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

Effects of Dietary Resveratrol and Black Soldier Fly (Hermetia illucens) Larvae Meal Supplements on Quail Egg Production, Quality, and Consumer Acceptance

This study aimed to examine the effects of supplementing a basal diet with resveratrol and black soldier fly (Hermetiaillucens) larvae meal on Manchurian Golden quail egg production and quality as well as consumer attitudes towards the quail eggs and their acceptability. Quail were allotted three treatments for a laying period of 3 months. The dietary treatment groups were those of a basal diet, a basal diet with 250 mg/kg resveratrol pliusACE, and a diet supplemented with 10% black soldier fly larvae meal (BSF). The BSF larvae meal supplement increased the live weight of the quail, but the differences in the mean egg production and egg external parameters between the experimental groups were insignificant. The egg yolk from the quail fed with resveratrol and BSF supplementation demonstrated lower (p < 0.001 and p < 0.01) pH compared with the quail fed a basal diet. Egg yolk colour showed lower (p < 0.05) lightness and lower (p < 0.01) yellowness and colour saturation in the group of quail fed with resveratrol supplement compared with BSF supplement. Resveratrol inclusion in the basal diet resulted in increased (p < 0.001) protein content in the yolk. BSF inclusion in the diet showed the effect by increasing (p < 0.001) dry matter in albumen. The total monounsaturated fatty acids, polyunsaturated fatty acids, and cholesterol content were not affected by the dietary treatment. The inclusion of BSF larvae meal in the diet increased the proportion of total saturated fatty acids and lowered the proportion of total trans fatty acids in yolk lipids and demonstrated less favourable ratios of fatty acids and nutritional indices, except for the peroxidisability index, and showed higher oxidative status (p < 0.05), flavour score, and overall egg acceptance compared with the quail fed on a basal diet.

Effect of Dietary Cold-Pressed Hempseed Cake Supplemented with Tomato Waste on Laying Hen Performance and Egg Yolk Lipid Profile and Antioxidant Status Before and After Storage

A ten-week study was conducted to investigate the effects of the dietary inclusion of HSC as a source of PUFAs together with a natural source of antioxidants such as DT or DTP on the performance of laying hens and egg quality, as well as the lipid profile, antioxidant content and oxidative stability of egg yolk before and after storage. A total of 96 laying hens (aged between 28 and 37 weeks) were divided into three groups of 32 birds each (eight replicate cages, four birds per cage) and were assigned randomly the following dietary treatments: a standard corn-soybean meal diet (C), a diet containing 20% hempseed cake and 4% dried whole tomato (HT) and a diet containing 20% hempseed cake and 4% dried tomato pomace (HTP). The incorporation of HSC and tomato waste (DT and DTP) into the diet of hens caused increases in feed intake (p < 0.05) and yolk color score without changing egg production, egg weight or feed conversion ratio (FCR). The HT and HTP diets ensured a lower content (p < 0.05) of cholesterol in the egg yolk but a higher content (p < 0.001) of n-3 FAs, especially of ALA (α-linolenic acid, 18:3n-3), EPA (eicosapentaenoic acid, 20:5n-3) and DHA (docosahexaenoic acid, 22:6n-3), which allowed for an increase in the hypo-/hypercholesterolemic FA ratio and a reduction in the n-6/n-3 FA ratio and TI (thrombogenicity index) value compared to those of C eggs. In addition, the inclusion of DT or DTP in the diet of laying hens increased the antioxidant content in the yolk, which led to an increase in the oxidative stability of the yolk lipids, evidenced by a decrease in the concentrations of MDA (malondialdehyde) in fresh eggs and those stored for 30 days at 4 °C. DTP exerted the most desirable effects because the egg yolk had the most intense color, the highest contents of n-3 FAs and natural antioxidants and the best oxidative stability of yolk lipids before and after egg storage. It was concluded that the simultaneous enrichment of the diet of laying hens with n-3 FAs and natural antioxidants (carotenoids, tocopherols and phenols), in addition to improving the color of the yolk, leads to eggs with a higher content of n-3 FAs and antioxidants, improved antioxidant activity and better PUFA stability during egg storage.

