Biochemical characteristics of ewe and goat milk: Effect on the quality of dairy products

Identification of Potential Bioactive Peptides in Sheep Milk Kefir through Peptidomic Analysis at Different Fermentation Times

Sheep farming is an important socioeconomic activity in most Mediterranean countries, particularly Spain, where it contributes added value to rural areas. Sheep milk is used in Spain mainly for making cheese, but it can be used also for making other dairy products, such as the lactic-alcoholic fermentation product known as kefir. Dairy products have health benefits because, among other reasons, they contain molecules with biological activity. In this work, we performed a proteomics strategy to identify the peptidome, i.e., the set of peptides contained in sheep milk kefir fermented for four different periods of time, aiming to understand changes in the pattern of digestion of milk proteins, as well as to identify potential bioactive peptides. In total, we identified 1942 peptides coming from 11 different proteins, and found that the unique peptides differed qualitatively among samples and their numbers increased along the fermentation time. These changes were supported by the increase in ethanol, lactic acid, and D-galactose concentrations, as well as proteolytic activity, as the fermentation progressed. By searching in databases, we found that 78 of the identified peptides, all belonging to caseins, had potential biological activity. Of these, 62 were not previously found in any milk kefir from other animal species. This is the first peptidomic study of sheep milk kefir comprising time-course comparison.

Phenotypic characteristic of Staphylococcus aureus from subclinical mastitis in Etawah-crossbreed goats in Yogyakarta, Indonesia

Background and Aim

Subclinical mastitis (SCM) in Etawah-grade (PE) goats in Yogyakarta, Indonesia, is commonly due to Staphylococcus aureus. At present, S. aureus from SCM in PE goats in Yogyakarta has not been characterized. Therefore, this study aimed to phenotypically characterize S. aureus, which has been isolated from SCM of PE goats.

Materials and Methods

A total of 314 lactating PE goats were collected from 60 PE goat farms (e.g., Sleman, Bantul, and Kulonprogo) located in parts of Yogyakarta with an average age of 3-4 years old, three of which showed SCM based on the California mastitis test (CMT). Subclinical mastitis is confirmed in PE goats if CMT shows ++ or +++. Furthermore, S. aureus was detected by biochemical assays. Staphylococcus aureus could determine hemolysin (Hae), coagulase (Coa), clumping factor (Cf), and antibiotic susceptibility. Hemolytic bacteria were detected by culturing on blood agar plate, and Cf was detected by slide agglutination. The production of Coa was detected by tube coagulation. Staphylococcus aureus susceptibility was determined by antimicrobial agar diffusion using a paper disc.

Results

Phenotypically characterized S. aureus from PE goats with SCM in Yogyakarta, Indonesia, Coa-, Cf-, and Hae- were found to be resistant to erythromycin (ERYTHRO), ampicillin (AMP), penicillin (PEN-G), and sulfamethoxazole (SULFA).

Conclusion

The phenotypic characteristic of S. aureus, which was obtained from SCM in PE goats in Yogyakarta, consists of Coa, and Cf-. S. aureus cannot perform hemolysis of red blood cells. This phenotypic characteristic can prevent and control SCM in PE goats. Several antibiotics such as ERYTHRO, AMP, PEN-G, and SULFA were no longer effective for treating SCM in PE goats because S. aureus has developed its resistance to these antibiotics.

The Effect of Alpha s1 Genotype on Some Physiological and Chemical Milk Characteristics in Garganica Goat

