Oxidative Quality of Acid Oils and Fatty Acid Distillates Used in Animal Feeding

Effect of feeding olive pomace acid oil on pork lipid composition, oxidative stability, colour, and sensory acceptance

One of the targets of the meat industry is to reduce production costs and to increase the sustainability of the food chain, which has driven the attention towards the use of by-products as feed ingredients. Acid oils are fat by-products coming from the chemical refining process of edible oils, with a high energy value and that are approved as feed ingredients in the European Union. However, meat producers are hesitant to utilise them due to their varying composition and the limited understanding of their impact on animal performance and meat quality. The objective of this study was to evaluate the effects of using olive pomace acid oil (OPAO) instead of its corresponding crude olive pomace oil (OPO) or crude palm oil (PO) in pig diets on lipid composition, lipid oxidation and quality of pork loin (longissimus dorsi), fresh and after commercial refrigerated storage for 8 days. The experimental design consisted of feeding pigs with four diets supplemented with a 5% of PO, OPO, OPAO or a blend (B) of PO and OPAO (50:50, w/w). Fresh and refrigerated pork loin samples were assessed for fatty acid profile; tocopherol (T) and tocotrienol (T3) composition; lipid oxidative stability with the ferrous oxidation-xylenol orange method; 2-thiobarbituric acid (TBA) value; volatile compounds; colour; and sensory acceptance. Results showed that refrigeration reduced the total T + T3 levels and increased the TBA values and the volatile compound concentrations. The refrigerated storage also affected the instrumental colour parameters (L*, a* and b*) but not the overall acceptance of pork. Regarding the diet, pork from OPAO diet showed a higher unsaturated-to-saturated fatty acid ratio than pork from PO and B diets. The lowest T + T3 concentration was found in OPO and OPAO fresh pork and in OPAO refrigerated pork. The oxidative stability of fresh pork was lower for OPAO than for PO diet, but no significant effect of the diet was observed for this parameter in refrigerated pork. The TBA values and volatile compound concentrations of fresh pork were not affected by the diet. After refrigeration, OPAO pork had the highest TBA value and volatile compound concentrations. In any case, colour and consumer acceptance of pork were not affected by diet. In conclusion, in order to upcycle acid oils in pig diets, and considering results on the lipid oxidative stability of pork, it would be preferable to add the OPAO used in this study blended with PO.

Effect of Feeding Olive Pomace Acid Oil on Dark Chicken Meat Lipid Composition, Oxidative Stability, Color, and Sensory Acceptance

This study evaluated the effect of using olive pomace acid oil (OPAO) instead of crude palm oil (PO) or refined olive pomace oil (ROPO) on lipid composition, lipid oxidation, and quality of chicken meat. Broiler chickens were fed diets with 6% of PO, ROPO, or OPAO, and deboned legs with skin were sampled. Fresh and refrigerated (commercial conditions; 7 days) chicken meat samples were assessed for fatty acid (FA) composition, tocopherol (T) and tocotrienol (T3) content, lipid oxidative stability, 2-thiobarbituric acid (TBA) values, volatile compounds, color, and sensory acceptance. Using ROPO and OPAO led to meat richer in monounsaturated FAs and OPAO to lower α-T levels compared to PO. Oxidative stability, TBA values, volatile compounds, and overall acceptance of meat were not affected by diet. Refrigeration increased TBA values and some volatile compounds' concentrations, but it did not decrease redness or consumers' overall acceptance. Therefore, the OPAO used was an adequate fat source for chicken diets at 6%, as it produced dark meat lower in saturated FAs than PO without affecting lipid oxidation or overall acceptance. According to this, upcycling OPAO as an energy source in chicken diets would be possible, which can contribute to the sustainability of the food chain.

Influence of free fatty acid content and degree of fat saturation on production performance, nutrient digestibility, and intestinal morphology of laying hens

