Cheese Manufacturing Process Research Articles

Two moments preserving sectional approach for an enzymatic coagulation equation

The coagulation process has found extensive applications in monitoring the evolution of aerosol and granule preparation in pharmaceutical sciences, blood clotting in biology, and cheese manufacturing due to the enzymes in the dairy industry. Among these, modeling the cheese manufacturing process is more challenging due to three indistinguishable sub-mechanisms: (a) enzymatic proteolysis, (b) coagulation, and (c) gelation, which occurs during the enzymatic coagulation of milk. The current study focuses on developing a sectional approach based on the cell average technique for monitoring the evolution of enzyme-induced coagulation of paracasein micelles over time. The proposed technique preserves two integral properties, such as total number and total volume in the system. The mathematical formulation of the proposed technique is very simple, easy to code, and has a robust implementation on any uniform and non-uniform grids. Due to the unavailability of the analytical solutions of the number density functions, the validation of the new proposed approach is done by extracting the new series solutions through the modification of the Homotopy perturbation method [Kaur et al., J. Phys. A 52(38), 385201 (2019)] and exact integral moments for several kernels. It has been shown that the new approach not only estimates the first two integral moments accurately but also computes the second-order moment with high precision without any specific measures. Moreover, domains of varying size grids are taken into account to analyze the convergence behavior of the average-size paracasein micelles formed in the system based on the zeroth and first moments.

Cheese whey and dairy manure anaerobic co-digestion at psychrophilic conditions: Technical and environmental evaluation

Cheese whey (CW) and dairy manure (DM) are the main residues from the dairy industry, both of which can led to significant negative environment impacts if not properly managed. However, their combined anaerobic digestion represents an opportunity to obtain bioenergy and a stabilised material as a soil improver on the farm. Biochemical potential of methane (BMP) assays were carried out at psychrophilic conditions (20 °C) to analyse the influence on biomethane production of different CW:DM mixtures (% w/w) at different of inoculum-to-substrate ratios (ISR). Based on the BMP results, a life cycle assessment (LCA) of the cheese manufacturing process was carried out considering two scenarios (i) considering the current process, where propane gas and electricity are used for cheese production (ii) the incorporation of the biogas generated in the cheese production process in the company. BMP results showed that the best mixture between CW and DM was 65:35 (weight basis) at an organic load of 0.6 gVS/L (ISR of X). The LCA showed that CW and DM anaerobic digestion allowed to reduce the cheese manufacturing carbon footprint from through the substitution of propane by the biogas produced, changing from 5.5 to 3.1 kg CO2-eq/kg cheese produced, which indicates that according to the monthly production (633.6 kg) it would stop emitting about 1519 kg CO2-eq, i.e. a saving in terms of emissions of approximately 43,6% of the total currently generated.

Explorando o queijo de leite de cabra: uma revisão sistemática das técnicas e inovações de produção (2013-2023)

Abstract The global demand for milk and dairy products is rising, with cow's milk dominating production. However, goat dairy products have gained attention due to their nutritional value and bioactive components. Goat milk, in particular, is priced attractively, leading to increased interest from producers and investors. Goat milk-based products like yogurt, cheese, and fermented milk are available in the market and prepared using advanced processing technologies. Goat milk's exceptional quality, nutritional composition, and adaptability make it a superior choice, containing essential minerals and vitamins. The gourmet market has elevated goat cheese to a refined culinary delight. Therefore, this systematic review aims to summarize the state of successful research on goat milk cheese production from 2013 to 2023. The bibliographic search was carried out in September 2023 in electronic databases of scientific journals, namely Google Scholar, Science Direct, PUBMED, SCIELO, and Web of Science. Twenty (20) articles were included to discuss results that addressed the research question, meeting the inclusion and exclusion criteria. The content presented provides a comprehensive overview of the cheese manufacturing process, encompassing stages such as filtration, pasteurization, addition of lactic cultures, coagulation (using various methods such as enzymatic, rennet, charcoal, or enzymes), cutting the curd, molding, salting, and maturation. The inclusion of bibliographic references further enhances understanding, highlighting the evolution of practices over time. These contributions are essential for improving the quality and efficiency of goat milk cheese production, offering valuable insights for researchers, producers, and industry enthusiasts.

Survey on husbandry and cheese manufacturing practices in small ruminants' farmhouse dairies in Central Italy.