In the present study individual milk samples were collected from 80 Garganica goats and the population was genotyped for CSN1S1. Seven different alleles were observed with the A allele found as predominant, followed by the F and B allele, and 14 different genotypes were observed. A proteomic approach was used to classify the individual milk on the basis of protein abundance: four levels of αs1-casein (CN) expression were identified as high (HAS-1), intermediate (IAS-1), low (LAS-1), and null (NAS-1). The present paper aimed to investigate the influence of the level of expression of αs1-casein fraction in milk on proteolytic activities, chemical composition, and renneting properties of individual Garganica goat milk. Results from the present study evidenced that the level of expression of αs1-casein fraction in Garganica goat milk affected chemical composition, curd firmness, and indigenous proteolytic enzymes. In particular, fat, protein, and casein content were higher in HAS-1 and IAS-1 compared to LAS-1 and NAS-1. The SCC decreased passing from the HAS-1 to the NAS-1 and the curd firmness displayed the highest value in HAS-1. The activity of plasmin (PL) was higher in HAS-1 and IAS-1 groups compared to the LAS-1 and NAS-1; whereas, PL plasminogen-derived (PG) activity was the highest in NAS-1 group. On the contrary, the activity of elastase was the highest in LAS-1, intermediate in the IAS-1 group, and the lowest in HAS-1 and NAS-1 groups. Present data demonstrated that the level of synthesis of αs1-CN reflects the efficiency of the mammary gland in the activation of the cellular mechanisms and influences the proteolytic activity in milk, especially the PL-PG system.

Coagulation process in Manchega sheep milk from Spain: A path analysis approach

Characteristics of sheep milk are of great interest for the dairy industry, as almost the totality of production is intended for cheesemaking. However, the existing relationships between these variables are complex. This study assessed composition, hygienic quality, coagulation properties, and curd yield of 1,200 individual Manchega sheep milk samples. The aim was to compare the effect of composition and hygienic quality on coagulation and curdling, and to evaluate the relationship between curd yields and the coagulation process and the effect of other features by using path analysis methodologies. Outcomes proved path analysis to be a useful and effective tool to assess these relationships through direct and indirect paths within the same model. Results showed that the factors that had a direct influence on milk coagulation were lactose concentration, casein content, and initial pH of milk. Contrastingly, somatic cells did not seem to have any effect (direct or indirect) on the coagulation process. Factors that directly affected curd yield were fat content, lactose concentration, casein content, and curd moisture. However, technological parameters showed little effect over curd yield.

Effect of the Ripening Period and Intravarietal Comparison on Chemical, Textural and Sensorial Characteristics of Palmero (PDO) Goat Cheese

Palmero cheese is an artisanal dairy product from the Canary Islands (Spain), awarded with the Protected Denomination of Origin (PDO) from the European Union. It is made with raw milk from the Palmera dairy goat on La Palma island. The aim of this research covered the physicochemical and sensorial characterization of Palmero cheese along 90 days of ripening. Palmero cheeses from four cheese factories were analysed for basic physicochemical parameters, instrumental texture and colour and sensorial profile. Most of the basic composition and the texture and colour attributes of Palmero cheese changed significantly along maturation. During the 90 days of ripening an increase in hardness, fracturability and gumminess (p < 0.001) occurred while elasticity decreased simultaneously (p < 0.001). The internal lightness value decreased significantly (p < 0.001), while yellowness increased (p < 0.001) during cheese ripening. Ripening time affected six of nine sensorial texture characteristics and the entire odour and flavour parameters analysed (p < 0.001). Regarding to intravarietal comparison, in general, cheeses from the four dairy plants showed similar composition although significant differences were detected on textural, colour and sensorial characteristics.

Biochemical, Physicochemical and Sensory Properties of Yoghurts Made from Mixing Milks of Different Mammalian Species

Among developed countries, bovine milk production makes a major contribution towards the economy. Elevating consumer demand for functional foods has triggered a niche for non-bovine milk-based products. Mixing milks from different species can be a strategy to increase the consumption of non-bovine milk and enable consumers and dairy companies to benefit from their nutritional and technological advantages. Thus, this review aimed to gather the most important research on yoghurts derived from processing mixtures of milks of different species. We discuss the impact of milk mixtures (i.e., species and milk ratio) on nutritional, physicochemical, sensory, rheological and microbiological properties of yoghurts. More specifically, this paper only highlights studies that have provided a clear comparison between yoghurts processed from a mixture of two milk species and yoghurts processed from a single species of milk. Finally, certain limitations and future trends are discussed, and some recommendations are suggested for future research.

