Physicochemical Composition, Antioxidant Status, Fatty Acid Profile, and Volatile Compounds of Milk and Fresh and Ripened Ewes' Cheese from a Sustainable Part-Time Grazing System

Factors influencing conjugated linoleic acid content of dairy products: challenges and strategies

Conjugated linoleic acid (CLA), a bioactive fatty acid that provides various physiological benefits, has gained increasing attention in the food industry, and various studies have focused on enhancing its content in dairy products. The factors influencing CLA content in dairy products vary significantly, including lactation stage, breed type, seasonality, feed, management methods of the animals, the manufacturing processes, storage, and ripening periods of the product. Additionally, the incorporation of CLA-producing probiotic bacteria, such as Lactobacillus, Lactococcus, Bifidobacterium, and Propionibacterium, is an emerging study in this field. Studies have revealed that factors affecting the CLA content in milk affect that in dairy products as well. Furthermore, the species and strains of CLA-producing bacteria, fermentation conditions, ripening period, and type of dairy product are also contributing factors. However, production of CLA-enhanced dairy products using CLA-producing bacteria while maintaining their optimal viability and maximizing exposure to free linoleic acid remains limited. The current review emphasized the factors affecting the CLA content and related mechanisms, challenges in the application of CLA-producing probiotic bacteria, and strategies to address these challenges and enhance CLA production in dairy products. Therefore, the development of functional dairy products with enhanced CLA levels is expected to be possible.

Feeding Dairy Goats Dehydrated Orange Pulp Improves Cheese Antioxidant Content

Agroindustrial by-products constitute an alternative source of feed livestock, and their use contributes to the sustainability of livestock systems and the circular bioeconomy. The effects of replacing cereal (0%, 40%, and 80%) with dehydrated orange pulp (DOP) in the diet of goats on the antioxidant and fatty acid (FA) contents of cheeses were evaluated. For a more suitable understanding of the role of coagulant enzymes in establishing the properties of the cheese, the effect of milk-clotting with animal and vegetable rennet was also analysed. The rennet did not substantially affect the FA or the antioxidant compounds, and the use of DOP did not affect the FA contents. However, the α-tocopherol levels, total phenolic compounds (TPC), and total antioxidant capacity (TAC) in cheeses increased as the percentage of DOP replacing cereals increased. Moreover, the high correlation obtained between the TAC and the TPC (r = 0.73) and α-tocopherol (r = 0.62) contents indicated the important role played by these compounds in improving the antioxidant capacity of the cheese. In conclusion, DOP is a suitable alternative to cereals in the diet of goats and improves the antioxidant status of the cheese produced.

The effect of different management systems on milk yield and milk quality in Awassi sheep

This study aimed to evaluate the effect of concentrate-based feeding (CF) and artificial pasture-based grazing (APG) management systems on milk yield, fatty acids, nutritional indices, and milk physicochemical characteristics of Awassi ewes. The research involved 300 heads of Awassi ewes, which were divided into two groups. Awassi sheep were managed in a CF and APG system to test the milk yield characteristics. The results showed a significant ( P < 0.01 ) difference in milk yield and lactation length between CF and APG management systems of ewes. The average daily milk yield showed a nonsignificant difference for both management systems, and no significant changes ( P > 0.05 ) in the chemical composition of CF and APG management systems were observed. Palmitic (C16:0), myristic (C14:0), stearic (C18:0) capric (C10:0), and lauric (C12:0) acids were the major saturated fatty acids found in milk from both management systems. The level of linoleic acid (C18:2 n-6) was significantly different in both treatments ( P < 0.05 ), but the linolenic (C18:3 n-3) acid level was nonsignificant in milk from the CF and APG management systems. The hypocholesterolemic / hypercholesterolemic (h / H) fatty acid and thrombogenicity (TI) ratios were significantly different ( P < 0.05 ); however, the atherogenicity (AI) had no significant difference between confined and grazing systems. In conclusion, it can be said that the lactation length and lactation milk yield were prolonged by the APG management system, though the milk composition and quality were not significantly affected.

Dairy Sheep Grazing Management and Pasture Botanical Composition Affect Milk Macro and Micro Components: A Methodological Approach to Assess the Main Managerial Factors at Farm Level

Simple Summary

Studies on the management factors that affect milk components at the farm level are important for understanding how to transfer the results from experimental study. Plant phenological stages and partially fresh herbage intakes affect the lactose and milk fatty acid profile. The botanical composition of the grassland partially affects the milk’s phenol content. A few small relationships between plant phenols and milk colour could be of interest to explain the changes in milk colour parameters.

Abstract

The fatty acid profile, vitamins A and E, cholesterol, antioxidant power colour and the phenols profile of Sarda sheep milk from 11 commercial sheep flocks managed under permanent grassland were investigated. In each farm, the structural and managerial data and milk samples were collected during four periods (sampling dates, SD): January, March, May, and July. Data from the milk composition (fat, protein, casein, lactose, and somatic cell count), 68 fatty acids, 7 phenols, 1 total gallocatechin equivalent, ferric reducing antioxidant power, vitamins A and E, cholesterol, degree of antioxidant protection, and the colour (b *, a * and L *) were analyzed by multivariate factorial analysis using a principal component analysis approach. A proc mixed model for repeated measurement to point out the studied factors affecting significant macro and micro milk composition was also used. Only the first five components were detailed in this paper, with approximately 70% of the explained variance detected. PC1 presented the highest positive loadings for milk lactose, de novo FA synthesis and the BH intermediate, whereas OBCFA had negative loadings values. The PC2, LCFA, UFA, MUFA, vitamins E, and DAP showed positive loadings values, while SFA had a negative value. The PC3 showed a high positive loading for total phenols and non-flavonoids. PC4 presented a high positive loading for the milk macro-composition and negative values for n-3 FAs. The PC5 is characterized by high positive loadings for the a * and L * colour parameters whereas negative loadings were detected for the milk flavonoids content. These preliminary results could help to establish future threshold values for the biomarkers in milk sourced from grazing dairy sheep in natural, permanent pasture-based diets.

