Survival of micro‐organisms and organic acid profile of probiotic Cheddar cheese from buffalo milk during accelerated ripening

The study aimed to assess the impact of ripening at elevated temperatures on the survival of probiotic micro‐organisms and production of organic acids in Cheddar cheese. Cheese was manufactured from buffalo milk using lactococci starters along with different probiotic bacteria (Lactobacillus acidophilus LA‐5, Bifidobacterium bifidum Bb‐11 and Bifidobacterium longum BB536) as adjunct cultures. The cheeses were ripened at 4–6 °C or 12–14 °C for 180 days and examined for composition, organic acids and microbial survival. The production of organic acids was accelerated at 12–14 °C when compared to normal ripening temperatures. The probiotic bacteria increased production of lactic and acetic acids, compared to cheese made with lactococci alone. The survival of the mesophilic starters was significantly (P < 0.05) reduced in all the cheese samples ripened at the higher temperature. However, the probiotic bacteria remained viable (>7.0 log₁₀ cfu/g) throughout the 180 days of ripening, irrespective of temperature. It was concluded that Cheddar containing additional probiotic cultures can effectively be ripened at elevated temperatures without any adverse effects.     

Effects of Penicillium roqueforti and whey cheese on gross composition,microbiology and proteolysis of mould‐ripened Civil cheese during ripening

Four different types of mould‐ripened Civil cheese were manufactured. A defined (nontoxigenic) strain of a Penicillium roqueforti (SC 509) was used as the secondary starter with and without addition of the whey cheese (Lor); in parallel, secondary starter‐free counterparts were manufactured. Chemical composition, microbiology and proteolysis were studied during the ripening. The incorporation of whey cheese in the manufacture of mould‐ripened Civil cheese altered the gross composition and adversely affected proteolysis in the cheeses. The inoculated P. roqueforti moulds appeared to grow slowly on those cheeses, and little proteolysis was evident in all cheese treatments during the first 90 days of ripening. However, sharp increases in the soluble nitrogen fractions were observed in all cheeses after 90 days. Microbiological analysis showed that the microbial counts in the cheeses were at high levels at the beginning of ripening, while their counts decreased approximately 1–2 log cfu/g towards the end of ripening.     

Proteolytic pattern and organic acid profiles of probiotic Cheddar cheese as influenced by probiotic strains of Lactobacillus acidophilus,Lb. paracasei,Lb. casei or Bifidobacterium sp.

Cheddar cheeses were produced with starter lactococci and Bifidobacterium longum 1941, B. lactis LAFTI^® B94, Lactobacillus casei 279, Lb. paracasei LAFTI^® L26, Lb. acidophilus 4962 or Lb. acidophilus LAFTI^® L10 to study the survival of the probiotic bacteria and the influence of these organisms on proteolytic patterns and production of organic acid during ripening period of 6 months at 4 °C. All probiotic adjuncts survived the manufacturing process of Cheddar cheese at high levels without alteration to the cheese-making process. After 6 months of ripening, cheeses maintained the level of probiotic organisms at >8.0 log₁₀ cfu g⁻¹ with minimal effect on moisture, fat, protein and salt content. Acetic acid concentration was higher in cheeses with B. longum 1941, B. lactis LAFTI^® B94, Lb. casei 279 and Lb. paracasei LAFTI^® L26. Each probiotic organism influenced the proteolytic pattern of Cheddar cheese in different ways. Lb. casei 279 and Lb. paracasei LAFTI^® L26 showed higher hydrolysis of casein. Higher concentrations of free amino acids (FAAs) were found in all probiotic cheeses. Although Bifidobacterium sp. was found to be weakly proteolytic, cheeses with the addition of those strains had highest concentration of FAAs. These data thus suggested that Lb. acidophilus 4962, Lb. casei 279, B. longum 1941, Lb. acidophilus LAFTI^® L10, Lb. paracasei LAFTI^® L26 and B. lactis LAFTI^® B94 can be applied successfully in Cheddar cheese.     