The Impact of Mastitis on the Biochemical Parameters, Oxidative and Nitrosative Stress Markers in Goat's Milk: A Review

Goat mastitis has become one of the most frequently diagnosed conditions in goat farms, with significant economic impact on the dairy industry. Inflammation of the mammary gland poses serious consequences on milk composition, with changes regarding biochemical parameters and oxidative stress markers. The aim of this paper is to present the most recent knowledge on the main biochemical changes that occur in the mastitic milk, as well as the overall effect of the oxidative and nitrosative stress on milk components, focusing on both enzymatic and nonenzymatic antioxidant markers. Mastitis in goats is responsible for a decrease in milk production, change in protein content with pronounced casein hydrolysis, and reduction in lactose concentration and milk fat. Milk enzymatic activity also undergoes changes, regarding indigenous enzymes and those involved in milk synthesis. Furthermore, during mastitis, both the electrical conductivity and the milk somatic cell count are increased. Intramammary infections are associated with a reduced milk antioxidant capacity and changes in catalase, lactoperoxidase, glutathione peroxidase or superoxide dismutase activity, as well as reduced antioxidant vitamin content. Mastitis is also correlated with an increase in the concentration of nitric oxide, nitrite, nitrate and other oxidation compounds, leading to the occurrence of nitrosative stress.

Autogenic successions of bacteria and fungi in kefir grains from different origins when sub-cultured in goat milk

Kefir grains are a unique symbiotic association of different microbiota, including a variety of bacterial and fungal species. The microbiota in kefir grains is strongly influenced by the geographical origin and sub-culturing environment. After sub-culturing in goat milk for 2 to 4 months, amplicon sequencing (16S rRNA and ITS1 region) was applied for the identification of bacterial and fungal autogenic succession of three kefir grains collected from China (CN, Asia), Germany (DE, Europe) and United States of America (USA, America). Taxonomic analysis displayed three main bacterial and fungal species in kefir grains from different origins during sub-culturing process (Lactobacillus helveticus, Lactobacillus kefiranofaciens and Lactobacillus kefiri for bacteria, Kazachstania unispora, Kluyveromyces marxianus and Saccharomyces cerevisiae for fungi). Based on the results of beta diversity analysis, microbiota in kefir grains from CN and DE would be stable when sub-cultured in goat milk for more than three months. Differently, a highly microbial stability has been found for the sample from USA during the whole sub-culturing process. These results helped to understand the composition and stability of microbiota in kefir grains when sub-cultured in goat milk.

The Effect of Mixing Milk of Different Species on Chemical, Physicochemical, and Sensory Features of Cheeses: A Review

The yield and quality of cheese are associated with the composition, physicochemical, sensory, rheological, and microbiological properties of milk and with the technology applied to the milk before and/or during cheese processing. This review describes the most important research on cheeses obtained from processing mixtures of different milk species and discusses the effect of milk mixtures (i.e., species and mixture ratios) on composition, physicochemical, sensory, rheological, and microbiological properties of cheeses. More specifically, the present review paper will gather and focus only on studies that have provided a clear comparison between cheeses produced from a mixture of two milk species to cheeses produced from only one species.

Probiotics and prebiotics in non-bovine milk

Probiotics are live microorganisms that, when administered in adequate numbers, confer health benefit/s on the host, while prebiotics are nondigestible food ingredients that are selectively stimulate the growth of beneficial microorganisms in the distal parts of the host digestive tract conferring health benefits. Dairy products manufactured mainly using bovine milk is the major vehicle in delivering probiotics to humans. At present, there is an increasing demand for non-bovine probiotic milk products. Both bovine and non-bovine dairy products contain several ingredients with prebiotic properties such as oligosaccharides that could positively interact with probiotics to alter their functional properties. Furthermore, these bovine and non-bovine products could be fortified with prebiotics from various sources such as inulin and oligofructose in order to provide additional health benefits. In addition, non-bovine milk products are good sources for isolating novel potential probiotics. Non-bovine milk such as goat, sheep, camel and donkey have been used in producing several probiotic products including set-yoghurt, drinking-yoghurt, stirred-yoghurt, ice cream and cheese. Prebiotic inclusions in non-bovine milk at present is mainly associated with goat and sheep milk products. In this context, this chapter focuses on the different types of non-bovine milk products containing probiotics and prebiotics, and product quality and microbiological characteristics with special reference to probiotic viability.

