Seasonal variation of fatty acids composition of milk from grazing ewes in Thessaly, central Greece

Σκοπός αυτής της εργασίας ήταν η αξιολόγηση των μεταβολών του προφίλ των λιπαρών οξέων και της συγκέντρωσης του συζευγμένου λινολεϊκού οξέος (CLA) του γάλακτος από προβατίνες ελευθέρας βοσκής το χειμώνα (Δεκέμβριος και Ιανουάριος) και την άνοιξη (Απρίλιος και Μάιος) στη Θεσσαλία της κεντρικής Ελλάδας. Δεν παρατηρήθηκαν σημαντικές μεταβολές (P>0,05) στις φυσικοχημικές ιδιότητες (pH και περιεκτικότητα σε πρωτεΐνη, λακτόζη και συνολικά στερεά) του γάλακτος χειμώνα και άνοιξης. Ωστόσο, η περιεκτικότητα σε λιπαρά του ανοιξιάτικου γάλακτος ήταν χαμηλότερη (P<0,05) εκείνης του χειμώνα. Η περιεκτικότητα σε κορεσμένα λιπαρά οξέα του γάλακτος δεν μεταβλήθηκε σημαντικά (P>0,05) τόσο κατά τη διάρκεια του χειμώνα όσο και κατά τη διάρκεια της άνοιξης, ενώ η περιεκτικότητα σε πολυακόρεστα λιπαρά οξέα μεταβλήθηκε σημαντικά (P <0,05) σε κάθε έναν από τους τέσσερις μήνες που εξετάστηκαν. Παρ ‘όλα αυτά, στο γάλα της άνοιξης, η περιεκτικότητα των κορεσμένων λιπαρών οξέων μειώθηκε σημαντικά (P<0,05), αλλά η συγκέντρωση των μονοακόρεστων και πολυακόρεστων λιπαρών οξέων αυξήθηκε σημαντικά (P<0,05) σε σύγκριση με το γάλα του χειμώνα. Σε αντίθεση με τη μείωση των κορεσμένων λιπαρών οξέων στο ανοιξιάτικο γάλα, η περιεκτικότητα του κορεσμένου στεατικού οξέος (C18:0) παρουσίασε σημαντική αύξηση (P<0,05) στο γάλα της άνοιξης σε σύγκριση με εκείνη του χειμώνα. Στο γάλα του χειμώνα, τα επίπεδα του C18:2 cis-9, trans-11 CLA ήταν 0.89±0.05 και 0.98±0.03 g/100g FAMEs τον Δεκέμβριο και τον Ιανουάριο, αντίστοιχα, ενώ στο γάλα της άνοιξης τα επίπεδα του CLA αυξήθηκαν σημαντικά Ρ<0,05) σε 1.36±0.04 και 1.27±0.03 g/100g FAMEs τον Απρίλιο και τον Μάϊο, αντίστοιχα. Ο δείκτης αθηρογένεσης (ΑΙ), που σχετίζεται με λιπαρά οξέα που ευνοούν την πρόκληση αθηροσκλήρωσης αλλά και με λιπαρά οξέα που δεν ευνοούν την πρόκληση αθηροσκλήρωσης, βρέθηκε σημαντικά μικρότερος (P<0,05) στο γάλα της άνοιξης σε σχέση με εκείνο του χειμώνα.The aim of this work was to evaluate the changes in fatty acids (FAs) profile and conjugated linoleic acid (CLA) concentration of milk from grazing ewes in winter (December and January) and spring (April and May) in Thessaly, central Greece. No significant changes (P>0.05) in the physicochemical properties (pH and protein, lactose and total solids content) of winter and spring milk were observed. However, the fat content of spring milk was lower (P<0.05) than the winter milk. The saturated FAs content of milk was not significantly changed (P>0.05) during winter neither during spring, whereas the polyunsaturated FAs content was significantly changed (P<0.05) in each of the four months examined. Nevertheless, in the ovine milk of spring, the saturated FAs content was significantly decreased (P<0.05), but the monounsaturated and polyunsaturated FAs content was significantly increased (P<0.05) as compared to that of winter milk. In contrast to the saturated FAs decrease in spring milk, the saturated stearic acid (C18:0) content showed a significant increase (P<0.05) in the spring milk as compared to winter milk. In winter milk, the C18:2 cis-9, trans-11 CLA levels were 0.89±0.05 and 0.98±0.03g/100 g Fatty Acid Methyl Esters (FAMEs) in December and January, respectively, whereas, in spring milk, the CLA levels were significantly increased (P<0.05) to 1.36±0.04 and 1.27±0.03g/100 g FAMEs in April and May, respectively. The atherogenicity index (AI) associated with proatherogenic and antiatherogenic FAs was found significantly (P<0.05) lower in spring milk compared to winter milk

Effect of processing on the fatty acid composition of fresh and stored n-3 and n-6 eggs from hens fed diets supplemented with fish or sunflower oil

Eggs from hens fed diets supplemented with 3% fish or sunflower oil were either fresh submitted to pasteurization, hard-boiling or scrambling processing, or were first submitted to refrigerated storage at 4 degrees C for 60 d and then to processing. Fresh fish oil eggs showed a higher (P 0.05) on the fatty acid composition of fresh and stored eggs from both groups. In contrast, scrambling affected the fatty acid composition of fresh and stored eggs from both groups increasing (P <= 0.05) the proportions of oleic and linoleic acids, and decreasing (P <= 0.05) the proportions of the very long chain n-3 fatty acids