Assessing the proteolytic and lipolytic activities of single strains of mesophilic lactobacilli as adjunct cultures using a Caciotta cheese model system

Seventeen strains of mesophilic lactic acid bacteria, isolated from cheese (non-starter lactic acid bacteria, NSLAB) or sourdough, were used individually as adjunct cultures in a Caciotta cheese model system. Adjunct cultures were monitored by randomly amplified polymorphic DNA analysis and their cell counts mainly varied from ca. 9.0 to 8.0 log cfu g⁻¹ throughout 36 days of ripening. Adjunct cultures influenced differently cheese proteolysis. Both NSLAB and sourdough strains caused an extensive secondary proteolysis; however, some NSLAB strains produced the highest concentration of free amino acids. Principal component analysis (PCA) differentiated cheeses manufactured with NSLAB strains Lactobacillus parabuckneri B₉F_ST, Lb. paracasei B₆₁F₅, Lb. curvatus 2768 and Lb. rhamnosus ATCC 7469 based on the accumulation of Lys, Glu, Phe, Hist, Asp and Met. Assessment of cheese lipolysis showed that: (i) highest concentrations of free fatty acids (FFA) were found with NSLAB strains Lb. rhamnosus ATCC 7469 and Lb. casei subsp. pseudoplantarum 2742 (ca. 10 500 mg kg⁻¹); (ii) PCA differentiated cheeses manufactured with NSLAB strains Lb. rhamnosus ATCC 7469 and Lb. casei subsp. pseudoplantarum 2742 based on the accumulation of palmitic (C16:0) and linoleic (C18:2) acids, and those with Lb. curvatus 2768 and Lb. parabuckneri B₉F_ST based on the high concentration of short chain FFA; (iii) the cheese made with sourdough strain Lb. sanfranciscensis CB1 had the highest levels of unsaturated FFA.     

Nonstarter lactic acid bacteria biofilms and calcium lactate crystals in Cheddar cheese

A sanitized cheese plant was swabbed for the presence of nonstarter lactic acid bacteria (NSLAB) biofilms. Swabs were analyzed to determine the sources and microorganisms responsible for contamination. In pilot plant experiments, cheese vats filled with standard cheese milk (lactose:protein = 1.47) and ultrafiltered cheese milk (lactose:protein = 1.23) were inoculated with Lactococcus lactis ssp. cremoris starter culture (8 log cfu/mL) with or without Lactobacillus curvatus or Pediococci acidilactici as adjunct cultures (2 log cfu/mL). Cheddar cheeses were aged at 7.2 or 10°C for 168 d. The raw milk silo, ultrafiltration unit, cheddaring belt, and cheese tower had NSLAB biofilms ranging from 2 to 4 log cfu/100 cm². The population of Lb. curvatus reached 8 log cfu/g, whereas P. acidilactici reached 7 log cfu/g of experimental Cheddar cheese in 14 d. Higher NSLAB counts were observed in the first 14 d of aging in cheese stored at 10°C compared with that stored at 7.2°C. However, microbial counts decreased more quickly in Cheddar cheeses aged at 10°C compared with 7.2°C after 28 d. In cheeses without specific adjunct cultures (Lb. curvatus or P. acidilactici), calcium lactate crystals were not observed within 168 d. However, crystals were observed after only 56 d in cheeses containing Lb. curvatus, which also had increased concentration of d(−)-lactic acid compared with control cheeses. Our research shows that low levels of contamination with certain NSLAB can result in calcium lactate crystals, regardless of lactose:protein ratio.     

Adherence of probiotic bacteria to human colon epithelial cells and inhibitory effect against enteric pathogens – In vitro study

The aim of this study was to determine the anti‐adherence properties of three probiotic lactobacillus strains (Lb. rhamnosus 0900, Lb. rhamnosus 0908 and Lb. casei 0919), and their mixture against pathogens: Escherichia coli ATCC 10536, Salmonella enterica serovar Typhimurium ATCC 14028 and Candida albicans ATCC 10231 using Caco‐2 human colon adenocarcinoma cells. All strains of lactobacilli and the probiotic mixture to the greatest extent inhibited adherence of S. Typhimurium, up to 91%. Lb. rhamnosus 0900 inhibited E. coli by 75.9%, and Lb. casei 0919 decreased adherence of C. albicans by 49%. All pathogens activated the adherence of the mixture of probiotic bacteria.     

Viability of the Lactobacillus rhamnosus HN001 Probiotic Strain in Swiss‐ and Dutch‐Type Cheese and Cheese‐Like Products

The objective of this study was to determine the viability of the probiotic Lactobacillus rhamnosus HN001 in Swiss‐type and Dutch‐type cheese and cheese‐like products (milk fat is substituted by stearin fraction of palm fat) during manufacture, ripening, and storage. The use of the probiotic L. rhamnosus HN001 in Dutch‐type cheese and cheese‐like products significantly (P = 0.1) changed their chemical composition (protein and fat content) and an insignificant increase (approximately 1.6% in cheese‐like products and approximately 0.3% in cheese) in yield. L. rhamnosus HN001 did not affect the rate of changes in the pH of ripened cheese and cheese‐like products. A minor increase in probiotic counts was observed in initial stages of production and were partially removed with whey. Ripened cheese and cheese‐like products were characterized by high survival rates of probiotic bacteria which exceeded 8 log CFU/g after ripening. An insignificant reduction in the number of viable probiotic cells was noted during storage of Swiss‐type and Dutch‐type cheese, whereas a significant increase in probiotic cell counts was observed in cheese‐like products during storage.     

