Probiotic fermented beverages based on acid whey

Acid whey is a byproduct of cheesemaking that is difficult to use because of its low pH and less-favorable processing properties compared with rennet whey. The aim of this study was to evaluate the qualities of fermented beverages made using acid whey. In manufacturing the beverages, we used probiotic cultures Lactobacillus acidophilus LA-5 or Bifidobacterium animalis ssp. lactis BB-12. The production process included combining pasteurized acid whey with UHT milk, unsweetened condensed milk, or skim milk powder. We introduced milk to enrich casein content and obtain a product with characteristics similar to that of fermented milk drinks. The products were stored under refrigerated conditions (5 ± 1°C) for 21 d. During storage, we assessed the beverages' physicochemical properties and organoleptic characteristics. The properties of the beverages depended on their composition, microbial culture, and storage time. Beverages containing L. acidophilus had higher acidity, which increased during storage; the acidity of samples containing B. animalis was more stable. Beverages made with skim milk powder (La1 and Bb1) had higher acetaldehyde content, but this parameter decreased in all samples during storage. The hardness of the samples did not change during storage and was highest in beverage La3, made from whey, condensed milk, and L. acidophilus. Beverage La2, made from whey, milk, condensed milk, and L. acidophilus, had the best sensory properties. The whey beverages we developed provided a good medium for the probiotic bacteria; bacteria count throughout the storage period exceeded 8 log cfu/mL, distinctly higher than the minimum therapeutic dose.     

Effect of galactose metabolising and non-metabolising strains of Streptococcus thermophilus as a starter culture adjunct on the properties of Cheddar cheese made with low or high pH at whey drainage

Cheddar cheese was made using control culture (Lactococcus lactis subsp. lactis), or with control culture plus a galactose-metabolising (Gal⁺) or galactose-non-metabolising (Gal⁻) Streptococcus thermophilus adjunct; for each culture type, the pH at whey drainage was either low (pH 6.15) or high (pH 6.45). S. thermophilus affected the levels of residual lactose and galactose, and the volatile compound profile and sensory properties of the mature cheese (270 d) to an extent dependent on the drain pH and phenotype (Gal⁺ or Gal⁻). For all culture systems, reducing drain pH resulted in lower levels of moisture and lactic acid, a higher concentration of free amino acids, and higher firmness. The results indicate that S. thermophilus may be used to diversify the sensory properties of Cheddar cheese, for example from a fruity buttery odour and creamy flavour to a more acid taste, rancid odour, and a sweaty cheese flavour at high drain pH.     

X-ray irradiation as a valid technique to prolong food shelf life: The case of ricotta cheese

The sanitising effects of X-rays were studied on ricotta cheese at intensities of 0.5, 2 and 3 kGy, using products manufactured artisanally and industrially. Microbiological, sensory and pH evaluations were performed during refrigerated storage. The artisanal ricotta irradiated at the two highest intensities (2 and 3 kGy) remained acceptable for more than 20 days, whereas the untreated samples became unacceptable after only 3 days of storage. The shelf life of the product irradiated at 0.5 kGy was limited to 14 days, due to the appearance of sensory defects. The industrial product irradiated at all X-rays intensities recorded a significant shelf life prolongation up to 84 days compared with the control, which was rejected after 40 days due to sensory defects. The results show that X-ray treatment can significantly prolong the shelf life of ricotta cheese, boosting the marketability of this fresh dairy product far from the local production sites.     

Thermal inactivation of chymosin during cheese manufacture

The aspartic proteinase, chymosin (EC 3.4.23.4) is the principal milk clotting enzyme used in cheese production and is one of the principal proteolytic agents involved in cheese ripening. Varietal differences in chymosin activity, due to factors such as cheese cooking temperature, fundamentally influence cheese characteristics. Furthermore, much chymosin is lost in whey, and further processing of this by-product may require efficient inactivation of this enzyme, with minimal effects on whey proteins. In the first part of this study, the thermal inactivation kinetics of Maxiren 15 (a recombinant chymosin preparation) were studied in skim milk ultrafiltration permeate, whole milk whey and skim milk whey. Inactivation of chymosin in these systems (at pH 6.64) followed first order kinetics with a D45.5 value of 100 +/- 21 min and a z-value of 5.9 +/- 0.3 degrees C. D-Values increased linearly with decreasing pH from 6.64 to 6.2, while z-values decreased as pH decreased from 6.64 to 6.4, but were similar at pH 6.4 and 6.2. Subsequent determination of chymosin activity during manufacture of Cheddar and Swiss-type cheese showed good correlations between predicted and experimental values for thermal inactivation of chymosin in whey. However, both types of cheese curd exhibited relatively constant residual chymosin activity throughout manufacture, despite the higher cooking temperature applied in the manufacture of Swiss cheese. Electrophoretic analysis of slurries made from Cheddar and Swiss cheese indicated decreased proteolysis due to chymosin activity during storage of the Swiss cheese slurry, but hydrolysis of sodium caseinate by coagulant extracted from both cheese types indicated similar levels of residual chymosin activity. This may suggest that some form of conformational change other than irreversible thermal denaturation of chymisin takes place in cheese curd during cooking, or that some other physico-chemical difference between Swiss and Cheddar cheese controls the activity of chymosin during ripening.     