Hydrolysis of casein from different sources by immobilized trypsin on biochar: Effect of immobilization method

The present study aimed to evaluate the effect of the immobilization method of trypsin on biochar on the hydrolysis of casein from different sources, when compared to the process using trypsin in native form, to obtain bioactive peptides. The modification of the surface of biochar with glutaraldehyde was effective, as shown by the results of FTIR assay and the texture profile of the materials. Both activated and functionalized biochar showed high immobilization efficiency (greater than 87%) and high binding capacity (greater than 91 mg/g). During hydrolysis, the biocatalyst obtained by enzyme immobilization on the functionalized biochar presented a higher hydrolysis capacity for the different caseins when compared to the enzyme immobilized by adsorption, with values of 3.05 and 2.73 U/mg for goat casein, 2.36 and 1.85 U/mg for bovine casein, and 2.60 and 2.37 U/mg for buffalo, casein, respectively, with 60 min of reaction. The results of inhibitory activity in this study ranged from 93.5% and 25.5% for trypsin in its free form and immobilized on functionalized activated carbon, respectively, under the same reaction conditions. The immobilization methods were efficient, presenting high immobilization capacity. The proteolytic activity of trypsin immobilized via covalent binding was higher when compared the immobilization by adsorption. Thus, the functionalized biochar has proven to be potential support for enzyme immobilization, and the biocatalyst can be reused for more than 4 cycles. Despite lower ACE inhibition values of hydrolyzed obtained with the immobilized enzymes compared to free enzymes, biocatalysts present advantage due to the possibility of reuse.

Effect of flaxseed (Linum usitatissimum) and soybean (Glycine max) oils in Egyptian lactating buffalo and cow diets on the milk and soft cheese quality

Produce and compare soft cheese with potential benefits of human health from Egyptian buffalo's and cow's milk was studied. Eight Egyptian lactating buffalos and cows were fed a total mixed ration supplemented with either 0% oil (CD), 2% flaxseed oil (DFO), 2% soybean oil (DSO), or 2% of their mixture (1:1, DFSO) according to a double 4 x 4 Latin Square design. Milk yield was similar between buffalo's diets but was higher in cows fed a DFO, DSO or DFSO resulting in 11.15, 8.21% or 8.97% increases compared with the control diet, respectively. Milk composition was not significantly affected in both buffalos and cows fed diets. The DFO, DSO or DFSO displayed decreased short-chain fatty acids, especially DSO and DFSO (3.73 and 3.33%, respectively) when compared to CD for buffalo milk (6.32%). The DSO and DFSO were  more effective for increasing unsaturated fatty acids followed by the DFSO in buffalo's milk fat (42.31 and 41.90 %), whereas DFO and DFSO were more effective in cow's milk fat (39.67 and 39.84%), respectively. DFO, DSO or DFSO had no significant effect on the yield, composition and sensory properties of resultant soft cheese compared to the CD for both lactating cows and buffalos. During storage, a diet rich in unsaturated fatty acids enhances protein proteolysis and antioxidant activity of soft cheese during storage compared to the CD especially for soft cheese produced from buffalo's milk.

Effect of Milk Type on the Microbiological, Physicochemical and Sensory Characteristics of Probiotic Fermented Milk

The production of fermented milk using cow milk, goat milk and a mixture of them (1:1) was evaluated. The traditional yogurt starter culture was used-Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus, along with Lactobacillus casei ATCC 393. The objective was to monitor the viability of these cultures during the storage of fermented milk at 4 °C for up to 28 days. Storage significantly affected the viability of all microorganisms and especially L. bulgaricus. All microorganisms retained viable numbers higher than 7.5 log CFU g-1, even after 4 weeks of storage, which is important to confirm the probiotic character of the product. The use of goat milk significantly affected the pH and acidity of fermented milk. More specifically, the use of goat milk led to fermented milk with lower pH values and higher acidities than fermented milk with cow milk. The sensory evaluation ascertained the overall quality of fermented milk with a mixture of cow and goat milk, which scored similar values to the commercial sample.