Farmhouse cheeses made from raw ovine or caprine milk are very popular among the consumers not only in Italy but also overseas because of their unique organoleptic properties. These cheeses are usually manufactured, according to traditional methods, in small rudimental facilities adjacent to the farm where the achievement of satisfactory hygienic standards can be challenging. However, the lack of systematic data about farm management and the cheese manufacturing processes hampers the conduction of specific risk assessment studies. In order to fill the knowledge gaps, we collected relevant data, through a questionnaire - based survey, from 125 small ruminants' farmhouse dairies spread in Lazio. Results showed that 1.1% of registered farms process their own milk for the production of raw milk cheeses. Hand milking is still applied in almost half of them and most products are subject to a short ‑ to ‑ medium ripening period which might not be sufficient to reduce eventual pathogen load. Products are mainly sold directly to consumers on the farm premises. Our results suggest the need to support these artisan cheese producers in order to improve the production standards without altering the traditional cheesemaking practices. The reported data are also useful for specific risk assessment studies.

Causality Verification for the Correlation between the Presence of Nonstarter Bacteria and Flavor Characteristics in Soft-Type Ripened Cheeses.

Flavor characteristics of ripened cheese are established by various bacteria, such as lactic acid bacteria, Actinobacteria, and Proteobacteria, which spontaneously develop during the cheese-manufacturing process. We previously revealed the relationship between bacterial microbiota and flavor components in soft-type ripened cheeses by using a multiomics approach that combined metagenomics and metabolomics; however, we could not establish a causal relationship. This study aimed to substantiate the causal nature of the correlations revealed by the multiomics approach by using cheese-ripening tests with single isolate inoculation. The bacterial diversity and composition in surface mold-ripened cheeses from Japan and France varied, depending on the differences between the milks (pasteurized or raw), cheese positions (core or rind), and manufacturers. Although the volatile compounds did not clearly reflect the distinctive characteristics of the cheese samples, nonstarter lactic acid bacteria, Actinobacteria, and Proteobacteria positively correlated with ketones and sulfur compounds, as evidenced by a Spearman's correlation analysis. Cheese-ripening tests conducted after inoculation with single bacterial strains belonging to the above-mentioned taxa confirmed that these bacteria formed volatile compounds, in agreement with the correlations observed. In particular, various flavor compounds, such as acids, esters, ketones, and sulfur compounds, were detected in cheese inoculated with Pseudoalteromonas sp. TS-4-4 strain. These findings provide important insights into the role of nonstarter bacteria in the development of cheese flavor and into the effectiveness of the multiomics approach in screening for bacteria that can improve the quality of cheese products. IMPORTANCE Our previous study revealed that the existence of various bacteria, such as lactic acid bacteria, Actinobacteria, and Proteobacteria, clearly correlated with the abundance of flavor components, such as volatile compounds, in soft-type ripened cheeses via a multiomics approach that used 16S rRNA gene amplicon sequencing and headspace gas chromatography-mass spectrometry. However, this approach only showed correlations derived from statistical analyses rather than causal relationships. Therefore, in the present study, we performed cheese-ripening tests using nonstarter bacteria to substantiate the correlations revealed by the multiomics approach in soft-type ripened cheese. Our results suggest the capability of nonstarter bacteria, such as Proteobacteria, to impart flavor to cheese and the effectiveness of the multiomics approach in screening for microbial isolates that can improve the quality of cheese. Overall, our research provides new insights into the importance of bacteria in cheese production.

Effect of coagulants on the chemical and microbial quality of fresh cheese

This experiment was conducted to explore the effect of various types of coagulants on the chemical and microbiological quality of cheese made from fresh milk. Fresh cheese was manufactured using four different coagulants; microbial rennet (0.7%), lactic acid (1.5%), papaya latex (5 drops in 100 mL water) and calf rennet (100 g calf abomasum soaked overnight in 1000 mL mixture of water and milk in 3:1 ratio and then filtrate) under laboratory condition and analyzed for cheese yield, proximate composition, acidity, pH and coagulation time. In addition, standard plate count and coliform count was also performed. Result revealed that using microbial rennet as coagulant gave the maximum yield of cheese (225 g/Kg milk) followed by calf rennet and lactic acid, and papaya latex had the minimum value (215g/Kg milk) in this regard (p=0.013). Microbial rennet took the lowest time (22 min) to coagulate the milk which was 14-34 min less than that of the other coagulants, and lactic acid had the slowest (54 min) coagulating action in cheese manufacturing process (p=0.000). In addition, cheese that are manufactured by microbial rennet and calf rennet were superior in terms of chemical composition compared to the cheese in which lactic acid and papaya latex was used as coagulant (p=0.000-0.047). But the calcium concentration was found maximum in papaya latex cheese. Acidity was found highest in lactic acid cheese and papaya latex cheese had the highest pH value. On the other hand, standard plate count and coliform count was found highest in cheese coagulated by lactic acid, where microbial rennet cheese had the lowest count, and the microbial count of other two cheese was intermediate of them (p=0.000-0.001). Overall, microbial rennet, lactic acid, papaya latex, and abomasum rennet could be used to make cheese successfully, however, with a preference to microbial rennet.
 Bang. J. Anim. Sci. 2021. 50 (2): 73-79