Yield,changes in proteolysis,and sensory quality of Prato cheese produced with different coagulants

The objective of this research was to compare the effect of 2 fungal proteases, one that is already commercially established as a milk-clotting agent and another produced at the laboratory scale, on Prato cheese composition, protein and fat recovery, yield, and sensory characteristics. Cheeses were produced according to the traditional protocol, using protease from the fungus Thermomucor indicae-seudaticae N31 and commercial coagulant from Rhizomucor spp. as clotting agents. A 2 × 6 factorial design with 3 replications was performed: 2 levels of coagulants and 6 levels of storage time. After 5, 12, 19, 33, 43, and 53 d of refrigerated storage (12°C), cheeses were monitored for proteolysis, firmness, and casein degradation by capillary electrophoresis. Sensory acceptance was evaluated after 29 d of manufacturing. The different coagulants did not statistically affect Prato cheese composition, protein and fat recovery, and yield. Both cheeses presented good sensory acceptance. Proteolysis increased and firmness decreased for both cheeses during the storage time, as expected for Prato cheese. Caseins were well separated by capillary electrophoresis and the results showed, with good resolution, that the cheeses exhibited similar protein hydrolysis profile. Both cheeses presented good sensory acceptance. The gathered data showed that the protease from T. indicae-seudaticae N31 presented similar action compared with the commercial enzyme, indicating its efficiency as clotting agent for Prato cheese manufacture.     

The effect of storage on nutritional,textural and sensory characteristics of creamy ricotta made from whey as well as cow's milk and goat's milk

The aim of this study was to develop a creamy ricotta using a mixture of goat and cow whey as the main ingredients, with the addition of whole goat and cow milk. The nutritional composition, texture and sensory characteristics of the ricotta cheese were evaluated over 14 days of refrigerated storage. There was a decrease in protein and ash content and pH changes during the assessed storage periods. The instrumental texture profile indicated that the creamy ricotta was easily deformable, with minimal inelasticity and a cohesive, soft and delicate texture. The medium‐ and long‐chain fatty acid content was higher than the short‐chain fatty acid content. The flavour and aroma of creamy ricotta were described by the panel as having a soft texture and wet appearance. The use of whey from goat and cow cheese in making creamy ricotta is feasible and does not cause negative impact in the final product.     

Effect of liquid whey protein concentrate–based edible coating enriched with cinnamon carbon dioxide extract on the quality and shelf life of Eastern European curd cheese

Fresh unripened curd cheese has long been a well-known Eastern European artisanal dairy product; however, due to possible cross-contamination from manual production steps, high moisture content (50–60%), and metabolic activity of present lactic acid bacteria, the shelf life of curd cheese is short (10–20 d). Therefore, the aim of this study was to improve the shelf life of Eastern European acid-curd cheese by applying an antimicrobial protein-based (5%, wt/wt) edible coating. The bioactive edible coating was produced from liquid whey protein concentrate (a cheese production byproduct) and fortified with 0.3% (wt/wt, solution basis) Chinese cinnamon bark (Cinnamomum cassia) CO₂ extract. The effect of coating on the cheese was evaluated within package-free (group 1) and additionally vacuum packaged (group 2) conditions to represent types of cheeses sold by small and big scale manufacturers. The cheese samples were examined over 31 d of storage for changes of microbiological (total bacterial count, lactic acid bacteria, yeasts and molds, coliforms, enterobacteria, Staphylococcus spp.), physicochemical (pH, lactic acid, protein, fat, moisture, color change, rheological, and sensory properties). The controlled experiment revealed that in group 1, applied coating affected appearance and color by preserving moisture and decreasing growth of yeasts and molds during prolonged package-free cheese storage. In group 2, coating did not affect moisture, color, or texture, but had a strong antimicrobial effect, decreasing the counts of yeasts and molds by 0.79 to 1.55 log cfu/g during 31 d of storage. In both groups, coating had no effect on pH, lactic acid, protein, and fat contents. Evaluated sensory properties (appearance, odor, taste, texture, and overall acceptability) of all samples were similar, indicating no effect of the coating on the flavor of curd cheese. The edible coating based on liquid whey protein concentrate with the incorporation of cinnamon extract was demonstrated to efficiently extend the shelf life of perishable fresh curd cheese, enhance its functional value, and contribute to a more sustainable production process.     