Effect of cold and frozen temperatures on artisanal goat cheese containing probiotic lactic acid bacteria isolates (Lactobacillus plantarum TW14 and Lactobacillus rhamnosus TW2)

Aim:

The research was conducted to determine the effect of temperature and storage duration on the physicochemical, lipolytic, microbiological, and proteolytic characteristics of goat cheese made using Lactobacillus plantarum TW14 and Lactobacillus rhamnosus TW2 bacteria.

Materials and Methods:

The cheese was stored at 4°C and −20°C for 0, 15, 30, 45, and 60 days. Observations were made on its physicochemical, lipolysis, and microbiological characteristics. The proteolysis pattern was measured with sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Results:

The protein, fat, ash and total solids levels of cold-stored cheese were higher than the frozen-stored one. The frozen-stored cheese’s free fatty acids (FFA) and acid degree value (ADV) levels are lower than those of the cold-stored cheese as indicated by the partial lipolysis event. The total yeast in the frozen-stored cheese is lower than that in the frozen-stored cheese. Finally, the electrophoresis profile indicates that proteolysis of the frozen-stored cheese is formed since there have been detected α_s1-casein, α_s2-casein, β-casein, and κ-casein in the casein breakdown during the 60-day storage.

Conclusion:

The physicochemical characteristics of cold-stored cheese are better than the cheese stored at frozen temperature. However, frozen-stored cheese produces lower FFA and ADV than cold-stored cheese and lipolysis occurs only partially.

Cardoon-based rennets for cheese production

The use of crude aqueous extracts of Cynara cardunculus flowers as coagulants in the production of high-quality sheep and goat cheeses-as are the cases of several Portuguese and Spanish cheese varieties with Protected Designation of Origin status-has been maintained since ancient times. The unique rheological attributes and sensory properties characteristic of these cheeses have always suggested that this plant coagulant (and, therefore, its isolated milk-clotting proteases) could be used as alternative rennet in the dairy industry, particularly suited for the production of sheep and goat cheeses. However, the lack of standardization of C. cardunculus crude flower extracts, whose quality and performance depends on numerous factors, has always hampered the application of this plant rennet in industrial production scales. To overcome these limitations, and to aim at developing more effective solutions with potential for scalability of production and commercial application, several strategies have been undertaken in more recent years to establish new cardoon-based rennets. This review provides an overview on these developments and on the currently available solutions, which range from producing standardized formulations of native cardoon enzymes, to the optimization of the heterologous production of cardosins and cyprosins to generate synthetic versions of these milk-clotting enzymes. Challenges and emerging opportunities are also discussed.

Effect of milk origin on proteolysis and accumulation of biogenic amine during ripening of Dutch-type cheese

Dairy products from goat's milk are characterized by their distinctive aroma and their specific taste. However, the strong aroma can discourage some consumers. Properties of cheese can be modified by the combination of goat's and cow's milk. On the other hand, chemical diversity from different milk origin may affect the changes during ripening. The aim of the study was to compare the intensity of changes during ripening of model cheese samples produced with various ratios of goat's and cow's milk. The combinations 100:0 (100% goat's milk), 75:25, 50:50, 25:75 and 0:100 (100% cow's milk) were used for the manufacture of Dutch-type cheeses, which were ripened during a period of 84 days. Protein profile, free amino acid content and biogenic amine content were used for the description of cheese properties during storage. Cluster analysis showed different changes in the protein matrix of the examined samples. The results indicated that even low addition of cow's milk significantly affected the protein profile. However, the homology of protein profiles rose with the increasing ripening time. More intensive proteolysis occured in the samples with predominance of goat's milk. Moreover, cheese samples produced only from goat's milk presented a significant increase inthe amount of free amino acids after 14 days of ripening. The effect of milk origin on the production of biogenic amines was also examined. However, higher concentrations of biogenic amines were detected in samples manufactured from goat's milk. Tyramine, putrescine, histamine and phenylethylamine were detected during the storage of the samples. The total biogenic amine content exceeded 100 mg/kg in samples with predominance of goat's milk.

