The Effect of Milking Frequency, Breed, and Stage of Lactation on the Milk Fat Globule Size and Fatty Acid Composition in Sheep's Milk.

This study examined the effects of milking frequency, breed, and stage of lactation on the milk fat globules (MFG) size and fatty acids (FA) composition of sheep milk. Milk from Karagouniko (n = 13) and Chios (n = 13) ewes was sampled postpartum on the 93rd, 101st, 108th, 121st, 156th, and 188th days of lactation. On the 108th day, the ewes were divided randomly into two milking groups: Once daily at 06:00 a.m. or twice daily at 06:00 a.m. and 16:00 p.m. Morphometric characteristics of MFG and FA composition were determined for each sample. Once versus twice daily milking had no effect on MFG dimensions, which tended to vary according to breed (smaller MFG were secreted from Chios with p = 0.065), while the stage of lactation had a significant effect (p < 0.001). FA composition differed significantly according to the stage of lactation and breed. The FA profile of the Karagouniko breed showed higher concentrations of short-chain FA. The milk samples from late lactation were characterized by higher concentrations of mono-unsaturated FA (MUFA) compared to early and mid-lactation. Moreover, correlations were found between the average diameter of MFG and FA concentrations, where the size of MFG was positively correlated with saturated FA (SFA) and negatively correlated with MUFA.

Physicochemical, Microbiological and Sensory Characteristics of White Brined Cheese Ripened and Preserved in Large-Capacity Stainless Steel Tanks.

The objective of the present study was to investigate the effect of ripening and preservation containers on the physico-chemical, microbiological, and textural characteristics, and volatile profile of white cheese. White cheeses were manufactured on an industrial scale using large-capacity stainless steel tanks (SST) of 500 kg, and the respective control samples in tin containers (TC) of 17 kg. No significant differences (p > 0.05) in fat in dry matter and total protein content were observed at 60 days of ripening between the TC and SST cheeses. After 60 days, of ripening, the moisture of the cheeses in SST and TC did not show significant statistical differences (p > 0.05). No significant differences (p > 0.05) were observed between the TC and SST cheeses in the mineral concentration (Ca, Mg, K, and Na) and textural characteristics. Similar results of pH and bacterial counts, as well as absence of yeasts and molds, were observed during ripening and preservation time in both groups of cheeses. Furthermore, proteolysis was not affected statistically significantly (p > 0.05). A moderately increased rate of ripening for the cheeses in TC was observed up to 90 days but, at 180 days, proteolysis was similar in both groups of cheeses. Regarding the SFA, MUFA, and PUFA content, no significant differences (p > 0.05) were observed between the TC and SST cheeses. A total of 94 volatile compounds were identified in the volatile fraction of both the SST and TC cheeses. Organic acids and alcohols were the most abundant classes of volatile compounds that were identified. The flavor and texture scores in the TC and SST cheeses were similar (p > 0.05). Overall, the TC and SST cheeses did not show any significant statistical difference in any of the analyzed parameters.

Hesperidin and Naringin Improve Broiler Meat Fatty Acid Profile and Modulate the Expression of Genes Involved in Fatty Acid ß-oxidation and Antioxidant Defense in a Dose Dependent Manner.

The beneficial properties of the flavanones hesperidin and naringin as feed additives in poultry have lately been under investigation. In broilers, both flavanones have been shown to exhibit antioxidant properties while their individual effects on fatty acid (FA) composition and the underlying molecular mechanisms of their activity have not been explored. Here, we studied their effects on broiler meats' FA profiles and on the expression of genes related to lipid metabolism, antioxidant defense and anti-inflammatory function. The experimental design comprised six treatment groups of broilers, each supplemented from day 11 until slaughter at 42 days with hesperidin, naringin or vitamin E, as follows: the E1 group received 0.75 g of hesperidin per kg of feed, E2 received 1.5 g hesperidin/kg feed, N1 received 0.75 g naringin/kg feed, N2 received 1.5 g naringin/kg feed, vitamin E (VE) received 0.2 g a-tocopheryl acetate/kg feed, and the control group was not provided with a supplemented feed. The VE treatment group served as a positive control for antioxidant activity. An analysis of the FA profiles of the abdominal adipose tissue (fat pad), major pectoralis (breast) and biceps femoris (thigh) muscles showed that both hesperidin and naringin had significant effects on saturated FA (SFA), polyunsaturated FA (PUFA) and omega n-6 content. Both compounds reduced SFA and increased PUFA and n-6 content, as well as reducing the atherogenicity and thrombogenicity indices in the breast muscle and fat pad. The effects on the thigh muscle were limited. An analysis of gene expression in the liver revealed that naringin significantly increased peroxisome proliferator-activated receptor alpha (PPARα), Acyl-CoA oxidase 1 (ACOX1) and glutathione disulfide reductase (GSR) expression. In the breast muscle, both hesperidin and naringin increased fatty acid synthase (FASN) expression and hesperidin increased the expression of adiponectin. In brief, both hesperidin and naringin supplementation beneficially affected FA profiles in the breast meat and fat pad of broiler chicken. These effects could be attributed to an increase in FA ß-oxidation since the increased expression of related genes (PPARα and ACOX1) was observed in the liver. Furthermore, the antioxidant activity of hesperidin and naringin previously observed in the meat of broilers could be attributed, at least partly, to the regulation of antioxidant defense genes, as evidenced by the increased GSR expression in response to naringin supplementation.