Use of high pressure treatment to attenuate starter bacteria for use as adjuncts for Cheddar cheese manufacture

Attenuated starter bacteria cannot produce acid during cheese manufacture, but contain enzymes that contribute to cheese ripening. The aim of this study was to investigate attenuation of starter bacteria using high pressure treatment, for use in combination with a primary starter for Cheddar cheese manufacture, and to determine the effect of such adjunct cultures on secondary proteolysis during ripening. Lactococcus lactis ssp. cremoris HP and L. lactis ssp. cremoris 303 were attenuated by pressure treatment at 200 MPa for 20 min at 20 °C. Cheddar cheese was manufactured using untreated cultures of both these starter strains, either alone or in combination with their high pressure-treated equivalents. High pressure-treated starters did not produce acid during cheese manufacture and starter counts in cheeses manufactured using high pressure-treated starter did not differ from those of the controls. Higher levels of cell lysis were apparent in cheese manufactured using high pressure-treated strains than in the controls after 26 d of ripening. Small differences were observed in the peptide profiles of cheeses, analysed by reversed-phase HPLC; cheeses manufactured using high pressure-treated starters also had slightly higher levels of amino acids than the relevant controls. Overall, addition of high pressure-treated starter bacteria as a secondary starter culture accelerated secondary proteolysis in Cheddar cheese.

Industrial relevance

Attenuated starters provide extra pool of enzymes, which can influence cheese ripening, without affecting the cheese making schedule. This paper presents an alternative method for attenuation of starter bacteria using high pressure treatment and their subsequent use to accelerate secondary proteolysis in Cheddar cheese during ripening.     

Manufacture of low-fat Cheddar cheese by exopolysaccharide-producing Lactobacillus plantarum JLK0142 and its functional properties

This study aimed to evaluate the effect of exopolysaccharide (EPS)-producing Lactobacillus plantarum JLK0142 on the ripening characteristics and in vitro health-promoting benefits of low-fat Cheddar cheese. Three batches of cheese were made by employing a non-EPS–producing cheese starter (control), in combination with Lb. plantarum JLK0142 as an adjunct and the purified EPS as an ingredient. Lactobacillus plantarum JLK0142 survived well in cheese, with counts of 7.99 log cfu/g after 90 d of ripening. All experimental cheeses (with adjunct culture or EPS ingredient) had higher moisture, proteolysis, and sensory scores, and lower hardness and cohesiveness compared with the control cheese. Water-soluble extracts from the experimental cheeses outperformed that of the control in scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), and hydroxyl radicals, and inhibiting α-amylase, angiotensin-converting enzyme, and HT-29 tumor cell growth. Therefore, incorporation of the EPS-producing culture of Lb. plantarum JLK0142 is promising for improvement of low-fat cheese quality and bioactivities.     

Prato cheese as suitable carrier for Lactobacillus acidophilus La5 and Bifidobacterium Bb12

To assess Prato cheese as suitable carrier for probiotic bacteria, four cheeses were produced. Control cheese contained only starter culture, whereas the others contained starter culture and the probiotic cultures Lactobacillus acidophilus La5 and Bifidobacterium Bb12 either separately or in combination. Bacterial viability, physicochemical composition, proteolysis, and texture profile were assessed over 60 days of storage. The addition of microorganisms together or separately did not affect the characteristics of Prato cheese. On storage, the cheeses showed increased proteolysis, lower firmness, and the probiotic cheeses presented counts higher than 10⁶ cfu g⁻¹. The viability of probiotics during in vitro gastrointestinal simulation, including the effect of the cheese matrix, was also assessed. The probiotic bacteria showed resistance to loss of viability during in vitro gastrointestinal simulation.     