Bioactive Peptides in Animal Food Products

Proteins of animal origin represent physiologically active components in the human diet; they exert a direct action or constitute a substrate for enzymatic hydrolysis upon food processing and consumption. Bioactive peptides may descend from the hydrolysis by digestive enzymes, enzymes endogenous to raw food materials, and enzymes from microorganisms added during food processing. Milk proteins have different polymorphisms for each dairy species that influence the amount and the biochemical characteristics (e.g., amino acid chain, phosphorylation, and glycosylation) of the protein. Milk from other species alternative to cow has been exploited for their role in children with cow milk allergy and in some infant pathologies, such as epilepsy, by monitoring the immune status. Different mechanisms concur for bioactive peptides generation from meat and meat products, and their functionality and application as functional ingredients have proven effects on consumer health. Animal food proteins are currently the main source of a range of biologically-active peptides which have gained special interest because they may also influence numerous physiological responses in the organism. The addition of probiotics to animal food products represent a strategy for the increase of molecules with health and functional properties.

Milk from different species: Relationship between protein fractions and inflammatory response in infants affected by generalized epilepsy

The present study was undertaken to evaluate the effect of protein fractions from bovine, caprine, and ovine milk on production of cytokines and reactive oxygen species (ROS) and reactive nitrogen species (RNS) by cultured peripheral blood mononuclear cells (PMBC) from infants with generalized epilepsy. Bovine, caprine, and ovine bulk milks were pasteurized and analyzed for chemical composition. Then, PBMC were isolated from 10 patients with generalized epilepsy (5 males; mean age 33.6±5.4mo). Production of tumor necrosis factor-α (TNF-α), IL-10, IL-6, and IL-1β was studied in cultured PBMC (from infants with epilepsy and controls) stimulated by bovine, caprine, and ovine milk and casein and whey protein fractions, and levels of ROS and RNS were measured in the culture supernatant. The ability of PBMC to secrete cytokines in response to milk and protein fraction stimulation may predict the secretion of soluble factor TNF-α in the bloodstream of challenged patients. Bovine, caprine, and ovine bulk milks induced low-level production of IL-10 by cultured PBMC in at least 50% of cases; the same behavior was observed in both casein and whey protein fractions for all species studied. Bovine and ovine milk and their casein fractions induced production of lower levels of IL-1β in 80% of patients, whereas caprine milk and its casein fraction induced the highest levels in 80% of patients. The amount of IL-6 detected after stimulation of PBMC by milk and its fractions for all species was lower than that of other proinflammatory cytokines. In the bovine, total free radicals were higher in bulk milk and lower in the casein fraction, whereas the whey protein fraction showed an intermediate level; in caprine, ROS/RNS levels were not different among milk fractions, whereas ovine had higher levels for bulk milk and casein than the whey protein fraction. Lower levels of ROS/RNS detected in PBMC cultured with caprine milk fraction could be responsible for the lower levels of TNF-α cytokine in the corresponding fraction. Cytokines might be useful biomarkers to discriminate the effects of foods on the inflammatory response; dietary strategies could help in alleviating the negative effects of epilepsy in infants.