The Interactions among Isolates of Lactiplantibacillus plantarum and Dairy Yeast Contaminants: Towards Biocontrol Applications

Yeast diversity in the cheese manufacturing process and in the cheeses themselves includes indispensable species for the production of specific cheeses and undesired species that cause cheese defects and spoilage. The control of yeast contaminants is problematic due to limitations in sanitation methods and chemicals used in the food industry. The utilisation of lactic acid bacteria and their antifungal products is intensively studied. Lactiplantibacillus plantarum is one of the most frequently studied species producing a wide spectrum of bioactive by-products. In the present study, twenty strains of L. plantarum from four sources were tested against 25 species of yeast isolated from cheeses, brines, and dairy environments. The functional traits of L. plantarum strains, such as the presence of class 2a bacteriocin and chitinase genes and in vitro production of organic acids, were evaluated. The extracellular production of bioactive peptides and proteins was tested using proteomic methods. Antifungal activity against yeast was screened using in vitro tests. Testing of antifungal activity on artificial media and reconstituted milk showed significant variability within the strains of L. plantarum and its group of origin. Strains from sourdoughs (CCDM 3018, K19-3) and raw cheese (L12, L24, L32) strongly inhibited the highest number of yeast strains on medium with reconstituted milk. These strains showed a consistent spectrum of genes belonging to class 2a bacteriocins, the gene of chitinase and its extracellular product 9 LACO Chitin-binding protein. Strain CCDM 3018 with the spectrum of class 2a bacteriocin gene, chitinase and significant production of lactic acid in all media performed significant antifungal effects in artificial and reconstituted milk-based media.

Integrating process modelling and sustainability assessment to improve the environmental and economic sustainability in the cheese industry

This paper combines process design and modelling with life cycle sustainability assessment to identify opportunities for improving the environmental and economic performance in the cheese industry. Considering both the production and consumption perspectives, the study considers first a range of improvement options in the cheese manufacturing process, followed by an assessment of the rest of the life cycle. For the manufacturing process, the focus is on energy efficiency and valorisation of waste with the following four options considered: Option 1 is a base case that reflects current manufacturing practice and therefore excludes energy recovery and waste utilisation; Option 2 includes heat integration applied to recover waste heat from the process; Option 3 considers the combination of heat integration with treatment of cheese whey via anaerobic digestion to produce biogas; in Option 4, heat integration is combined with treatment of whey via fermentation to produce bioethanol and animal feed. Cheddar cheese has been selected by way of example as one of the most consumed types of cheese in different countries, including the US and the UK. Using life cycle assessment and life cycle costing, the environmental and economic sustainability of cheese have been assessed for these options from farm gate to cheese-plant gate for the production perspective, and from cradle to grave for the consumption perspective. Option 4 is found to be the best alternative across all impacts and costs for both perspectives. For example, compared to the base case, the climate change impact and life cycle costs of cheese are reduced respectively by 148% and 158% for the production perspective, and by 3.4% and 8% for the consumption perspective. These reductions are mainly due to the co-production of bioethanol and animal feed. Production of biogas from whey in Option 3 has higher environmental impacts than the base case, making it the worst alternative. Taking the consumption of cheese at the UK level as an example, improvements in the manufacturing process via Option 4 could reduce the annual climate change impact of the food sector by around 209 kt CO 2 eq./yr and primary energy demand by 6.7 PJ/yr, while increasing the value added of cheese by up to 11%. These results will be of interest to cheese producers, food manufacturers, consumers and policy makers.