Bacillus and Paenibacillus species associated with extended shelf life milk during processing and storage

Characterisation of spore formers associated with extended shelf life milk was performed by analysing the bacteriological quality of milk samples collected at various processing stages and during storage. Isolates were identified with MALDI‐TOF‐MS. Milk had spore counts <2 log₁₀ cfu/mL and 4 log₁₀ cfu/mL during processing and storage, respectively. Bacillus pumilus dominated the bacterial population. Bacterial species were inoculated into sterile milk for a shelf life study, and the population change was observed over 42 days at 7 °C. Although the extended shelf life milk process was effective in reducing bacterial counts and species diversity, the presence of Bacillus cereus shows a potential safety problem in extended shelf life milk.     

The effect of sodium reduction with and without potassium chloride on the survival of Listeria monocytogenes in Cheddar cheese

Sodium chloride (NaCl) in cheese contributes to flavor and texture directly and by its effect on microbial and enzymatic activity. The salt-to-moisture ratio (S/M) is used to gauge if conditions for producing good-quality cheese have been met. Reductions in salt that deviate from the ideal S/M range could result in changing culture acidification profiles during cheese making. Lactococcus lactis ssp. lactis or Lc. lactis ssp. cremoris are both used as cultures in Cheddar cheese manufacture, but Lc. lactis ssp. lactis has a higher salt and pH tolerance than Lc. lactis ssp. cremoris. Both salt and pH are used to control growth and survival of Listeria monocytogenes and salts such as KCl are commonly used to replace the effects of NaCl in food when NaCl is reduced. The objectives of this project were to determine the effects of sodium reduction, KCl use, and the subspecies of Lc. lactis used on L. monocytogenes survival in stirred-curd Cheddar cheese. Cheese was manufactured with either Lc. lactis ssp. lactis or Lc. lactis ssp. cremoris. At the salting step, curd was divided and salted with a concentration targeted to produce a final cheese with 600 mg of sodium/100 g (control), 25% reduced sodium (450 mg of sodium/100 g; both with and without KCl), and low sodium (53% sodium reduction or 280 mg of sodium/100 g; both with and without KCl). Potassium chloride was added on a molar equivalent to the NaCl it replaced to maintain an equivalent S/M. Cheese was inoculated with a 5-strain cocktail of L. monocytogenes at different times during aging to simulate postprocessing contamination, and counts were monitored over 27 or 50 d, depending on incubation temperature (12 or 5°C, respectively). In cheese inoculated with 4 log₁₀ cfu of L. monocytogenes/g 2 wk after manufacture, viable counts declined by more than 3 log₁₀ cfu/g in all treatments over 60 d. When inoculated with 5 log₁₀ cfu/g at 3 mo of cheese age, L. monocytogenes counts in Cheddar cheese were also reduced during storage, but by less than 1.5 log₁₀ cfu/g after 50 d. However, cheese with a 50% reduction in sodium without KCl had higher counts than full-sodium cheese at the end of 50 d of incubation at 4°C when inoculated at 3 mo. When inoculated at 8 mo postmanufacture, this trend was only observed in 50% reduced sodium with KCl, for cheese manufactured with both cultures. This enhanced survival for 50% reduced-sodium cheese was not seen when a higher incubation temperature (12°C) was used when cheese was inoculated at 3 mo of age and monitored for 27 d (no difference in treatments was observed at this incubation temperature). In the event of postprocessing contamination during later stages of ripening, L. monocytogenes was capable of survival in Cheddar cheese regardless of which culture was used, whether or not sodium had been reduced by as much as 50% from standard concentrations, or if KCl had been added to maintain the effective S/M of full-sodium Cheddar cheese.     

MODELLING of TIME-TEMPERATURE EFFECTS ON BACTERIA POPULATIONS DURING COOLING of CHEDDAR CHEESE BLOCKS1

Differences in cooling rate of Cheddar cheese from pressing (35C) to aging temperature (3.5–12C) has been reported to be responsible for flavor variation within a production lot. During aging, starter and nonstarter bacteria contribute extensively to flavor quality. Temperature effects on these bacteria were quantified using cheese from a local processor. At day 1, starter counts were 8 × 10⁷ cfu/g but as aging continued, starter counts decreased and non-starters became dominant. At 35C, starter counts reached 3 × 10⁶ cfu/g by day 3 and were below 10⁶ cfu/g by day 5. At 25, 20, 15 and 12C, starter bacteria were below 10⁶ cfu/g by day 10, 20, 24 and 40, respectively. Nonstarter counts, initially at 10⁴ cfu/g, reached = 10⁸ cfu/g at increasingly shorter times with higher temperatures. Kinetic analysis of growth in cheese and in a liquid medium suggested the possibility of diffusion growth limitations in cheese. Computer simulations for the growth of nonstarters suggests the individual cooling of small blocks (18 kg) would reduce the contribution of nonstarter counts to Cheddar cheese aging.     

