The effect of olive leaves supplementation on the feed digestibility, growth performances of pigs and quality of pork meat

Feeding pigs with hazelnut skin and addition of a concentrated phenolic extract from olive-milling wastewaters during pork processing: Effects on salami quality traits and acceptance by the consumers

Two groups of ten barrows received a conventional- (CTRL) or an experimental- (HZL) finishing diet containing 11% of hazelnut skin. From each barrow, two types of salami (namely, NITR, and PHEN) were obtained. NITR salami was added with E250 and E252. The latter were replaced by a phenolic concentrated extract from olive-milling wastewaters in PHEN salami. Salami fatty acids (FA), antioxidant capacity, lipid and color stability during refrigerated storage were assessed. A consumer test was also performed. Feeding strategy minimally affected the investigated parameters. PHEN salami had lower TBARS than NITR salami (P-value <0.001) during refrigerated storage despite comparable antioxidant capacity and similar PUFA content. Moreover, within CTRL group, lipid oxidation was lower in PHEN than NITR salami (P-value = 0.040). At the blind taste, dietary treatment did not affect salami sensorial properties nor consumer acceptance, whereas NITR salami showed better color (P-value = 0.036). Interestingly, HZL and PHEN salami showed improved sensorial properties and consumer acceptance after that consumers received information on salami origin.

Effects of feeding bergamot pulp and olive leaves on performance and meat quality in Apulo-Calabrese pigs

To determine the effects of dietary inclusion of bergamot pulp and olive leaves on pork quality, thirty-six barrows (Apulo-Calabrese; 112.5 ± 7.40 kg initial bodyweight) were randomly assigned to four experimental treatments and fed for 100 days a control diet (control group) or a diet similar to the control diet in which part of the cereals were replaced with 20 % (DM on the diet fed) of ensiled bergamot pulp (dry matter on the diet fed, EBP group) or olive leaves (OLL group) or a 1:1 mixture of both by-products (BPOL group). In the present study, the dietary administration of by-products did not influence the accumulation of IMF (P > 0.05) in meat. As for individual fatty acids, no differences were observed among groups. However, the dietary supplementation of bergamot pulp tended to increase (P = 0.073) the level of α-linolenic acid in meat. In raw and cooked meat TBARS values were higher (P < 0.001) in the Control group than in EBP, OLL and BPOL groups. The integration of 20 % of bergamot pulp and/or olive leaves by-products increased the levels of tocopherol and phenolic compounds in the diets, positively influencing the shelf life of meat. No effect of diet was observed on animal performance. The results of present study indicated mainly that partial replacement of cereals with 20 % DM on the diet fed of ensiled bergamot pulp and olive leaves, either alone or in combination, in the pig's diet led to greater oxidative stability of the meat.

Dietary supplementation with olive oil co-products rich in polyphenols: a novel nutraceutical approach in monogastric animal nutrition

In recent years, the increased demand for agri-food products to feed livestock species has stimulated research to identify novel solutions for the valorization of natural waste, according to the modern concept of a circular economy. Numerous studies have shown the use of plant-derived and agro-industrial co-products that are sources of bioactive molecules for preparing animal feeds. Supplementation with co-products derived from the extraction of olive oil (i.e., olive pomace, olive mill wastewater, olive cake and olive leaf) in diet has been widely considered in recent decades, because these wastes are produced in high quantity and their re-use represents an innovative economic and environmental strategy. Olive oil co-products are characterized by various bioactive molecules such as polyphenols, carbohydrates, proteins, and lipids. Among them, polyphenols are the nutraceuticals most studied, showing to promote health effects in both humans and animals. Olive oil co-products and their phenolic extracts have shown many beneficial and promising effects when added to the diets of monogastric animals, by improving performance parameters and maintaining the oxidative status of meat and derived products. This review provides an update on the use of olive co-products in monogastric animal (swine, poultry and rabbit) diets and their effects on the productive performance, meat quality characteristics and gut health status.