Effects of Enriched-in-Oleuropein Olive Leaf Extract Dietary Supplementation on Egg Quality and Antioxidant Parameters in Laying Hens

The objective of the present study was to evaluate the effects of an olive leaf extract obtained with an up-to-date laboratory method, when supplemented at different levels in laying hens' diets, on egg quality, egg yolk antioxidant parameters, fatty acid content, and liver pathology characteristics. Thus, 96 laying hens of the ISA-Brown breed were allocated to 48 experimental cages with two hens in each cage, resulting in 12 replicates per treatment. Treatments were: T1 (Control: basal diet); T2 (1% olive leaf extract); T3 (2.5% olive leaf extract); T4 (Positive control: 0.1% encapsulated oregano oil). Eggshell weight and thickness were improved in all treatments compared to the control, with T2 being significantly higher till the end of the experiment (p < 0.001). Egg yolk MDA content was lower for the T2 and T4 groups, while total phenol content and Haugh units were greater in the T2. The most improved fatty acid profile was the one of T3 yolks. The α-tocopherol yolk content was higher in all groups compared to T1. No effect was observed on cholesterol content at any treatment. Based on the findings, it can be inferred that the inclusion of olive leaf extract at a concentration of 1% in the diet leads to enhancements in specific egg quality attributes, accompanied by an augmentation of the antioxidant capacity.

Sunflower cake associated with crude glycerin in white laying hens diets: Performance and quality, antioxidant activity and lipid oxidation of eggs

The objective of this study was to evaluate the effects of sunflower cake inclusion and its association with crude glycerin in the diet of laying hens. A total of 320 laying hens with 39 weeks of age were distributed in a completely randomized design in a 4 × 2 factorial scheme with 5 replications of 8 birds. The studied factors were 4 inclusion levels of sunflower cake and 2 levels of crude glycerin. The inclusion of 210 g/kg of sunflower cake reduced egg mass and worsened feed conversion, and after the level 70 g/kg there was reduction in yolk coloration and specific density of eggs with or without the addition of glycerin in the diet. The addition of 70 g/kg of crude glycerin reduced the specific density of eggs in all levels of sunflower cake. There was increase in phenolic compounds, antioxidant capacity and antioxidant activity in eggs and reduction in lipid oxidation of yolks from fresh and stored eggs, with the inclusion of sunflower cake. The addition of crude glycerin increased the lipid oxidation of egg yolks. Therefore, it is possible to include up to 140 g/kg sunflower cake in the diet of laying hens, with or without crude glycerin, without impairing performance and egg quality, obtaining higher antioxidant capacity of eggs and lower lipid oxidation in yolks from fresh and stored eggs. The inclusion of 70 g/kg crude glycerin does not affect laying hens performance, however, it worsens shell quality and increases lipid oxidation in the liver and egg yolks.

Tea polyphenols increase the antioxidant status of laying hens fed diets with different levels of ageing corn

This study was conducted to evaluate the effects of ageing corn levels (stored for 4 years) with or without the supplementation of tea polyphenols (TPP) on the performance, egg quality and antioxidant status of laying hens. A total of 288 Lohmann commercial laying hens (63-week-old) were used under a 2 × 4 factorial arrangement with 4 levels of dietary ageing corn (0%, 25%, 50%, or 100%) and 2 levels of TPP (0 and 600 mg/kg) for 8 wk. Dietary ageing corn linearly decreased (P < 0.05) the egg production, serum total antioxidant capacity (T-AOC), liver glutathione peroxidase (GSH-Px) of laying hens, yolk index, yolk colour, 1,1-diphenyl-2-picrylhydrazyl (DPPH) value and the reducing power value of egg yolk, but it linearly increased (P < 0.05) the feed conversion rate, ovary malondialdehyde (MDA) content of laying hens, and the protein carbonyl content of egg yolk. Tea polyphenol supplementation increased (P < 0.05) the serum T-AOC, serum superoxide dismutase (SOD), liver SOD, liver GSH-Px, ovary SOD, GSH-Px, the expression of antioxidant-related genes of laying hens, albumen height, Haugh unit, DPPH value and the majority free amino acids of egg yolk, but it decreased (P < 0.05) the serum MDA content of laying hens, MDA and protein carbonyl of egg yolk. In conclusion, the ageing corn significantly reduced the performance, egg quality, antioxidant status and egg antioxidant capacity of laying hens, while TPP supplementation partially counteracted the adverse effects, especially antioxidant status and egg antioxidant capacity of laying hens.