Comprehensive Utilization of Electro-Activated Whey-Based Media in the Cell Growth, Metabolites Production and Aroma Compounds Synthesis Using a Starter Culture Originated from Kefir Grain

Whey and whey permeate (WP) are the main by-products from cheese or casein manufacturing process and there is a serious demand of developing a sustainable approach for their utilization to evade environmental pollution. The objective of this study was to explore the feasibility of using electro-activated (EA) whey-based substrates (whey, WP, lactose) as carbon sources to produce valuable metabolites including organic acids (i.e., lactic, acetic, citric, and propionic acids), exopolysaccharides (kefiran), and volatile flavour compounds using the whole kefir grains as a starter culture. Fermentation was performed by inoculating a mixed microbiota from kefir grains in EA and non-EA solutions of lactose, whey, and WP and were statically incubated for 96 h at 30 ℃. The results showed that the EA substrates achieved a higher biomass growth in a reduced fermentation time than their non-EA mediums. The highest cell growth (6.04 g/L) was obtained for EA-whey after 72 h which was even 1.7-fold higher than a standard nutrition broth, the reinforced clostridial medium (RCM). Furthermore, EA-whey produced a maximum of 8.46, 3.97, 0.60, and 1.02 g/L of lactic, acetic, citric, and propionic acid, respectively. Moreover, EA-whey achieved the highest kefiran production of 2.99 g/L, followed by the whey (2.67 g/L), EA-WP (2.31 g/L), WP (1.88 g/L), RCM broth (1.42 g/L), EA-lactose (1.37 g/L), and lactose (0.91 g/L). The results also demonstrated that various aromatic volatile compounds were produced during the fermentation of EA-whey, which may increase the organoleptic characteristic/sensory quality of the fermented products. Thus, the results of the present study provide a strong evidence that the EA-substrates, especially EA-whey, could be potential feedstock to develop an efficient bioprocess for producing valuable metabolites using kefir grains as a suitable starter.

Dietary Whey Protein Supplementation Increases Immunoglobulin G Production by Affecting Helper T Cell Populations after Antigen Exposure.

Whey protein is a by-product of cheese and casein manufacturing processes. It contains highly bioactive molecules, such as epidermal growth factor, colony-stimulating factor, transforming growth factor-α and -β, insulin-like growth factor, and fibroblast growth factor. Effects of whey protein on immune responses after antigen (hemagglutinin peptide) injection were evaluated in rats. Experimental diets were formulated based on NIH-31M and supplemented with 1% amino acids mixture (CON) or 1% whey protein concentrate (WPC) to generate isocaloric and isonitrogenous diets. Rats were fed the experimental diets for two weeks and then exposed to antigen two times (Days 0 and 14). Blood was collected on Days 0, 7, 14, and 21 for hematological analysis. The WPC group showed decreased IgA and cytotoxic T cells before the antigen injection (Day 0) but increased IgG, IL-2, and IL-4 after antigen injection due to increased B cells and T cells. Helper T cells were increased at Days 14 and 21, but cytotoxic T cells were not affected by WPC. WPC may activate adaptive immunity (IgG) against antigen by modulating helper T cells. Bioactive molecules might contribute to the immune-enhancing effects of whey protein concentrate.

Bacterial Succession through the Artisanal Process and Seasonal Effects Defining Bacterial Communities of Raw-Milk Adobera Cheese Revealed by High Throughput DNA Sequencing.

The bacterial community of the artisanal Adobera cheese from Los Altos de Jalisco was described through high-throughput sequencing of 16S rRNA gene libraries. Samples were collected in two different seasons (dry and rainy) during four key steps of the manufacturing process (raw milk, fresh curd, matured curd, and cheese). Bacterial diversity was higher in early steps in comparison with the final elaboration stages. Firmicutes and Proteobacteria were the most abundant phyla, strongly represented by the Streptococcaceae, Enterobacteriaceae and Lactobacillaceae families, and core bacteria genera such as Streptococcus spp., Lactococcus spp., and Lactobacillus spp. Undesirable bacteria, including Pseudomonas spp. and Acinetobacter spp., were also detected in raw milk but almost undetectable at the end of the cheese manufacturing process, and seemed to be displaced by lactic-acid bacteria-related genera. Seasonal effects were observed on the community structure but did not define the core microbiota composition. Predictive metabolism was related to membrane transport, and amino-acid, lipid, and carbohydrate metabolism pathways. Our results contribute to deduce the role of bacteria involved in Adobera cheese manufacturing in terms of the metabolism involved, cheese microbial safety, and how undesirable bacterial populations could be regulated by process standardization as a potential tool to improve safety.