Effects of Anthocyanin Supplementation and Ageing Time on the Volatile Organic Compounds and Sensory Attributes of Meat from Goat Kids

The aim of this study was to assess the effects of dietary anthocyanin addition on volatile compounds of meat from goat kids during ageing. For this work, 60 male and female kids were divided into two groups: red orange and lemon extract (RLE group; n = 30), which received an RLE extract (90 mg/kg of live weight); and control (CON group; n = 30). The phytoextract in dry powder form was rich in bioflavonoids such as flavanones (about 16%) and anthocyanins (about 3%). After slaughtering, the longissimus thoracis et lumborum muscle was aged at 4 °C. The volatile organic compound (VOC) and sensorial analyses were carried out at 1, 3 and 7 days. A total of 10 chemical families were identified during the ageing process. Aldehydes were the most abundant VOC, followed by ketones and alcohols. Their contents increased during the process, showing after 7 days of ageing mean values of 20,498, 2193 and 1879 ng/g of meat, respectively. Regarding dietary effects, carboxylic acids, hydrocarbons and thiols presented significant differences between treatments, with higher carboxylic acid contents observed in RLE samples (437 vs. 467 ng/g of meat for CON and RLE batches, respectively; p < 0.05). On the contrary, hydrocarbons (436 vs. 254 ng/g of meat for CON and RLE batches, respectively) and thiols (160 vs. 103 ng/g of meat for CON and RLE batches, respectively) displayed significantly (p < 0.01) higher amounts in CON compared to the RLE group. Regarding ageing time, the tenderness, juiciness, odour and overall assessment parameters showed significantly higher scores at the end of the whole process (p < 0.05). On the other hand, only odour displayed significant differences between treatments, reaching higher scores in CON samples (p < 0.05). Therefore, ageing time improved the sensorial properties (tenderness, juiciness, odour and overall assessment) and the VOC content, whereas the inclusion of anthocyanins in the kids' diet did not have a great impact on the properties of aged meat.

Dietary oleuropein extract supplementation and its combination with α-tocopheryl acetate and selenium modifies the free fatty acid profile of pork and improves its stability

BACKGROUND

Olive-derived antioxidants have been shown to affect the oxidative status of meat and have also been associated with greater consumption of glucose, which might affect glycogen stores and muscle characteristics. This study evaluated the effect of oleuropein extract supplementation (OLE) versus vitamin E + Se (VE), and their combination (VEOLE), in pig diets, on pH, drip loss, the proportion of free fatty acids, and meat stability, and their prediction by blood oxidative status markers.

RESULTS

The drip loss of muscle was lower in antioxidant-supplemented groups when compared with controls. α-Tocopherol concentration and total fatty acids profile were not affected by dietary oleuropein supplementation. However, OLE and VEOLE had lower free n-3 polyunsaturated fatty acid (PUFA) levels when compared with VE and tended to have higher free monounsaturated fatty acid (MUFA) levels. Furthermore, the VEOLE group had lower free n-6 PUFA levels when compared with controls or VE, whereas the OLE group had intermediated values. Muscle samples from pigs subjected to the antioxidant-mixed supplementation (VEOLE) had lower malondialdehyde concentration when compared with the others. The VE and OLE groups showed intermediate malondialdehyde values. Chilled meat stability was highly correlated with antioxidant status in vivo.

CONCLUSION

The administration of 96 mg oleuropein kg^-1 feed produced similar meat quality characteristics as the use of 100 mg kg^-1 α-tocopheryl acetate +0.26 mg kg^-1 sodium selenite and it would be an interesting alternative in Mediterranean countries. The VEOLE group was the most effective for reducing lipid oxidation and for the production of polyunsaturated free fatty acids in meat, which would result in lower rancidity formation and better aroma development in products. © 2020 Society of Chemical Industry.

Olive Tree in Circular Economy as a Source of Secondary Metabolites Active for Human and Animal Health Beyond Oxidative Stress and Inflammation

Extra-virgin olive oil (EVOO) contains many bioactive compounds with multiple biological activities that make it one of the most important functional foods. Both the constituents of the lipid fraction and that of the unsaponifiable fraction show a clear action in reducing oxidative stress by acting on various body components, at concentrations established by the European Food Safety Authority's claims. In addition to the main product obtained by the mechanical pressing of the fruit, i.e., the EVOO, the residual by-products of the process also contain significant amounts of antioxidant molecules, thus potentially making the Olea europea L. an excellent example of the circular economy. In fact, the olive mill wastewaters, the leaves, the pomace, and the pits discharged from the EVOO production process are partially recycled in the nutraceutical and cosmeceutical fields also because of their antioxidant effect. This work presents an overview of the biological activities of these by-products, as shown by in vitro and in vivo assays, and also from clinical trials, as well as their main formulations currently available on the market.