Microbial Profile Antibacterial Properties and Chemical Composition of Raw Donkey Milk.

The human interest in donkey milk is growing due to its nutritional, functional properties and excellent microbiological quality according to published reports. However, more research needs to be conducted to assess the above variables from various breeds. In the present study, milk samples were collected from 17 Cypriot and six Arcadian healthy Greek donkeys. The microbiological quality, somatic cell counts (SCC), chemical composition analysis, and antimicrobial activity of the samples was assessed. In addition, clustering and identification of the bacterial composition was performed by RAPD-PCR and 16S rDNA sequencing, respectively. The good microbiological quality of the samples as estimated by the total aerobic mesophilic and psychrotrophic counts, which ranged from 2.18 to 2.71 log CFU/mL and from 1.48 to 2.37 log CFU/mL, respectively, was also verified. SCC were below 4.4 log CFU/mL. However, potential pathogenic species of Staphylococcus aureus, Bacillus cereus, and Clostridium spp. were enumerated in the milk of both breeds. The gross chemical composition showed mean values for fat, protein, and lactose from 0.82% to 1.24%, 1.22% to 1.87%, and 6.01% to 6.78%, respectively. All milk samples exhibited an antimicrobial activity against St. haemolyticus and Listeria monocytogenes, although quality control measures should be taken for health and safety prior to human consumption.

The effects of hesperidin or naringin dietary supplementation on the milk properties of dairy ewes.

BACKGROUND: Fortification of animal products with natural bioactive compounds appears to improve their quality and protects consumers against oxidation effects. An experiment was therefore conducted to examine the effects of hesperidin or naringin on milk oxidative stability, yield, composition, coagulation properties, and the fatty acid profile in dairy sheep. Thirty-six Chios ewes were assigned to four groups. A control group was fed a concentrate diet without supplementation. The other three groups were provided with the same diet further supplemented with hesperidin (6000 mg kg-1 ), naringin (6000 mg kg-1 ), or α-tocopheryl acetate (200 mg kg-1 ). The efficacy of flavonoids after a change in diet composition that lowered milk oxidation values by itself was also tested. The duration of the experiment was 28 days with alfalfa hay being the only forage source for the first 14 days, whereas after the 15th day a mixture of alfalfa hay and wheat straw (65:35) was provided. RESULTS: The oxidative stability of milk was improved after 14 days of addition of the examined flavonoids (P < 0.05). Milk malondialdehyde (MDA) values were also decreased as a result of flavonoid dietary supplementation, 14 days after the modification of the forage source. On the other hand, no significant differences in yield, chemical composition, coagulation properties, and fatty acid profile of ewe milk were observed among the treatments throughout the experiment. CONCLUSION: Enrichment of dairy ewes' diets with hesperidin and naringin might be effective in improving milk's oxidative stability without any effects on the milk's chemical composition, coagulation properties, and fatty acid profile. © 2019 Society of Chemical Industry.

Greek Graviera Cheese Assessment through Elemental Metabolomics-Implications for Authentication, Safety and Nutrition.

This study presents the comprehensive elemental profile of Greek Graviera (Gruyère) cheeses. In total, 105 samples from nine different geographic regions produced from sheep, goat and cow milk and their mixtures were assessed. Elemental signatures of 61 elements were investigated for determination of geographic origin and milk type. Regional and milk type classification through Linear Discriminant Analysis was successful for almost all cases, while a less optimistic cross validation exercise presented lower classification rates. That points to further research using a much larger sample set, increasing confidence for cheese authentication utilizing also bioinformatics tools under development. This is the first study reporting signatures of 61 elements in dairy products including all sixteen rare earth elements and all seven precious metals. Safety and quality were assessed regarding toxic and nutritive elements. According to both EU and USA regulations and directives, Graviera is a nutritional source for trace and macro elements with low levels of toxic elements.

The effect of extended milking intervals (24, 48 and 72 h) on milk yield, milk composition, mammary physiology and welfare traits in dairy ewes.

The majority of the work today regarding the effects of extended milking intervals has focused on dairy cattle and only to a limited extent on dairy goats and sheep. The aim of this study was to investigate the effect of different non-milking intervals on milk yield and composition, mammary physiology and welfare indices in dairy ewes. Thirty-six multiparous ewes in late lactation were allocated to one of four groups of nine and subjected to 24, 48 or 72 h of non-milking or normal milking interval (12 h) (group A, B, C and D, respectively). Data showed that there were no significant differences in milk yield among the experimental groups during the third day after re-milking. Furthermore, no significant differences in milk lactose, protein and fat concentration among the experimental groups were observed after 7, 14 and 21 d of re-milking, respectively. Non-milking for 72 h resulted in a temporary increase of sodium concentration, Na + /K + ratio and enzymatic activities of plasmin (PL), plasminogen (PG) and plasminogen activator (PA) in milk. However, these parameters had similar values among the experimental groups on day 5 after re-milking. The concentration of lactose in blood was also significantly increased as a result of the 72 h non-milking interval and returned to its initial levels the second day after re-milking. These data, taken together, suggest that early involution events that occurred as an effect of non-milking were fully reversible within a short period of time. Finally, no significant signs of welfare impairment were observed in ewes due to extended milking intervals. In conclusion, non-milking up to 72 h had no negative effects on milk yield and composition, mammary physiology and welfare parameters in dairy ewes.