Effect of Pomegranate Juice on the Manufacturing Process and Characterization of Feta-Type Cheese during Storage

The present research aimed to produce Fruit Feta-type cheese and investigate the effects of pomegranate juice on the manufacturing process and characterization of Feta-type cheese during storage. In order to produce Feta-type cheese with pomegranate juice, part of the milk was replaced with pomegranate juice. Therefore, it was necessary to produce Feta-type cheese with whey-less method, which is a good substitute for ultrafiltrated cheese. Initially, whey-less Feta-type cheese was produced. The formula was optimized based on the physicochemical characteristics of the marketed ultrafiltrated Feta cheeses. At the optimal point, the amount of cream, MPC, WPC, and fresh milk were 45.6, 11.7, 2.7, and 40%, respectively. Whey-less Feta-type cheese with these ratios was produced and the effects of different levels of pomegranate juice (0, 5, 10, 15, and 20%) on its physicochemical, textural, microbial, and sensorial properties during 60 days of storage were studied. The results showed that pomegranate juice increased acidity, total phenol, anthocyanin, DPPH inhibition, and a ∗ value, and reduced the pH, peroxide value, thiobarbituric acid (TBA), proteolysis, lipolysis, and L ∗ and b ∗ values. Adding pomegranate juice to cheese reduced all of the textural indices except the adhesiveness. Sensory evaluation of the samples showed that the sample containing 20% of pomegranate juice had a higher score and was selected as the best sample.

Physicochemical and Microbiological Characterization of Protected Designation of Origin Ezine Cheese: Assessment of Non-starter Lactic Acid Bacterial Diversity with Antimicrobial Activity.

Ezine cheese is a non-starter and long-ripened cheese produced in the Mount of Ida region of Çanakkale, Turkey, with a protected designation of origin status. Non-starter lactic acid bacteria (NSLAB) have a substantial effect on the quality and final sensorial characteristics of long-ripened cheeses. The dominance of NSLAB can be attributed to their high tolerance to the hostile environment in cheese during ripening relative to many other microbial groups and to its ability to inhibit undesired microorganisms. These qualities promote the microbiological stability of long-ripened cheeses. In this study, 144 samples were collected from three dairies during the ripening period of Ezine cheese. Physicochemical composition and NSLAB identification analyses were performed using both conventional and molecular methods. According to the results of a 16S rRNA gene sequence analysis, 13 different species belonging to seven genera were identified. Enterococcus faecium (38.42%) and E. faecalis (18.94%) were dominant species during the cheese manufacturing process, surviving 12 months of ripening together with Lactobacillus paracasei (13.68%) and Lb. plantarum (11.05%). The results indicate that NSLAB contributes to the microbiological stability of Ezine cheese over 12 months of ripening. The isolation of NSLAB with antimicrobial activity, potential bacteriocin producers, yielded defined collections of natural NSLAB isolates from Ezine cheese that can be used to generate specific starter cultures for the production of Ezine cheese (PDO).

Evaluation of Mycobacterium avium subsp. paratuberculosis survival during the manufacturing process of Italian raw milk hard cheeses (Parmigiano Reggiano and Grana Padano)

Mycobacterium avium subsp. paratuberculosis (MAP), the agent of paratuberculosis in ruminants, is suspected to be involved in the aetiology of some human diseases. Notably, the consumption of milk and dairy products is considered to be the main route of human exposure to MAP because of its ability to survive during pasteurization and manufacturing processes. The aim of this study was to investigate, through a microbiological challenge test, the survival of MAP during the manufacturing and ripening period of two Italian hard cheeses, Parmigiano Reggiano and Grana Padano, made from raw bovine milk. The challenge test was performed in two different phases: the creaming phase and the manufacturing phase.The creaming phase, which is the first step of cheese production, was reproduced in the laboratory employing raw cow's milk spiked with a MAP reference strain at a final concentration of 5.58 log10 CFU/mL. After the creaming at 18 °C and 27 °C for 12 h, a decrease of 0.80 log10 and 0.77 log10 was observed in partially skimmed milk, respectively.In the second phase, two batches of raw cow's milk (1000 L each) were inoculated with MAP reference and wild strains, respectively. Then, the entire manufacturing process for Parmigiano Reggiano and Grana Padano, both of Protective Designation of Origin (PDO), was reproduced in an experimental cheese factory, starting from a concentration in milk of 5.19 ± 0.01 and 5.28 ± 0.08 log10 CFU/mL of MAP reference and wild strains, respectively. Heating the curd at 53 °C for 20 min did not affect MAP survival, however a significant decrease (p < 0.05) in MAP viability was observed during the moulding phase and after salting in brine, regarding the wild strains and the reference strain, respectively. In addition, a significant decrease was observed during the ripening period, at which time the MAP concentration dropped below the limit of detection from the second and the third month of ripening, for the wild and reference strains, respectively.Taking into account the poor data availability about MAP survival in hard cheeses, this study may improve the knowledge regarding the effect of the cheese manufacturing process on the MAP dynamics, supporting also the safety of traditional raw milk hard cheeses.