Supplementation Effect of Oleuropein Extract Combined with Betaine, Magnesium, and Vitamin E on Pigs' Performance and Meat Quality Characteristics

Simple Summary

Oleuropein, betaine, magnesium, and vitamin E show antioxidant and/or metabolic effects on the organism that are reflected, in many cases, in performances and meat quality. This study evaluated whether the combination of these nutrients at two doses manifest different effects on the final product. Both combinations were enough to improve the oxidative status of pigs, although performances were not affected. However, the higher doses increased n-6 and n-3 PUFA in the triglycerides and free fatty acid fractions that resulted in meat that was more susceptible to oxidation.

Abstract

This study evaluates the effect of the dietary combination of oleuropein extract (1200 mg/kg) and betaine (1000 mg/kg), magnesium oxide (600 mg/kg), and α–tocopheryl acetate (400 mg/kg), or a half-dose of these compounds, on pigs’ performance, oxidative status, and meat quality characteristics (drip loss, TBARS, and texture and fatty acid profile of intramuscular fat). Sixty-six barrows and females were slaughtered at 120 kg of BW. Performance and carcass yield were not changed by treatments. The high-dose mixture resulted in higher serum ferric reducing/antioxidant power (p = 0.0026), lower glucose (p = 0.03) and a tendency to have lower serum TBARS (p = 0.07) when compared to control. Percentage of drip loss, moisture content, intramuscular fat, or texture parameters were not modified by dietary treatments. Pigs supplemented with the high-dose mixture had higher PUFA (p = 0.0001), n-6 (p = 0.0001), n-3 (p = 0.0095) and lower MUFA (p = 0.0064) in the neutral lipid fraction of intramuscular fat. Free PUFA, mainly n-3 fatty acids (p = 0.0009), were also higher in the meat of pigs fed the high-dose mixture compared with the others. A higher mobilization (neutral to free fatty acids hydrolysis) of n-3 and MUFA fatty acids in the muscle from pigs fed the high-dose mixture was observed. However, dietary mixture supplementation tended to increase MUFA (p = 0.056) and decrease the total PUFA (p = 0.0074) proportions in muscle polar lipids. This specific fatty acid composition of meat from pigs supplemented with the high-dose mixture could be responsible for the higher meat lipid oxidation observed in this group when compared to the other groups. Consequently, the low-dose mixture would be more adequate for maintaining the oxidative status of pigs and, meat lipid stability.

Acid Hydrolysis of Olive Tree Leaves: Preliminary Study towards Biochemical Conversion

Olive tree leaves, an abundant agricultural by-product without enough industrial market outlets, are presented in this study as a relevant resource of available carbohydrates to be chemically treated for monomeric sugar production. Characterization of two main granulometric fractions is the starting point for testing the specific effect and the relevance of three main factors (time, temperature, and sulfuric acid concentration) on diluted acid hydrolysis with respect to oligosaccharides, simple sugars, and fermentation inhibitory compounds production. The selected conditions (100 ∘ C, 90 min, and 6% w/w H 2 SO 4 ) to perform the small scale hydrolytic process, considering response surface methodology (2 3 factorial design with center points), implied production of acetic acid and hydroxymethylfurfural in concentrations not exceeding 1.10 kg m − 3 and 0.25 kg m − 3 , respectively. Thus, these experimental conditions were the reference framework to evaluate the effect of a meaningful scaling stage in a hydrolysis reactor, considering kinetic parameters based on hydrolysis rates and d-glucose and d-xylose generation.