Application of bacteriocin-producing Enterococcus faecium isolated from donkey milk,in the bio-control of Listeria monocytogenes in fresh whey cheese

A total of 79 bacterial strains, previously isolated from donkey milk, were screened for their antimicrobial activity against several spoilage and foodborne pathogenic bacteria. Amongst them, 3 strains belonging to Enterococcus faecium displayed antimicrobial activity against Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus. Mass spectrometry analysis demonstrated that all enterococci used in this study produced peptides with masses consistent with those for enterocins A and B. The cell-free supernatants of the identified bacteriocin-producing enterococci were equally active over a wide range of pH and heat treatments making them excellent candidates for potential applications in bio-preservation. Bacteriocins produced by these strains were tested for their capability to control post-processing contamination and growth of L. monocytogenes during refrigerated storage of artificially contaminated fresh whey cheese. One strain was considered bactericidal while the other two were classified as bacteriostatic.     

Influence of starters on chemical, biochemical, and sensory changes in Turkish White-brined cheese during ripening

Turkish White-brined cheese was manufactured using Lactococcus strains (Lactococcus lactis ssp. lactis NCDO763 plus L. lactis ssp. cremoris SK11 and L. lactis ssp. lactis UC317 plus L. lactis ssp. cremoris HP) or without a starter culture, and ripened for 90 d. It was found that the use of starters significantly influenced the physical, chemical, biochemical, and sensory properties of the cheeses. Chemical composition, pH, and sensory properties of cheeses made with starter were not affected by the different starter bacteria. The levels of soluble nitrogen fractions and urea-PAGE of the pH 4.6-insoluble fractions were found to be significantly different at various stages of ripening. Urea-PAGE patterns of the pH 4.6-insoluble fractions of the cheeses showed that considerable degradation of α_s1-casein occurred and that β-casein was more resistant to hydrolysis. The use of a starter culture significantly influenced the levels of 12% trichloroacetic acid-soluble nitrogen, 5% phosphotungstic acid-soluble nitrogen, free amino acids, total free fatty acids, and the peptide profiles (reverse phase-HPLC) of 70% (vol/vol) ethanol-soluble and insoluble fractions of the pH 4.6-soluble fraction of the cheeses. The levels of peptides in the cheeses increased during the ripening period. Principal component and hierarchical cluster analyses of electrophoretic and chromatographic results indicated that the cheeses were significantly different in terms of their peptide profiles and they were grouped based on the use and type of starter and stage of ripening. Levels of free amino acid in the cheeses differed; Leu, Glu, Phe, Lys, and Val were the most abundant amino acids. Nitrogen fractions, total free amino acids, total free fatty acids, and the levels of peptides resolved by reverse phase-HPLC increased during ripening. No significant differences were found between the sensory properties of cheeses made using a starter, but the cheese made without starter received lower scores than the cheeses made using a starter. It was found that the cheese made with strains NCDO763 plus SK11 had the best quality during ripening. It was concluded that the use of different starter bacteria caused significant differences in the quality of the cheese, and that each starter culture contributed to proteolysis to a different degree.     

Development of goat cheese whey-flavoured beverages

Beverages made from goat cheese whey, flavoured with strawberry and peach pulp, were processed and submitted to physicochemical analysis and affective tests. The beverages exhibited similar values with respect to all the analyses of the proximate composition and little variation in pH and titratable acidity during refrigerated storage. They also showed low caloric value. For colour, aroma and consistency acceptability, there was no significant difference ( P > 0.05) among peach and strawberry flavoured samples. The flavour acceptability was higher for the strawberry beverage than for the peach one ( P = 0.05). A positive purchase intent for strawberry flavoured beverage was reported by 76% of the consumers, while 50% affirmed a similar intention for the peach-flavoured product. The beverages produced showed potential for commercialization, serving as an additional alternative product derived from goat milk, with minimal additional cost to the dairy plant.     