Valorization of by-products from olive oil industry and added-value applications for innovative functional foods

BACKGROUND

In the last years, the consumption of olive oil has experienced a sharp rise due to its organoleptic and healthy properties and with this the wastes and by-products derived from the olive production and the olive oil industry have also increased causing important environmental and economic issues. However, the high content in bioactive compounds of these wastes and by-products makes that its recovery is both a great challenge and an excellent opportunity for the olive oil sector.

AIM OF THE REVIEW

This review encompasses the more outstanding aspects related to the advances achieved until date in the olive oil by-products valorisation and added-value applications for innovative functional foods.

CONCLUSION

Taking into account the information reported in this manuscript, the development of a multiproduct biorefinery in cascade using eco-friendly technologies interchangable seems a suitable stratety to obtaining high added value compounds from olive oil by-products with applications in the field of innovative functional foods. In addition, this would allow an integral valorization of these residues enhancing the profitability of the olive oil industry. On the other hand, the biocompounds fom olive oil by-products have been described by their interesting bioactivities with beneficial properties for the consumers' health; therefore, their incorporation into the formulation of functional foods opens new possibilities in the field of innovative foods. Future perspective: Despite the studies descibed in the literature, more research on the healthy properties of the recovered compounds and their interactions with food components is key to allow their reintegration in the food chain and therefore, the removal of the olive oil by-products.

Effect of dietary phytochemicals from tomato peels and rosehip meal on the lipid peroxidation of eggs from laying hens

The aim of the present study was to evaluate the effects of dietary supplementation with tomato peels (TP) and rosehip meal (RM) on their phytochemicals transfer to the egg, the antioxidant profile and the markers of lipid peroxidation in stored eggs. The experiment was conducted on 42-week-old TETRA SL laying hens, which were assigned to three dietary treatments with 30 birds each: the Control group (CON) received a corn-soybean diet containing 6% flaxseed meal without any by-product addition. Groups TP and RM received Diet CON with additionally 2% TP and 2% RM, respectively. Average daily feed intake, feed conversion ratio and laying percentage were not significantly changed by the dietary treatments. Compared to the other groups, the inclusion of dietary TP led to a significant increase in egg weight (p < 0.05) and vitamin E content in eggs (p < 0.05). The dietary inclusion of RM generated a higher vitamin A content in eggs compared to Groups CON and TP (p < 0.10). After 40 d of storage, in Groups CON, TP and RM the vitamin E contents of eggs deceased by 10.1%, 14.2% and 13.3%, respectively, whereas the reduction of the lutein and zeaxanthin concentration in eggs was more pronounced (by 24.8%, 21.8% and 25.5%, respectively). For the most primary as well as for secondary oxidation products, storage time had a significant influence (p < 0.05) on the degradation process of the eggs. After 40 d of storage, the most distinct reduction in the formation rate of secondary oxidation products was observed in Group RM (by more than 30%), while the reduction for Group TP amounted from 15% to 25%, when compared with Group CON. Therefore, the results of the present study showed a significantly positive effect of RM in retarding the lipid peroxidation process during storage.

Effects of dietary olive leaves on performance, carcass traits, meat stability and antioxidant status of fattening Mahabadi male kids

Twenty-four Mahabadi goat kids (5-6 months of age) were used to evaluate the effects of feeding olive leaves (OL) on performance, carcass traits and antioxidant status. The kids received three dietary treatments for 84 d with three levels of OL: 0 (control), 7.5 (OL7.5) and 15 (OL15) % (DM basis). Supplementation with OL had no effects on kid performance (P > 0.05). Total antioxidant capacity (TAC) was increased and malondialdehyde (MDA) concentration was decreased in plasma blood (P < 0.01) and Longissimus lumborum (LL) muscle (days 1, 4, 7 and 10) of kids (P < 0.01) with increasing level of OL in diet. The activity of glutathione peroxidase (GSH-Px) in LL muscle was increased (P < 0.05) in OL15 fed kids compared with control group. Also, glucose content of serum was decreased by adding OL to kid diets (P < 0.01). Finally, inclusion of OL to kid diets resulted in similar growth performance compared to alfalfa feeding, and improved the antioxidative potential of LL muscle.