Effect of local diets on nutritional and sensory quality of meat of indigenous goats in Tunisian arid regions

The valorization of natural resources in small ruminants feeding can reduce the cost of feed and produce good meat quality. The objective was to evaluate the effects of local feed resources on the physico-chemical aspects, the sensorial characteristics and the fatty acid profile of goat kid's meat. Twenty-six kids are divided in three groups (average body weight = 15.85 kg; age = 4 months). The groups received oat hay (group control C), dried olive leaves + dried Stipa tenacissima (group OL) or grass hay (group Ko). The animals were slaughtered after 90 days of experience, with an approximate final live weight of 18.5 kg. Total solids, pH, fat, crude protein, vitamin, cholesterol and fatty acid contents of meat were determined. The OL group had the highest ultimate pH (6.82 vs. 6.73); cooking loss, gross composition (total solids, protein and fat), cholesterol and colour coordinates (L, a* and b*) were similar among groups. The vitamin E, affected by diet, was higher in group OL than the other groups (3.71 mg/kg vs. 1.32 and 2.17 mg/kg, respectively, for C and Ko groups). Moreover, meat from this group showed the highest saturated fatty acid. Unsaturated fatty acids content was higher in the meat of C and Ko groups. On the other side, polyunsaturated fatty acid level was not affected by the diet treatment. The n6/n3 ratio was significantly affected by the diet; it was lower in meat of groups Ko and OL (3.17 and 3.38 respectively). The feeding effect on sensory quality of meat was not significant.

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.

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.

Use of phenolic compounds from olive mill wastewater as valuable ingredients for functional foods

Olive mill wastewater (OMW) is a pollutant by-product from the virgin olive oil production. Its high content in phenolic compounds makes them play an important role for their use in foods, for their high antioxidant significance. The present paper gives an overview on the techniques for OMW valuable ingredient separation, focusing on the most effective ones for their use in food products as functional ingredients. We report on effective methods to recover OMW phenolics, and give several examples on the use these extracts in foods. When added into vegetable oils, their effect on retarding lipid oxidation improves the oxidative status of the product, whilst several challenges need to be faced. OMW phenolic extracts were also used in food emulsions, milk products or other model systems, showing promising results and little or no negative impact on the sensory characteristics or other properties. Their possible use as antimicrobial agents is also another promising approach, as positive results were obtained when applied in meat products. Other examples of using natural phenolic extracts from other sources are suggested also for OMW extracts, to expand their use and thus to improve the nutritional and technological quality of foods.

Antioxidant protection of proteins and lipids in processed pork loin chops through feed supplementation with avocado

This study was conducted to analyze the impact of dietary avocado on the oxidative stability of lipids and proteins during pork processing. Loins from control (fed basic diet) and treated pigs (fed on avocado-supplemented diet) were roasted (102 °C/20 min) and subsequently packed in trays wrapped with oxygen-permeable films and chilled at 4 °C for 12 days. At each processing stage (raw, cooked and cooked & chilled), pork samples from both groups were analyzed for the concentration of TBARS, the loss of tryptophan and free thiols, and the formation of protein carbonyls, disulphide bonds and Schiff bases. Processing led to a depletion of tryptophan and sulfur-containing amino acids and an increase of lipid and protein oxidation products. Dietary avocado was not able to protect against the oxidation of tryptophan and thiols but cooked & chilled loins from treated pigs had significantly lower concentration of lipid and protein carbonyls than control counterparts. Likewise, dietary avocado alleviated the formation of Schiff bases during cooking. These results illustrate the benefits of dietary avocado on the oxidative stability of processed pork loins.

Growth, feed intake and carcass characteristics of indigenous goats fed local resources in Tunisian arid land

Native genetic resource of goats is a pivotal source for meat and milk in southern Tunisia. Feeding is one of the most important activities of goat husbandry. Perceptions on the role of native feed resources for growth and carcass characteristics have not been well studied. Therefore, the present study was designed to help understand and to compare the influences of local forage resources (grass hay, dried olive leaves, Stipa tenacissima and oat hay) on growth performance and carcass characteristics of kids. The kids with the age of 4 months (average live bodyweight of 15 ± 58 kg) were selected for the study. The three study groups in the 90-day trial were as follows: Group C, where animals received oat hay only (control), Group OL, where animals received olive leaves (dried) + S. tenacissima and Group GH, where animals received grass hay. A daily allowance of commercially available concentrate (305 g DM/day) was offered to all groups (making about half of the total DM intake). At the end of the experiment, all animals were slaughtered. Statistical analysis showed that total DM intake was lower (P < 0.001) in C group (490.77 g) than the other two groups having similar DM intake (619.22 and 589.28 g for OL and GH, respectively). Average daily gain was comparable for the three groups (38.33, 40.71 g and 39.52, respectively, for C, OL and GH), with similar final liveweights. Cold carcass weight and carcass yield were not affected by diet treatment. Diet had no significant effect on individual organ weights and carcass composition. The use of the local forage resources evaluated in this trial could be used for the local goat population without loss of productivity when they make up about half of the diet along with a concentrate feed.