Highly proteolytic bacteria from semi-ripened Chiapas cheese elicit angiotensin-I converting enzyme inhibition and antioxidant activity

Chiapas cream cheese (CCH) manufacturing process involves a long acid-enzymatic coagulation period of full-fat cow raw milk to achieve an acid and crumbly cheese. These sensorial aspects are related to lactic acid bacteria activity during ripening. Our main objective was to test the hypothesis that CCH contained highly proteolytic strains able to release bioactive compounds upon milk-protein hydrolysis. First, the proteolysis of CCH was evaluated considering the peptide and amino acid profiles of cheese samples collected from Veracruz (AVCH) and Tabasco (HTCH). The angiotensin-converting-enzyme (ACE) inhibitory activity in cheese water-soluble fractions was evaluated. Thereafter, strains from both CCH samples were isolated and selected based on their proteolytic capability, genetic fingerprint differentiation and growth conditions. Finally, a range of activities in vitro were tested in milk fractions fermented with selected strains. CCH showed ACE inhibitory activity: IC50 = 1.75–2.75 mg/mL. Interestingly, AVCH contains 0.78 g/kg of the antihypertensive γ-aminobutyric acid. Three highly proteolytic strains showed ACE and high antioxidant activities upon milk fermentation. In conclusion, CCH contain proteolytic strains able to release bioactive compounds from milk proteins and potentially useful to produce functional ingredients and foods.

Formation of alanine, α-aminobutyrate, acetate, and 2-butanol during cheese ripening by Pediococcus acidilactici FAM18098

There is limited information about the contribution of Pediococcus acidilactici, a nonstarter lactic acid bacteria, to cheese ripening and flavour development. Model Tilsit-type and Gruyère-type cheeses were produced using P. acidilactici FAM18098 as an adjunct. The adjunct did not influence the cheese manufacturing processes. The pediococcal log counts ranged from 7.0 to 8.0 cfu g−1 after 90 and 120 days of ripening. P. acidilactici produced ornithine, a result of arginine metabolism by the arginine deiminase pathway, and α-aminobutyrate and alanine while simultaneously metabolising serine and threonine. The analysis of the volatile compounds in the cheeses showed that higher acetate, 2-butanone, and 2-butanol levels and lower diacetyl levels were present in the cheeses produced with P. acidilactici than in the control cheeses. The study illustrates that P. acidilactici can influence amino acid metabolism in cheese; further, ornithine, α-aminobutyrate, and acetate can serve as indicators for the presence of this species.

Sensoproteomics: A New Approach for the Identification of Taste-Active Peptides in Fermented Foods.

Aiming at the identification of the key bitter peptides in fermented foods, a new approach, coined "sensoproteomics", was developed and applied to fresh cheese samples differing in bitter taste intensity. By means of MPLC fractionation of the water-soluble cheese extracts in combination with taste dilution analysis, complex fractions with intense bitter taste were located and then screened by UPLC-MS/MS for the entire repertoire of ∼1600 candidate peptides, extracted from a literature meta-analysis on dairy products, by using a total of 120 selected reaction monitoring methods computed in silico. A total of 340 out of the 1600 peptides were found in the cheese samples, among which 17 peptides were identified as candidate bitter peptides by considering only peptides that were located in the bitter-tasting MPLC fractions (signal-to-noise ratio: ≥10) with a fold-change of ≥3 when comparing the less bitter to the more bitter cheese sample and that were validated by comparison with the synthetic reference peptides. While EIVPNS[phos]VEQK (αs1-CN70-78) and INTIASGEPT (κ-CN122-131) did not exhibit any bitter taste up to 2000 μmol/L, 15 of the 17 target peptides showed bitter taste thresholds ranging from 30 (ARHPHPHLSFM, κ-CN96-106) to 690 μmol/L (IQKEDVPS, αs1-CN81-88). Finally, quantitative peptide analysis followed by calculation of dose-overthreshold factors revealed a primary contribution of MAPKHKEMPFPKYPVEPF (β-CN102-119) and ARHPHPHLSFM (κ-CN96-106) to the perceived bitter taste of the fresh cheese samples. Finally, the evolution of the bitter peptides throughout two different fresh cheese manufacturing processes was quantitatively recorded.

