Proteomic study of proteolysis during ripening of Cheddar cheese made from milk over a lactation cycle

Graduate Student Literature Review: Current understanding of the influence of on-farm factors on bovine raw milk and its suitability for cheesemaking

Relationships between dairy farm practices, the composition and properties of raw milk, and the quality of the resulting cheese are complex. In this review, we assess the effect of farm factors on the quality of bovine raw milk intended for cheesemaking. The literature reports several prominent farm-related factors that are closely associated with milk quality characteristics. We describe their effects on the composition and technological properties of raw milk and on the quality of the resulting cheese. Cow breed, composite genotype, and protein polymorphism all have noticeable effects on milk coagulation, cheese yield, and cheese composition. Feed and feeding strategy, dietary supplementation, housing and milking system, and seasonality of milk production also influence the composition and properties of raw milk, and the resulting cheese. The microbiota in raw milk is influenced by on-farm factors and by the production environment, and may influence the technological properties of the milk and the sensory profile of certain cheese types. Advances in research dealing with the technological properties of raw milk have undoubtedly improved understanding of how on-farm factors affect milk quality attributes, and have refuted the concept of one milk for all purposes. The specific conditions for milk production should be considered when the milk is intended for the production of cheese with unique characteristics. The scientific identification of these conditions would improve the current understanding of the complex associations between raw milk quality and farm and management factors. Future research that considers dairy landscapes within broader perspectives and develops multidimensional approaches to control the quality of raw milk intended for long-ripening cheese production is recommended.

Changes in the chemical and in-vitro antihypertensive properties of sweet whey obtained from miniature fresh, Chanco and Gouda-style model cheeses

This Technical Research Communication evaluated the influence of various cheese manufacture methods on the composition and in vitro antihypertensive activity of sweet whey samples obtained from miniature models for fresh, Chanco and Gouda-style cheese processing using bulk-tank milks throughout a year. Raw milks from morning milking were standardized, pasteurized and used to obtain sweet whey using cheesemaking protocols for each variety on 200 g scale, as well the use of whey dilution at levels of 0, 15, 30 and 45% in Chanco and Gouda-style making. The composition of sweet whey obtained within each cheesemaking variety was similar among different timepoints of the year (P > 0.05), which was attributed to similar composition of milks and the use standardized cheesemaking protocols used for this study. As expected, the use of whey dilution led to sweet whey samples with reduced levels of total solids (P < 0.05), but they exhibited an improvement of the in vitro antihypertensive properties, which may be attributed to the formation of low-molecular weight bioactive peptides due to increased cheese making times. The results of this study suggest that modifying cheese manufacture protocols may have a direct impact on the bioactive properties of sweet whey. Future work will be required to identify and evaluate the feasibility to purify bioactive peptides obtained from sweet whey.

Characterization of Bacterial Communities in Mexican Artisanal Raw Milk "Bola de Ocosingo" Cheese by High-Throughput Sequencing

The dynamics of bacteria community of "Bola de Ocosingo" cheese, a Mexican artisanal raw milk cheese was investigated by high-throughput sequencing (454 pyrosequencing). Dairy samples (raw milk, curd, cheese at 50 and 110 days of ripening) were collected at dry (March-June) and rainy season (August-November) from three producers located in Chiapas, Mexico. In general, raw milk contained high bacterial diversity which was reduced throughout cheese manufacture. However, in two productions an important increase during cheese ripening was observed probably due to cross-contamination. Species such as Streptococcus thermophilus, Lactococcus lactis, Lactobacillus helveticus, L. delbrueckii and L. plantarum from which potential probiotic strains may be obtained, predominated during processing, varying its prevalence from one producer to another. Furthermore, low proportions of Escherichia coli/Shigella flexnerii were detected in almost all processes, however, could not be recovered by traditional methodology, indicating presence of non-cultivable cells. This work provides insights into bacteria communities of Bola de Ocosingo cheese for starter culture development, many of which are reported to provide health related benefits, and the usefulness of high-throughput sequencing to evidence cross-contamination during processing.

Proteomics in food: Quality, safety, microbes, and allergens

Food safety and quality and their associated risks pose a major concern worldwide regarding not only the relative economical losses but also the potential danger to consumer's health. Customer's confidence in the integrity of the food supply could be hampered by inappropriate food safety measures. A lack of measures and reliable assays to evaluate and maintain a good control of food characteristics may affect the food industry economy and shatter consumer confidence. It is imperative to create and to establish fast and reliable analytical methods that allow a good and rapid analysis of food products during the whole food chain. Proteomics can represent a powerful tool to address this issue, due to its proven excellent quantitative and qualitative drawbacks in protein analysis. This review illustrates the applications of proteomics in the past few years in food science focusing on food of animal origin with some brief hints on other types. Aim of this review is to highlight the importance of this science as a valuable tool to assess food quality and safety. Emphasis is also posed in food processing, allergies, and possible contaminants like bacteria, fungi, and other pathogens.