Plant extracts in heavy pig feeding: effects on quality of meat and Cremona salami

The influence of dietary plant extracts (PE) from Lippia spp. titrated in verbascoside (0 and 5 mg/kg feed) during the last period of heavy fattening pig on fresh meat and on Cremona (Protected Geographical Indication) salami quality were evaluated. Meat quality was measured as thiobarbituric acid reactive substances (TBARS), chemical composition, drip and cooking loss and quality of Cremona salami was assessed as chemical composition, TBARS, cholesterol content, fatty acid composition and sensory analysis. No differences were found for proximate composition either in raw meat or in salami. A lower oxidative (P < 0.05) susceptibility was found in the Biceps femoris muscle of the PE group. Sensory analysis of salami showed that dietary integration did not affect the characteristics of the Protected Geographical Indication product excepting for the colour that resulted more intensely in the PE group. PE significantly lowered the saturated fatty acid content and increased the monounsaturated fatty acids of salami. These results need to be confirmed in further studies.

Efeito da incorporação de folhas de oliveira (Olea europaea L.) no desenvolvimento e qualidade da carne de frangos

Resumo Foi realizada suplementação de folhas de oliveira na ração de frangos na quantidade de 5 e 10 g de folhas/kg de ração e acompanhou-se o desempenho dos animais durante seu crescimento. Depois do abate, as coxas e sobrecoxas foram coletadas e armazenadas a 4 °C (± 1 °C) por 12 dias. Os resultados mostraram melhor conversão alimentar dos frangos que receberam dieta suplementada com 5g/kg. As coxas e sobrecoxas dos frangos que receberam folhas de oliveira apresentaram melhor estabilidade microbiológica que o controle, em que 5 g/kg inibiu o crescimento de Staphylococcus aureus, aeróbios psicrotróficos e mesófilos e 10 g/kg inibiu o crescimento de Enterococcus spp., bactérias ácido láticas, coliformes termotolerantes e totais, Pseudomonas, Clostridium perfringens e Escherichia coli (p < 0,05). Os resultados indicam a possibilidade de uso de folhas de oliveira, como suplemento alimentar, com vistas à melhoria da qualidade microbiológica da carne de frango.

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.

Effects of the dietary incorporation of olive leaves on growth performance, digestibility, blood parameters and meat quality of growing pigs

BACKGROUND

In a preliminary study the oxidative stability and tocopherol content of pork meat were shown to be improved by olive leaf (OL) feed supplementation at 50 and 100 g kg(-1) . However, growth performance was affected negatively. Therefore the objective of the present study was to assess the influence of OL supplementation at a lower level on feed digestibility, growth performance and meat quality.

RESULTS

Pigs were fed a basal diet (control), a basal diet with 25 g OL kg(-1) (OL2.5) or a basal diet with 50 g OL kg(-1) (OL5). The incorporation of OL significantly decreased growth rates (P = 0.010) and backfat thickness (P = 0.035) and increased feed/gain ratio (P = 0.032) in the OL5 group. Feed/gain ratio increased more for females (P = 0.001). The incorporation of OL decreased the crude fat (P = 0.006) and protein (P = 0.037) digestibility of both OL diets. Nevertheless, OL was effective in increasing the tocopherol content of meat (P = 0.009). However, meat from pigs fed the OL diets showed similar conjugated diene content, pH and colour parameters to that from pigs fed the control diet, even after 6 days of storage at 4 °C.

CONCLUSION

The data indicate that olive leaves may be included in pig diets at 25 g kg(-1) in order to improve the tocopherol content of meat without excessively compromising growth performance.