Influence of reuterin-producing Lactobacillus reuteri coupled with glycerol on biochemical,physical and sensory properties of semi-hard ewe milk cheese

The biochemical, physical and sensory characteristics of ewe milk cheeses made with reuterin-producing Lactobacillus reuteri and glycerol (substrate for reuterin production) were assessed. Cheese made with lactococci starter (CTRL), cheese made with starter and L. reuteri (SLR), and cheese made with starter, L. reuteri and 30 mM glycerol (SLR-G) were manufactured. L. reuteri reached counts above 7 log cfu/g on day 1. Lactococci survival was enhanced in SLR cheese without affecting cheese pH, dry matter, proteolysis, concentration of most free amino acids (FAA), textural and most color parameters, or sensory characteristics. In situ production of reuterin by L. reuteri was only detected in SLR-G cheese, decreasing LAB counts although acidification remained unaffected. SLR-G cheese showed higher values of cell free aminopeptidase activity, overall proteolysis and FAA, particularly glutamic acid, than CTRL and SLR cheeses. The addition of L. reuteri-glycerol resulted in lower hardness and elasticity values in SLR-G cheese and influenced its L*, a* and b* color parameters. However, these changes, which were detected by instrumental analysis, did not affect the sensory scores for texture and color quality of SLR-G cheese, and it received the highest scores for taste quality. Our results suggest that L. reuteri-glycerol may provide a suitable system to release the antimicrobial reuterin in cheese without affecting negatively its sensory characteristics.     

Cream cheese as a symbiotic food carrier using Bifidobacterium animalis Bb‐12 and Lactobacillus acidophilus La‐5 and inulin

The stability of cream cheeses as a symbiotic food carrier, through supplementation with different concentrations of probiotic bacteria Bifidobacterium animalis Bb‐12 and Lactobacillus acidophilus La‐5 and the prebiotic ingredient inulin was investigated. Physicochemical parameters, pH values, total solids, fat and protein levels and the viable counts of the starter lactic culture Streptococcus thermophilus and probiotic cultures, were carried out at 1, 15, 30 and 45 days of refrigerated storage (8 ± 0.5 °C). Different physicochemical characteristics were observed in all formulations. S. thermophilus showed good viability in all the trials (6.66–9.38 log cfu/g), whereas B. animalis remained above 6 log cfu/g in all the trials during the period evaluated. However, L. acidophilus showed an accentuated decline, registering values of 3.1 log cfu/g at the end of the period studied. The results suggested that cream cheese was an adequate food matrix for supplementation with probiotic bacteria, in particular B. animalis, and the prebiotic ingredient, showing potential as a symbiotic food.     

Probiotic Cheddar cheese: Influence of ripening temperatures on survival of probiotic microorganisms, cheese composition and organic acid profiles

Bifidobacterium longum 1941, Bifidobacterium animalis subsp. lactis LAFTI^®B94 (B94), Lactobacillus casei 279, Lb. casei LAFTI^®L26 (L26), Lactobacillus acidophilus 4962 or Lb. acidophilus LAFTI^®L10 (L10) were used as an adjunct in the production of Cheddar cheeses which were ripened for 24 wk at 4 and 8 °C. Effects of ripening temperatures on survival of starter lactococci and probiotic microorganisms, pH and composition of cheeses and production of organic acids were examined. The counts of starter lactococci in cheeses produced with B. animalis B94, Lb. casei L26 or Lb. acidophilus 4962 ripened at 8 °C were significantly lower than those ripened at 4 °C (P < 0.05) at 24 wk. Probiotic microorganisms remained viable (>7.50 log₁₀ CFU/g) at the end of 24 wk and their viability was not affected by the ripening temperatures. There were significant effects of the type of probiotic microorganisms used, ripening time, ripening temperatures and their interactions on the concentration of lactic and acetic acids in the cheeses (P < 0.05). The acetic acid concentration in cheeses made with Bifidobacterium sp. or Lb. casei sp. was significantly higher than that of the control cheese (P < 0.05). Citric, propionic and succinic acids contents of the cheeses were not significantly affected by the type of probiotic microorganisms or ripening temperatures (P > 0.05).     