Olive Leaves Extract from Algerian Oleaster (Olea europaea var. sylvestris) on Microbiological Safety and Shelf-life Stability of Raw Halal Minced Beef during Display

Oleaster (wild olive tree) by-products represent a renewable and low-cost source of biopolyphenols. Leaf extracts (sylv.OLE) of Algerian oleaster, locally called a'hachad (Olea europaea subsp. europaea var. sylvestris), were applied at 1 and 5% (v/w) to raw Halal minced beef (HMB) in order to test its safety and shelf-life prolongation during retail/display. The total phenolic compound content in the extract was 198.7 ± 3.6 mg gallic acid equivalent. Ten compounds were identified in the sylv.OLE by High Performance Liquid Chromatography/Diode Array Detector (HPLC/DAD), of which oleuropein was the most abundant (43.25%). Samples treated with 5% sylv.OLE had significantly higher antimicrobial and antioxidant effects than those treated with 1% extract (p < 0.05). The addition of sylv.OLE reduced psychrotrophic counts as well as the level of pathogens (Salmonella enterica ser. Enteritidis and Shiga toxin-producing Escherichia coli O157:H7). A thiobarbituric acid reactive substance (TBARS) value of 2.42 ± 0.11 was reached throughout six days of retail/display in control samples, while the addition of 5% sylv.OLE reduced TBARS value by 58% (p < 0.05). The presence of sylv.OLE at the tested concentrations did not negatively influence the overall acceptability and bitterness of HMB.

Effects of Olive Leaf and Marigold Extracts on the Utilization of Nutrients and on Bone Mineralization using Two Different Oil Sources in Broilers

The aim of this study was to investigate the effects of olive leaf and marigold extracts on the apparent total tract digestibility (ATTD) of the principal nutrients and energy, as well as on mineral utilization (Ca, P, Mg, Mn, Fe, Cu and Zn) in relation to bone characteristics in broilers fed walnut- or linseed oil-supplemented diets. Thirty-six 12-day-old commercial broilers Ross 308 were reared in metabolic cages, assigned to one of the six dietary treatments (3 × 2 factorial design): three supplements (not supplemented, olive leaf extract, or marigold extract), and two oils (walnut or linseed oil). The results showed that the marigold extract reduced Zn and P balances and tended to lower the balance of ash and Mg, and the ATTD of Zn and Mg. Diets with linseed oil increased the ATTD of acid detergent fiber and reduced the ATTD of the organic residue and Cu. No differences in the bone characteristics of tibia were observed between treatments. These results indicated that the inclusion of marigold extract had a negative effect on the Zn and P balance, and that neither extract had any major effect on the digestion and utilization of energy and other investigated nutrients, or on bone mineralization, irrespective of the oil source included in the diet.

Effect of storage and cooking on the fatty acid profile of omega-3 enriched eggs and pork meat marketed in Belgium

The fatty acids (FA) profile was determined in n-3 enriched (Columbus™) Belgian eggs and pork in order to evaluate to what extent the n-3 fatty acids, which are very sensitive to oxidation, are resistant to storage or cooking. In standard eggs or pork, no change of the fatty acid profile was observed after storage or cooking without culinary fat, as well as in Columbus™ eggs and pork after storage. Some cooking processes (eggs in custard and meat in oven) induced a slight significant loss of n-3 fatty acids in Columbus™ eggs or pork (11.1% in fat from eggs cooked in custard vs. 15.3% in raw Columbus™ eggs and 11.0% in fat from oven cooked meat vs. 11.6% in raw Columbus™ meat). As expected, when Columbus™ pork is cooked with culinary fat, its fatty acid profile is modified according to the nature of the fat used.