Influence of lactation stage and some flock management practices on sensory characteristics of goat milk from Brazilian Saanen breed

This study evaluated the influence of lactation stage (early, middle, late) and management practices (milking hygiene and buck presence) on the sensory attributes of Saanen goat milk. Goats were randomly divided in four groups in respect of different milking sanitary procedures and the presence/absence of the buck in the barn. Milk samples were analyzed for sensory attributes including quantitative descriptive analysis (QDA) and acceptance. The milking hygiene practice caused no significant influence on microbiological parameters. Results of QDA revealed that the buck presence increased the characteristic odor of milk at the middle and late lactation stages. The off-odor and off-flavor descriptors showed a distinct response since a higher intensity of these sensory characteristics was noted in the samples obtained from goats maintained without the buck. Odor and flavor contributed most in characterizing the different samples regardless of the management practice and lactation stage. The acceptance of odor showed to be influenced only by the lactation stage, while the acceptance of flavor was only through the presence of the buck. Odor acceptance correlated negatively to off-odor and off-flavor, suggesting that these two sensory attributes impaired the preference for the aroma of the milk samples.

Activities of indigenous proteolytic enzymes in caprine milk of different somatic cell counts

Individual caprine milk with different somatic cell counts (SCC) were studied with the aim of investigating the percentage distribution of leukocyte cell types and the activities of indigenous proteolytic enzymes; proteolysis of casein was also studied in relation to cell type following recovery from milk. The experiment was conducted on 5 intensively managed dairy flocks of Garganica goats; on the basis of SCC, the experimental groups were denoted low (L-SCC; <700,000 cells/mL), medium (M-SCC; from 701,000 to 1,500,000 cells/mL), and high (H-SCC; >1,501,000 cells/mL) SCC. Leukocyte distribution differed between groups; polymorphonuclear neutrophilic leukocytes were higher in M-SCC and H-SCC milk samples, the percentage macrophages was the highest in H-SCC, and levels of nonviable cells significantly decreased with increasing SCC. Activities of all the main proteolytic enzymes were affected by SCC; plasmin activity was the highest in H-SCC milk and the lowest in L-SCC, and elastase and cathepsin D activities were the highest in M-SCC. Somatic cell count influenced casein hydrolysis patterns, with less intact α- and β-casein in H-SCC milk. Higher levels of low electrophoretic mobility peptides were detected in sodium caseinate incubated with leukocytes isolated from L-SCC milk, independent of cell type, whereas among cells recovered from M-SCC milk, macrophages yielded the highest levels of low electrophoretic mobility peptides from sodium caseinate. The level of high electrophoretic mobility peptides was higher in sodium caseinate incubated with polymorphonuclear neutrophilic leukocytes and macrophages isolated from M-SCC, whereas the same fraction of peptides was always the highest, independent of leukocyte type, for cells recovered from H-SCC milk. In caprine milk, a level of 700,000 cells/mL represented the threshold for changes in leukocyte distribution, which is presumably related to the immune status of the mammary gland. Differences in the profile of indigenous lysosomal proteolytic enzymes in caprine milk may influence the integrity of casein based on proteolysis patterns of sodium caseinate incubated with isolated and lysed leukocyte types.

Influence of pig rennet on fatty acid composition, volatile molecule profile, texture and sensory properties of Pecorino di Farindola cheese

BACKGROUND

Pig rennet is traditionally used in Pecorino di Farindola cheese. In this study, different Pecorino cheeses obtained using calf, kid and pig rennets were compared in terms of fatty acids, volatile molecule profile, texture and sensory properties during ripening.

RESULTS

The rennet type influenced the fatty acid composition of cheeses, though palmitic, myristic and oleic acids were always predominant. The analysis of volatiles by SPME-GC/MS showed that Pecorino from calf rennet, at the end of ripening, was the least 'evolved' in terms of volatile profile. SPME-GC/MS analysis revealed that cheeses from calf rennet showed the slowest accumulation of free fatty acids over ripening time. Volatile data permitted the differentiation of cheese samples ripened from 30 to 180 days according to the rennet used. Texture analysis differentiated cheeses made with pig and calf rennet from those made with kid rennet, which were less hard and more elastic than the former. Also sensory analysis differentiated cheese samples on the basis of rennet type, and cheeses made with pig rennet showed the lowest elasticity, bitter taste and fruity and hay flavour intensities.

CONCLUSION

Pig rennet is fundamental to determine the quality parameters of Pecorino di Farindola cheese and could be used to impart peculiar quality features to ewe's milk cheeses.