Viability of Salmonella enterica subsp. enterica during the preparation and cold storage of Egyptian soft cheeses and ice-cream

Changes occurring in the viability of Salmonella enterica subsp. enterica during the preparation and cold storage of Domiati cheese, Kariesh cheese and ice-cream were examined. A significant decrease in numbers was observed after whey drainage during the manufacture of Domiati cheese, but Salmonella remained viable for 13 weeks in cheeses prepared from milks with between 60 and 100 g/L NaCl; the viability declined in Domiati cheese made from highly salted milk during the later stages of storage. The method of coagulation used in the preparation of Kariesh cheese affected the survival time of the pathogen, and it varied from 2 to 3 weeks in cheeses made with a slow-acid coagulation method to 4–5 weeks for an acid-rennet coagulation method. This difference was attributed to the higher salt-in-moisture levels and lower pH values of Kariesh cheese prepared by the slow-acid coagulation method. A slight decrease in the numbers of Salmonella resulted from ageing ice-cream mix for 24 h at 0°C, but a greater reduction was evident after one day of frozen storage at −20°C. The pathogen survived further frozen storage for four months without any substantial change in numbers.     

Effects of different packaging systems on microbiological,sensory and peptide profile in fiordilatte cheese

Effects of different packaging systems on water soluble oligopeptide fractions in fiordilatte cheese during its refrigerated storage are described. The degradation of the main protein fractions and the characterization of peptides arising from caseins were monitored by nanoliquid chromatography and electrospray ionization ion trap mass spectrometry (MS) coupled with a bioinformatics approach based on the scoring distribution and a post-database search validation. Microbiological and sensory properties of fiordilatte samples packaged under different conditions were also evaluated in order to find possible correlations between quality decay of cheese and peptide profile. The various packaging solutions differently responded to the degradation processes, thus allowing to identify the three systems that better preserved cheese quality: the two active coated samples packaged under MAP with and without brine and the sample in brine acidified at pH 5. As far as the peptide profile is concerned, a dynamic evolution of hydrophilic peptides was observed belonging almost exclusively to β-casein that could be regarded as the primary substrate of proteolysis in fiordilatte cheese. Characteristic trends with maximum and minimum values at different times were observed, throughout the refrigerated storage, leading to continuous changes in the peptide composition. A reduction in levels of β-casein peptides was observed in all the samples compared to the control, for which no specific packaging treatments were adopted.     

INCIDENCE OF MYCOTOXIC MOLDS IN DOMESTIC AND IMPORTED CHEESES12

Domestic and imported cheeses were studied to determine the incidence of mycotoxin producing molds. The total incidence of molds in visibly non-moldy cheese was very low. Isolation of molds from plate counts, and directly from samples, showed that the major portion of the flora was made up of Penicillium species; 86% in domestic cheeses and 80% in imported cheeses. Many of the Penicillium isolates were capable of growing at low storage temperatures. Mold counts done at 5°C, and prolonged storage of cheese samples at 5°C indicated a potential for considerable mold growth on cheese during refrigerated storage. While the overall incidence of known mycotoxin producing molds was low, a number of potentialy toxic species were found, including P. cyclopium, P. viridicatum, A. flavus and A. ochraceus. These species accounted for 4.4% of all the isolates from domestic cheeses and 4.0% from imported cheeses. Screening of all mold isolates for production of several known mycotoxins showed that a number of isolates (14.1% of all molds in domestic cheeses and 11.5% in imported cheeses) were capable of producing certain mycotoxins including patulin, penicillic acid, ochratoxin A, citrinin and aflatoxins.     

Effect of high-pressure-processing on the microbiology,proteolysis, texture and flavour of Brie cheese during ripening and refrigerated storage

Brie cheeses were high pressure (HP)-treated at 400 or 600 MPa on days 14 or 21 after manufacture to prevent over-ripening. Lactic acid bacteria and Penicillium camemberti numbers declined markedly after HP treatment. In control cheese pH increased 2.0 units from day 21 to day 60, but less than 0.3 units in HP-treated cheeses. Cheeses treated at 600 MPa showed the maximum concentrations of residual caseins during refrigerated storage and control cheese the minimum concentrations. A 7.6-fold increase in hydrophobic peptides was recorded from day 21 to day 60 in control cheese and 0.8–1.6-fold increases in HP-treated cheeses. The maximum aminopeptidase activity was detected in control cheese, the highest free amino acid concentrations in cheeses treated at 400 MPa. The firmest texture was recorded for cheeses treated on day 14 at 400 or 600 MPa. HP-treated cheeses showed higher flavour quality scores than control cheese from day 60 onwards.     