Animal board invited review: advances in proteomics for animal and food sciences

Animal production and health (APH) is an important sector in the world economy, representing a large proportion of the budget of all member states in the European Union and in other continents. APH is a highly competitive sector with a strong emphasis on innovation and, albeit with country to country variations, on scientific research. Proteomics (the study of all proteins present in a given tissue or fluid - i.e. the proteome) has an enormous potential when applied to APH. Nevertheless, for a variety of reasons and in contrast to disciplines such as plant sciences or human biomedicine, such potential is only now being tapped. To counter such limited usage, 6 years ago we created a consortium dedicated to the applications of Proteomics to APH, specifically in the form of a Cooperation in Science and Technology (COST) Action, termed FA1002--Proteomics in Farm Animals: www.cost-faproteomics.org. In 4 years, the consortium quickly enlarged to a total of 31 countries in Europe, as well as Israel, Argentina, Australia and New Zealand. This article has a triple purpose. First, we aim to provide clear examples on the applications and benefits of the use of proteomics in all aspects related to APH. Second, we provide insights and possibilities on the new trends and objectives for APH proteomics applications and technologies for the years to come. Finally, we provide an overview and balance of the major activities and accomplishments of the COST Action on Farm Animal Proteomics. These include activities such as the organization of seminars, workshops and major scientific conferences, organization of summer schools, financing Short-Term Scientific Missions (STSMs) and the generation of scientific literature. Overall, the Action has attained all of the proposed objectives and has made considerable difference by putting proteomics on the global map for animal and veterinary researchers in general and by contributing significantly to reduce the East-West and North-South gaps existing in the European farm animal research. Future activities of significance in the field of scientific research, involving members of the action, as well as others, will likely be established in the future.

Influence of the Probiotic Lactobacillus acidophilus NCFM and Lactobacillus rhamnosus HN001 on Proteolysis Patterns of Edam Cheese

The objective of this study is to determine the viability of Lactobacillus acidophilus NCFM and Lactobacillus rhamnosus HN001 in Edam cheese as well as the effect of probiotic bacteria on paracasein proteolysis and changes in the water activity during ripening. The use of probiotics L. rhamnosus HN001 and L. acidophilus NCFM in Edam cheese slightly changed its chemical composition, but the change was not significant. The pH values were significantly correlated with the changes in Lactobacillus count (R=-0.807) and the level of phosphotungstic acid-soluble nitrogen compounds in total nitrogen (PTA-SN/TN) (R=0.775). After 10 weeks of ripening, the highest level of trichloroacetic acid-soluble nitrogen compounds in total nitrogen (TCA-SN/TN) was observed in the cheese containing L. rhamnosus HN001 (11.87%) and slightly lower level in the cheese containing L. acidophilus NCFM (7.60%) and control cheese (6.24%). The highest level of PTA-SN/TN fraction was noted in cheese containing L. acidophilus NCFM (3.48%) but the lowest level was observed in control cheese (2.24%) after ten weeks of ripening. The changes in the levels of PTA-SN/TN (R=-0.813) and TCA-SN/TN (R=-0.717) fractions were significantly (p<0.05) correlated with the viability of probiotic counts. Water activity (aw ) strongly correlated with the PTA-SN/TN level (R=-0.824) and bacteria viability (R=-0.728). All of the analyzed cheeses were characterized by high counts of L. rhamnosus HN001 and L. acidophilus NCFM during ten weeks of ripening.

Bovine milk proteome: quantitative changes in normal milk exosomes, milk fat globule membranes and whey proteomes resulting from Staphylococcus aureus mastitis

Milk protein expression in healthy cows and cows with mastitis will provide information important for the dairy food industry and immune function in the mammary gland. To facilitate protein discovery, milk was fractioned into whey, milk fat globule membranes (MFGM) and exosomes from healthy and Staphylococcus aureus infected cows. Amine-reactive isobaric tags (iTRAQ) were used to quantify protein changes between milk fractions isolated from healthy and S. aureus infected cows. 2971 milk proteins were identified with a false discovery rate of 0.1%. Greater than 300 milk proteins associated with host defense were identified and 94 were significantly differentially regulated in S. aureus infected milk compared to their uninfected controls. These differentially regulated host defense proteins were selectively segregated in the 3 milk compartments examined. An example of this segregation of host defense proteins was the partitioning and high concentration of proteins indicative of neutrophil extracellular traps (NETs) formation in the MFGM preparations from S. aureus infected milk as compared to exosomes or whey. Protein composition changes found in milk exosomes, MFGM and whey during an infection provides new and comprehensive information on milk protein composition in general as well as changes occurring during an infection.

BIOLOGICAL SIGNIFICANCE

The significance of this study is the identification and quantification of the individual components of the neutrophil extracellular traps (NET) functional proteome in an apparent stable complex with MFGM and/or milk fat globules during an intra-mammary infection. NETs could be functionally relevant in intra-mammary infection, as it is known that during an infection neutrophils ingest large amounts of milk fat that down regulates many of their traditional immune functions. Thus the presence of NETs in milk fat provides new insights to mammary immune function and suggests a role for NETs in clinical mastitis. These in vivo NETs can now be tested to determine if they retain functional antimicrobial activity when primarily associated with milk fat. Then we can estimate their real world functional relevance during an intra-mammary infection, which is one key to understanding clinical mastitis in dairy cows.

Perspectives on the contribution of lactic acid bacteria to cheese flavor development

It has been known since the 1960s that lactic acid bacteria are essential for the development of cheese flavor. In the ensuing 50 years significant research has been directed at understanding the microbiology, genetics and biochemistry of this process. This review briefly covers the current status of cheese flavor development and then provides our vision for approaches which will enhance our understanding of this process. The long-term goal of this area of research is to enable technology (i.e. cultures and enzymes) that results in consistent rapid development of cheese variety-specific characteristic flavors.