Effect of supplementation of the laying hen diet with olive leaves (Olea europea L.) on lipid oxidation and fatty acid profile of alpha-linolenic acid enriched eggs during storage

1. The aim of this study was to evaluate the effect of supplementation of the layer diet with olive leaves (Olea europea L.) on lipid oxidation and fatty acid profile of alpha-linolenic acid enriched eggs during refrigerated storage, and to compare this effect with alpha-tocopheryl acetate supplementation. 2. A total of 72 brown Lohmann laying hens, equally allocated to 3 groups, were fed on diets supplemented with 40 g/kg linseed oil, or linseed oil and olive leaves at 10 g/kg or linseed oil and alpha-tocopheryl acetate at 200 mg/kg. Collected eggs were analysed for fatty acid profile and lipid oxidation either fresh or following 60 d storage at 4 degrees C. 3. Results showed that olive leaves or alpha-tocopheryl acetate supplementation reduced lipid hydroperoxide concentration in fresh eggs but had no effect on their fatty acid profile and malondialdehyde (MDA) content compared to controls. 4. Refrigerated storage for 60 d decreased the proportions of PUFAs but increased those of MUFAs in eggs from the control diet, whilst it had no effect on the fatty acid composition of eggs from the diets supplemented with olive leaves or alpha-tocopheryl acetate, which in turn showed decreased concentrations of lipid hydroperoxides and MDA

Lipid and protein oxidation of alpha-linolenic acid-enriched pork during refrigerated storage as influenced by diet supplementation with olive leaves (Olea europea L.) or alpha-tocopheryl acetate

The objective of this study was to evaluate the effect of diet supplementation with olive leaves or alpha-tocopheryl acetate on lipid and protein oxidation of raw and cooked n-3 enriched-pork during refrigerated storage. Enrichment of pork with alpha-linolenic acid through diet supplementation with linseed oil enhanced (p 0.05) on protein oxidation during refrigerated storage while decreasing (p 0.05) on the fatty acid composition of pork but decreased (p 0.05) on protein oxidation in both raw and cooked alpha-linolenic acid-enriched chops stored and chilled for 9 days. Moreover, olive leaves and alpha-tocopheryl acetate supplemented at 10 g/kg and 200 mg/kg diet, respectively, exerted (p <= 0.05) a beneficial effect on the sensory attributes of cooked alpha-linolenic acid-enriched pork chops. (C) 2012 Elsevier Ltd. All rights reserved

Lipid oxidation of stored eggs enriched with very long chain n-3 fatty acids, as affected by dietary olive leaves (Olea europea L.) or alpha-tocopheryl acetate supplementation

The antioxidant potential of dietary olive leaves or alpha-tocopheryl acetate supplementation on lipid oxidation of refrigerated stored hen eggs enriched with very long-chain n-3 fatty acids, was investigated. Ninety-six brown Lohmann laying hens, were equally assigned into three groups. Hens within the control group were given a typical diet containing 3% fish oil, whereas other groups were given the same diet further supplemented with 10 g ground olive leaves/kg feed or 200 mg alpha-tocopheryl acetate/kg feed. Results showed that alpha-tocopheryl acetate or olive leaves supplementation had no significant effect on the fatty acid composition and malondialdehyde (MDA) levels of fresh eggs but reduced their lipid hydroperoxide levels compared to controls. Storage for 60 d decreased the proportions of polyunsaturated fatty acids (PUFAs) but increased those of monounsaturated fatty acids (MUFAs) in eggs from the control group, while had no effect on the fatty acid composition of the eggs from the other two groups, which showed decreased levels of lipid hydroperoxides and MDA. Therefore, the very long chain n-3 PUFAs in eggs were protected from undergoing deterioration partly by olive leaves supplementation and totally by alpha-tocopheryl acetate supplementation. In addition, incorporating tocopherols into eggs might also provide a source of tocopherols for the human diet. (C) 2012 Elsevier Ltd. All rights reserved

Effect of vacuum packaging on lipid oxidation of eel ( Anguilla anguilla) flesh during refrigerated storage

Recent trends towards extending the shelf-life of fresh eel during refrigerated storage have rendered the control of lipid oxidation increasingly important. Eel fat is very sensitive to oxidative deterioration because of its high content of polyunsaturated fatty acids. To delay or minimise oxidative deterioration of fresheel fat during refrigerated storage, the use of vacuum packaging was investigated. Lipid oxidation was assessed by monitoring malonaldehyde (MDA) formation in wild (n=10) and farmed (n=10) eel flesh samples at 0, 1, 2, 5 and 8 days of refrigerated storage in atmospheric air or under vacuum packaging, using a selective third-order derivative spectrophotometric method. The results clearly demonstrated the oxidative stability of vacuum packed eelflesh following storage for 8 days at 3±1oC and the significant oxidation of the atmospheric air stored eel flesh even after 1 day of refrigerated storage

Assessment of donkey milk chemical, microbiological and sensory attributes in Greece and Cyprus

This study aimed to assess the nutritional, hygienic and sensory characteristics of donkey milk produced in Greece and Cyprus. The average values for pH, fat, protein and lactose were 7.14, 0.52 g/100 mL, 1.22 g/100 mL and 7.01 g/100 mL, respectively, whereas aflatoxin M1 and beta-lactam residues were not detected in any sample. The microbiological analysis revealed very low somatic cell counts and total microbial counts, while Escherichia coli, Salmonella spp and Listeria monocytogenes were not detected in any sample. The sensory evaluation classified the milk as white, thin, with a slightly sweet pleasant taste, pleasant milky aroma, sweet flavour and no persistent aftertaste. © 2016 Society of Dairy Technology