In vivo and in vitro addition of dried olive extract in poultry

A freeze-dried powder from organic olive (Olea europaea) juice extract, contains 8.82% polyphenols and a minimum of 2.5% hydroxytyrosol (3,4-dihydroxyphenylethanol), an effective free radical scavenger and the major antioxidant in the byproduct (dried olive extract, DOE). Myricetin, a bioflavonoid extract from the bark powder of the bayberry tree (Myrica cerifera), also has many beneficial biological properties and antioxidative capacity. While well-known as antioxidants, the capacity of these compounds to retard lipid oxidation in foods containing unsaturated fatty acids has not been widely evaluated. Thus, a study was conducted to assess the capacity of DOE to (1) enhance the growth of poultry, (2) determine the effectiveness of DOE (administered in vivo) as an antioxidant in post-mortem tissue and further processed meat, and (3) compare the in vitro antioxidative capacity of hydroxytyrosol and myricetin. DOE was administered ad libitum in water at 6 and 12 mg per bird per day for 6 weeks in a factorial design: 3 diets (control plus two treatment levels) × 2 blocks × 2 replications. There was no enhancement of feed consumption, body weight (BW), or feed conversion by DOE; overall means for these measurements were 5.49 kg per bird, 3.32 kg per bird, and 1.65 g feed per g live BW, respectively. Diagnostic examinations of two birds per pen at the end of the study revealed no adverse effects due to consumption of DOE, a generally recognized as safe substance. The byproduct, administered in vivo, did not retard lipid oxidation in fresh, heated, or NaCl (1.0% w/w)/heated/stored meat as assessed by absorbance values for thiobarbituric acid reactive substances at 532 nm and 2,2-diphenylpicrylhydrazyl at 517 nm. Both the byproduct and hydroxytyrosol are highly water-soluble and may have been unavailable as an antioxidant in the tissue of broilers that did not consume water for 4-6 h prior to processing. As an additive in processed thigh meat, 6 and 12 mg of DOE (2.5% hydroxytyrosol) per 3 mg of meat, although not as effective as myricetin (95% purity), reduced oxidation. Further assessment revealed that hydroxytyrosol from the DOE, added at (1)/38 the concentration of myricetin, was almost 50% as effective.

Olive leaves (Olea europaea L.) versus α-tocopheryl acetate as dietary supplements for enhancing the oxidative stability of eggs enriched with very-long-chain n-3 fatty acids

BACKGROUND

Ninety-six brown Lohmann laying hens were equally assigned into four groups with six replicates. Hens within the control group were given a corn/soybean-based diet supplemented with 30 g kg(-1) fish oil. Two other groups were given the same diet further supplemented with olive leaves at 5 (OL5) and 10 (OL10) g kg(-1) respectively, while the diet of the fourth group was supplemented with α-tocopheryl acetate (TOC) at 200 mg kg(-1). Eggs were analysed for lipid hydroperoxide and malondialdehyde (MDA) contents, fatty acid profile, α-tocopherol content and susceptibility to iron-induced lipid oxidation.

RESULTS

Neither OL nor TOC supplementation affected (P>0.05) the fatty acid composition. Dietary supplementation with OL10 or TOC reduced (P≤0.05) the lipid hydroperoxide content but exerted no (P>0.05) effect on the MDA content of fresh eggs compared with controls. Eggs submitted to iron-induced lipid oxidation from the OL5 group presented higher (P≤0.05) MDA levels than the control but lower (P≤0.05) than the OL10 group. Eggs from the TOC group presented lower (P≤0.05) MDA levels compared with all groups at all incubation time points.

CONCLUSION

The results of this study suggested that dietary supplementation with both OL10 and TOC could protect n-3 fatty acids in eggs from deterioration.

Effect of supplementation of the laying hen diet with olive leaves (Olea europea L.) on lipid oxidation and fatty acid profile of α-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 α-linolenic acid enriched eggs during refrigerated storage, and to compare this effect with α-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 α-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°C. 3. Results showed that olive leaves or α-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 α-tocopheryl acetate, which in turn showed decreased concentrations of lipid hydroperoxides and MDA.