Proteolysis of reconstituted goat whey fermented by Streptococcus thermophilus in co‐culture with commercial probiotic Lactobacillus strains

Reconstituted goat whey was fermented with the starter Streptococcus thermophilus TA‐40 in co‐culture with four probiotic adjuncts (independent treatments): Lactobacillus casei BGP93 (T1), Lactobacillus paracasei BGP1 (T2), Lb. paracasei LPC37 (T3) and Lactobacillus rhamnosus LR32 (T4). Lactobacillus populations were higher than 7 log cfu/mL after fermentation and storage. Proteolysis increased significantly (P < 0.05) during fermentation in all trials. Relative amount of low‐molecular‐weight protein fractions (<6.5 kDa) increased in goat whey trials with T1, T3 and T4 during fermentation and storage. The goat whey powder was considered a potential substrate for starter and probiotic cultures, which raised the opportunities to upgrade this by‐product into a functional food.     

Chemical analysis and sensory evaluation of Cheddar cheese produced with Lactobacillus acidophilus,Lb. casei,Lb. paracasei or Bifidobacterium sp.

The sensory properties of probiotic Cheddar cheeses made using Lactobacillus acidophilus 4962, Lb. casei 279, Bifidobacterium longum 1941, Lb. acidophilus LAFTI^® L10, Lb. paracasei LAFTI^® L26 or B. lactis LAFTI^® B94 were assessed after ripening for 9 months at 4 °C. Probiotic cheeses except those with Lb. acidophilus 4962 were significantly different (P<0.05) from the control without any probiotic organism. Acceptability of probiotic cheese with Lb. casei 279 was significantly lower (P<0.05) than that of the control cheese with bitterness and sour-acid taste as the major defects. Concentration of acetic acid in probiotic cheeses was higher (P<0.05) than the control cheese. Vinegary scores did not influence the acceptability of the cheeses (P>0.05). Increased proteolysis in probiotic cheeses did not influence the Cheddary attribute scores (P>0.05). There were positive correlations (P<0.05) between the scores of bitterness and the level of water-soluble nitrogen.     

Release and identification of angiotensin-converting enzyme-inhibitory peptides as influenced by ripening temperatures and probiotic adjuncts in Cheddar cheeses

The aim of the study was to examine the release of angiotensin-converting enzyme (ACE)-inhibitory peptides in Cheddar cheeses made with starter lactococci and Bifidobacterium longum 1941, B. animalis subsp. lactis LAFTI^® B94, Lactobacillus casei 279, Lb. casei LAFTI^® L26, Lb. acidophilus 4962 or Lb. acidophilusLAFTI^® L10 during ripening at 4 and 8 °C for 24 weeks. ACE-inhibitory activity of the cheeses was maximum at 24 weeks. Cheeses made with the addition of Lb. casei 279, Lb. casei LAFTI^® L26 or Lb. acidophilus LAFTI^® L10 had significantly higher (P < 0.05) ACE-inhibitory activity than those without any probiotic adjunct after 24 weeks at 4 and 8 °C. The IC₅₀ of cheeses ripened at 4 °C was not significantly different (P > 0.05) to that ripened at 8 °C. The lowest value of the IC₅₀ (0.13 mg mL⁻¹) and therefore the highest ACE-inhibitory activity corresponded to the cheese with the addition of Lb. acidophilus LAFTI^® L10. Several ACE-inhibitory peptides were identified as κ-CN (f 96–102), α_s1-CN (f 1–9), α_s1-CN (f 1–7), α_s1-CN (f 1–6), α_s1-CN (f 24–32) and β-CN (f 193–209). Most of the ACE-inhibitory peptides accumulated at the early stage of ripening, and as proteolysis proceeded, some of the peptides were hydrolyzed into smaller peptides.     

Autolysis of selected Lactobacillus helveticus adjunct strains during Cheddar cheese ripening

Cheddar cheeses were manufactured on a pilot scale (500 L vats) with three different Lactobacillus helveticus strains, which showed varying degrees of autolysis, added as adjuncts to the starter. Autolysis of adjunct strains was monitored by reduction in cell numbers, level of intracellular enzymes released into the cheese, and by the consequent changes in the degree of proteolysis and concentration of free amino acids in the cheese. The flavour profiles of the cheeses at 6 months were also determined. Significant variation in viability of the Lb. helveticus strains, which showed a positive correlation with the indicators of autolysis, was observed. However, cheese manufactured with the most autolytic strain did not receive the highest flavour scores. The results indicate that whereas autolysis of adjunct strains is an important factor in Cheddar cheese flavour development, other factors also contribute to the overall flavour improvement observed.