Probiotic cheese production using Lactobacillus casei cells immobilized on fruit pieces

Lactobacillus casei cells were immobilized on fruit (apple and pear) pieces and the immobilized biocatalysts were used separately as adjuncts in probiotic cheese making. In parallel, cheese with free L. casei cells and cheese only from renneted milk were prepared. The produced cheeses were ripened at 4 to 6°C and the effect of salting and ripening time on lactose, lactic acid, ethanol concentration, pH, and lactic acid bacteria viable counts were investigated. Fat, protein, and moisture contents were in the range of usual levels of commercial cheeses. Reactivation in whey of L. casei cells immobilized on fruit pieces after 7 mo of ripening showed a higher rate of pH decrease and lower final pH value compared with reactivation of samples withdrawn from the remaining mass of the cheese without fruit pieces, from cheese with free L. casei, and rennet cheese. Preliminary sensory evaluation revealed the fruity taste of the cheeses containing immobilized L. casei cells on fruit pieces. Commercial Feta cheese was characterized by a more sour taste, whereas no significant differences concerning cheese flavor were reported by the panel between cheese containing free L. casei and rennet cheese. Salted cheeses scored similar values to commercial Feta cheese, whereas unsalted cheese scores were significantly lower, but still acceptable to the sensory panelists.     

Cottage cheese whey as an ingredient of cottage cheese dressing mixes

The objective of this study was to formulate and develop a good quality cottage cheese dressing using acid whey as the main ingredient. Up to 72% of cottage cheese whey was used in the dressing mixes. The percentage of fat (4.10–5.05%) and total solids (19.41–20.24%) approached the desired level and was within the legal limits for regular cottage cheese. Sensory evaluation scores for flavour, body/texture and appearance were not adversely affected by the use of acid whey. The sensory evaluation scores for all four products made with whey- or skimmed milk-based dressings were higher than the commercial control.     

Afuega’l Pitu Cheese Quality: Carbon Dioxide Addition to Refrigerated Milk in Acid-coagulated Cheesemaking

The suitability of milk preserved by refrigeration and CO₂ addition for the manufacture of Afuega’l Pitu, a Spanish acid-coagulated short-ripened cheese, was evaluated at pilot scale using an autochthonous cheese starter. Cheeses manufactured, after milk pasteurisation, from vacuum degasified refrigerated CO₂-treated samples (pH 6.2) were compared with two different control cheeses made from pasteurised milk either fresh or refrigerated. The multiplication and acidification capacity of lactic acid bacteria as well as the production of volatile compounds during cheesemaking and ripening were not affected by the previous refrigeration and CO₂-treatment of raw milk nor by the residual CO₂ still present in pasteurised milk after degasification and pasteurisation. Residual CO₂ retarded the proteolysis although no differences on proteolysis and sensory properties were detected at the optimum time of consumption (15 days) between cheeses made from CO₂-treated milk and those made from untreated control milk. CO₂-treatment effectively prevents the decrease in cheese yield caused by the microorganisms present in raw milk of poor microbial quality. These results support the interest of the CO₂-addition in preservation of milk for cheesemaking, specially when it has a high initial microbial load; the method can be satisfactorily used in the manufacture of Afuega’l Pitu cheese and may be extended to the production of other acid-coagulated cheeses.     

Volatile compounds and sensory changes after high pressure processing of mature “Torta del Casar” (raw ewe's milk cheese) during refrigerated storage

The main objective of this paper was to study the changes during refrigerated storage in the volatile compounds and the sensory characteristics of raw ewe's milk mature Torta del Casar cheese High Pressure Processing-treated (200 or 600 MPa for 5 or 20 min) on day 60 after manufacture. Most of the volatile compounds and sensory characteristics were significantly affected by the refrigerated storage and to a lesser extent by the HPP treatment. The 600 MPa HPP treatments caused a decrease in the levels of the most abundant volatile compounds (acids and esters) and in bitterness scores on days 120 and 180. A significant effect was also found for some compounds, the overall flavour, and saltiness on day 240 after manufacture.Industrial relevance textHigh pressure processing treatments at 600 MPa applied to mature raw ewe's milk cheese such as “Torta del Casar” cheese could be an interesting option for the cheese industry to prevent some of the changes that occur during refrigerated storage that are related to over-ripening and excessive bitterness development. In addition, compared to the application of the treatment before maturation is completed, treating mature cheeses is convenient for the cheese industry because it provides the advantage of not requiring any unpackaging steps, which allows the food industry the commercialization of the cheeses without any additional packaging.