Organoleptic and Nutritional Traits of Lambs from Spanish Mediterranean Islands Raised under a Traditional Production System

Our aim was to characterize the organoleptic and nutritional properties of meat from suckling (one-month-old) and light (around three-months-old) lambs in local breeds on the Spanish Mediterranean islands, using meat from male lambs of the Mallorquina and Roja Mallorquina breeds. The lambs were kept with their mother at all times under an extensive management system and fed on mother’s milk until naturally weaned. In the Mallorquina breed, suckling lambs (n = 20) were slaughtered after weaning and the light lambs were bred using natural pasture (n = 20) or concentrate (n = 20), and the Roja Mallorquina light lambs were fed pasture and concentrate (n = 20). The pH, colour, texture, water-holding capacity, fatty acids, volatile compounds and sensorial attributes of the meat were analyzed. No differences in meat colour or texture were observed. The highest levels of non-desirable fatty acids were observed in lambs raised using concentrate. Light lambs showed a higher aldehydes content than suckling lambs. High notes of lactic acid and milk flavour were detected. Regardless of access to pasture or concentrate, continued access to mother’s milk during rearing influences the sensorial meat traits of these lambs, so we consider this type of management an optimal way of obtaining the traditional ‘Mediterranean lamb meat’.

High Milk Somatic Cell Counts and Increased Teladorsagia Burdens Overshadow Non-Infection-Related Factors as Predictors of Fat and Protein Content of Bulk-Tank Raw Milk in Sheep and Goat Farms

This paper presents the results of an extensive countrywide investigation performed in 325 dairy sheep flocks and 119 goat herds throughout Greece. The objectives of the study were (a) to investigate fat and protein content in the bulk-tank raw milk of small ruminant farms in Greece and (b) to identify factors potentially influencing that content and factors that can contribute to increased content. The mean fat/protein contents in bulk-tank raw milk of sheep and goats were 6.16 ± 0.05%/4.43 ± 0.01% and 4.77 ± 0.44%/3.23 ± 0.30%, respectively. Significant differences were seen in protein content between farms in the various parts of the country. For sheep, multivariable analyses revealed breed and age of lamb removal from dams as significant for fat content, and somatic cell counts, management system in the farm, administration of anthelmintic treatment during the last stage of pregnancy, and farmer education as significant for protein content. For goats, significant factors were month into lactation period, age of kid removal from dams, and breed for fat content, and somatic cell counts, month into lactation, grazing duration, and % Teladorsagia larvae in faecal samples for protein content. For concurrently high fat and protein content, in multivariable analyses, the following emerged as significant factors: somatic cell counts in milk, numbers of parasite eggs in faeces, and veterinary collaboration (sheep), and month into lactation and somatic cell counts in milk (goats). The results indicate that high somatic cell counts in milk (reflecting the presence of mastitis) and gastrointestinal parasitic infections (mainly Teladorsagia infection) appear to exert a more significant influence on fat and protein content of milk, in comparison to non-infection-related factors.

Effects of Lactobacillus fermentum HY01 on the quality characteristics and storage stability of yak yogurt

Lactobacillus fermentum HY01 is a probiotic strain screened from traditional yak yogurt, which can effectively relieve enteritis and constipation. This study aimed to evaluate the effects of HY01 as an adjunct starter on the quality and storage of yak yogurt. A total of 36 main volatile flavor substances were detected in all samples. In particular, more aldehydes, esters, and alcohols were detected in yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter MY105 (including Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus). The rheological results showed that the yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter MY105 had higher apparent viscosity and lower tan δ value compared with compared with traditional yak yogurt, yak yogurt with only L. fermentum HY01, and cow yogurt with L. fermentum HY01 and starter MY105. Meanwhile, the conjugated linoleic acid in the yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter was significantly higher than those in the HY01 group or the yogurt starter group alone. After 28 d of storage at 4°C, the number of HY01 in the yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter was still higher than 10⁷ cfu/mL, its acidity was lower than 110°T, and its syneresis was the lowest. The results indicated that L. fermentum HY01 could improve the flavor, texture, and storage properties of yak yogurt.

Sheep’s milk cheeses as a source of bioactive compounds

Since ancient times, sheep`s milk cheeses have been a part of a human diet. Currently, their consumption is of great interest due to its nutritional and health values. The aim of the article was to review the chemical composition of sheep’s milk cheeses and its main bioactive ingredients in the context of nutritional and health values. Sheep’s milk cheeses are rich in functionally and physiologically active compounds such as: vitamins, minerals, fatty acids, terpenes, sialic acid, orotic acid and L-carnitine, which are largely originate from milk. Fermentation and maturation process additionally enrich them in other bioactive substances as: bioactive peptides, γ-aminobutyric acid (GABA) or biogenic amines. Studies show that sheep’s milk cheese consumption may be helpful in the prevention of civilization diseases, i.e. hypertension, obesity or cancer. However, due to the presence of biogenic amines, people with metabolic disorders should be careful of their intake.