This study was conducted to evaluate the effects of dietary free fatty acid (FFA) content and degree of fat saturation on production performance, lipid and calcium digestibility, and intestinal function of laying hens. For a 15-week period, a total of 144 laying hens (19 weeks old) were randomly assigned to 8 dietary treatments, which were obtained by gradually replacing crude soybean oil with soybean acid oil (AO), or crude palm oil with palm fatty acid distillate (FAD). Thus, there were 4 soybean and 4 palm diets with 6% added fat varying in their FFA percentage (10%, 20%, 30%, and 45%), following a 2 × 4 factorial design. Each treatment included 6 replicates with 3 birds per replicate. Average daily feed intake and final body weight were significantly higher in palm diets (P < 0.001), while no differences were found in egg mass and feed conversion ratio. Higher levels of FFA in soybean diets resulted in lower egg production and higher egg weight (linear, P < 0.01). Regarding the degree of fat saturation, hens fed soybean diets presented higher digestibility of ether extract (EE), fatty acids, and calcium than palm diets (P < 0.001). The dietary FFA percentage negatively affected the digestibility of EE and calcium (P < 0.01), while having little effect on FA digestibility. There was a significant interaction in the AME; lower values were reported in soybean diets as the dietary FFA percentage increased (linear, P < 0.01), whereas palm diets remained unaffected. The experimental diets had little effect on gastrointestinal weight and length. However, the jejunum of soybean diets showed higher villus height and higher villus height-to-crypt depth ratio than palm diets (P < 0.05), and the dietary FFA percentage increased the crypt depth and decreased the villus height-to-crypt depth ratio (linear, P < 0.05). It was concluded that varying dietary FFA content did not affect fat utilization as much as the degree of saturation did, supporting the use of AO and FAD as alternative fat ingredients.

Effect of Feeding Acid Oils on European Seabass Fillet Lipid Composition, Oxidative Stability, Color, and Sensory Acceptance

Acid oils (AO) are fat by-products of edible oil refining with a high energetic value, being an interesting option for a more sustainable aquaculture nutrition. This study was conducted to evaluate the effects of the partial replacement of fish oil (FO) in diets by two AO instead of crude vegetable oils on the lipid composition, lipid oxidation and quality of fresh European seabass fillets, and after their commercial refrigerated storage for 6 days. Fish were fed with five different diets, the added fat being FO (100%) or a blend of FO (25%) and another fat (75%): crude soybean oil (SO), soybean-sunflower acid oil (SAO), crude olive pomace oil (OPO), or olive pomace acid oil (OPAO). Fresh and refrigerated fillets were assessed for fatty acid profile, tocopherol (T) and tocotrienol (T3) composition, lipid oxidative stability, 2-thiobarbituric acid (TBA) value, volatile compound content, color, and sensory acceptance. Refrigerated storage did not affect T + T3 total content but increased secondary oxidation products (TBA values and volatile compound contents) in fillets from all diets. The FO substitution decreased EPA and DHA and increased T and T3 in fish fillets, but the recommended human daily intake of EPA plus DHA could still be covered with 100 g of fish fillets. Both a higher oxidative stability and a lower TBA value were found in SO, SAO, OPO, or OPAO fillets, obtaining the greatest oxidative stability in OPO and OPAO fillets. Sensory acceptance was not affected by the diet or the refrigerated storage, while the differences found in color parameters would not be perceived by the human eye. According to the oxidative stability and acceptability of flesh, SAO and OPAO are adequate replacements of FO as energy source in European seabass diets, which implies that these by-products can be upcycled, improving the environmental and economical sustainability of aquaculture production.

Influence of free fatty acid content and degree of fat saturation in laying hen diets on egg quality, yolk fatty acid profile, and cholesterol content

The aim of the present study was to evaluate the effect of dietary free fatty acid (FFA) content and the degree of saturation on egg quality, yolk fatty acid (FA) profile, and yolk cholesterol content. For a 15-wk period, a total of 144 laying hens (19-wk-old) were randomly assigned to 8 treatments arranged in a 2 × 4 factorial design, with 2 sources of crude oil (soybean oil and palm oil) and 4 levels of FFA (10, 20, 30, and 45%). The dietary treatments were achieved by progressively substituting the original oils with equivalent amounts of their corresponding acid oils (soybean acid oil and palm fatty acid distillate, respectively). No differences in ADFI or egg mass were found. However, dietary FFA reduced egg production (linear, P < 0.05) and increased the feed conversion ratio (linear, P < 0.05). Higher levels of FFA in soybean diets resulted in higher egg weight with higher albumen and yolk weights (linear, P < 0.01). Palm diets presented higher yolk:albumen ratio than soybean diets (P < 0.001), but the effect of FFA did not follow a linear trend. Hens fed soybean diets laid eggs with higher Haugh units (HU) than palm diets (P < 0.001), although increasing the dietary FFA% reduced the HU values in both (linear, P < 0.001). Palm diets enhanced shell quality with greater resistance to breakage, and higher dry matter and ash content than soybean diets (P < 0.05). No differences in egg chemical composition and yolk cholesterol content were found (P > 0.05). The saturation degree had a significant effect on all the analyzed yolk FA (P < 0.001) except for arachidonic acid (C20:4 n-6), whereas increasing the FFA content did not affect to a great extent. These results show that varying dietary FFA level did not affect egg quality and yolk composition as much as the dietary fat source did, supporting the use of acid oils and fatty acid distillates as fat ingredients for feed.