Profiling of bacterial and fungal communities of Mexican cheeses by high throughput DNA sequencing

Cheese is a live food whose preparation involves procedures and microbial communities playing an important role for the final product. We characterized the bacterial and fungal diversity of seventeen different Mexican cheeses by high-throughput DNA sequencing of 16S/18S rDNA libraries. We propose the existence of bacterial and fungal core communities, where at genera level, bacteria include Streptococcus spp., Lactococcus spp., Lactobacillus spp., Aerococcus spp., and Weisella spp. while at species level, the fungal community includes Galactomyces reessii, Scheffersomyces stipitis, Saccharomyces cerevisiae (baker's yeast), and S. cerevisiae_rm11-1a. In addition to the bacterial and fungal core communities, we found members of the cheese microbiota that could be associated to other factors of the cheese manufacturing process. Co-occurrence analysis made in this work, indicates that bacterial and fungal communities maintain positive and negative interactions which are important to shape the resident microbial communities in cheeses. This work is a contribution to the description of the microbial diversity found in some Mexican cheeses.

Complete genomic sequences of Propionibacterium freudenreichii phages from Swiss cheese reveal greater diversity than Cutibacterium (formerly Propionibacterium) acnes phages

BackgroundA remarkable exception to the large genetic diversity often observed for bacteriophages infecting a specific bacterial host was found for the Cutibacterium acnes (formerly Propionibacterium acnes) phages, which are highly homogeneous. Phages infecting the related species, which is also a member of the Propionibacteriaceae family, Propionibacterium freudenreichii, a bacterium used in production of Swiss-type cheeses, have also been described and are common contaminants of the cheese manufacturing process. However, little is known about their genetic composition and diversity.ResultsWe obtained seven independently isolated bacteriophages that infect P. freudenreichii from Swiss-type cheese samples, and determined their complete genome sequences. These data revealed that all seven phage isolates are of similar genomic length and GC% content, but their genomes are highly diverse, including genes encoding the capsid, tape measure, and tail proteins. In contrast to C. acnes phages, all P. freudenreichii phage genomes encode a putative integrase protein, suggesting they are capable of lysogenic growth. This is supported by the finding of related prophages in some P. freudenreichii strains. The seven phages could further be distinguished as belonging to two distinct genomic types, or ‘clusters’, based on nucleotide sequences, and host range analyses conducted on a collection of P. freudenreichii strains show a higher degree of host specificity than is observed for the C. acnes phages.ConclusionsOverall, our data demonstrate P. freudenreichii bacteriophages are distinct from C. acnes phages, as evidenced by their higher genetic diversity, potential for lysogenic growth, and more restricted host ranges. This suggests substantial differences in the evolution of these related species from the Propionibacteriaceae family and their phages, which is potentially related to their distinct environmental niches.

Cheese Manufacturing and Bioactive Substance Separation: Separation and Preliminary Purification of cAMP from Whey.

Cheese consumption has been gradually increased in China. However, both the manufacturing process of cheese and the utilization of its main by-product were not well developed. Based on the sensory evaluation, Box-Behnken Design (BBD) was performed in the present study to optimize the cheese processing, which was proved more suitable for Chinese. The optimal parameters were: rennet 0.052 g/L, start culture 0.025 g/L and CaCl2 0.1 g/L. The composition analysis of fresh bovine milk and whey showed that whey contained most of the soluble nutrients of milk, which indicated that whey was a potential resource of cyclic adenosine-3’, 5’-monophosphate (cAMP). Thus, the cAMP was isolated from whey, the results of high-performance liquid chromatography (HPLC) analysis showed that the macroporous adsorption resins (MAR) D290 could increase the concentration of cAMP from 0.058 µmol/mL to 0.095 µmol/mL. We firstly purified the cAMP from the whey, which could become a new source of cAMP.