journal of Food Microbiology, 125(3), 274e278.

Salvador, A., & Fiszman, S. M. (2004). Textural and sensory characteristics of wholeand skimmed flavored set-type yogurt during long storage. Journal of DairyScience, 87(12), 4033e4041.

Schnurer, J., & Magnusson, J. (2005). Antifungal lactic acid bacteria as bio-preservatives. Trends in Food Science & Technology, 16(1e3), 70e78.

Stiles, M. E. (1996). Biopreservation by lactic acid bacteria. Antonie Van LeeuwenhoekInternational Journal of General and Molecular Microbiology, 70(2e4), 331e345.

Strom, K., Sjogren, J., Broberg, A., & Schnurer, J. (2002). Lactobacillus plantarumMiLAB 393 produces the antifungal cyclic dipeptides cyclo(L-Phe-L-Pro) andcyclo(L-Phe-trans-4-OH-L-Pro) and 3-phenyllactic acid. Applied and Environ-mental Microbiology, 68(9), 4322e4327.

Wiseman, D. W., & Marth, E. H. (1981). Growth and aflatoxin production byAspergillus parasiticus when in the presence of Streptococcus lactis. Mycopa-thologia, 73(1), 49e56.

Wuhjideligen, Sudun, & Miyamoto, T. (2011). Screening and identification of lacticacid bacteria from airag for antifungal activity. Journal of Animal and VeterinaryAdvances, 10(21), 2751e2757.

Yang, E. J., & Chang, H. C. (2010). Purification of a new antifungal compound pro-duced by Lactobacillus plantarum AF1 isolated from kimchi. International Journalof Food Microbiology, 139(1e2), 56e63.