Volatile profiles and lipid oxidation of irradiated cooked chicken meat from laying hens fed diets containing conjugated linoleic acid

Effects of ionizing radiation on organic volatile compounds from PEA protein isolate

Food irradiation is a preservation technique and in respect with regulations, is applied to a limited number of products. Nevertheless, this technique could be interesting for products sensitive to heat treatment, and to limit alteration caused to their organoleptic characteristics. This study concerns the potential of ionization for vegetable proteins, to limit the damage on the sensory properties that can be caused by thermal treatments. The impact of β-ionizing was measured on the volatile compounds of five pea protein isolates. These isolates were subjected to ionizing radiation of 10 MeV electron beam and the volatile compounds were compared by SPME-GC-MS before and after the treatment. β-Ionization led to a major increase in the total amount of volatiles and to appearance of new compounds. We observed a strong increase in aldehydes, that were reported to be involved in pea off-flavor, and the appearance of dimethyl-disulfide, linked to sulfurous off-notes. Many of the compounds impacted by the treatment were linked to protein and lipid oxidations. Mechanisms explaining the impact of β-ionizing on lipids and protein oxidations were proposed.

Chicken fillets subjected to UV-C and pulsed UV light: Reduction of pathogenic and spoilage bacteria, and changes in sensory quality

We have compared the efficacy of continuous ultraviolet (UV-C) (254 nm) and pulsed UV light in reducing the viability of Salmonella Enteritidis, Listeria monocytogenes, Staphylococcus aureus, enterohemorrhagic Escherichia coli, Pseudomonas spp., Brochothrix thermospacta, Carnobacterium divergens, and extended-spectrum β-lactamase producing E. coli inoculated on chicken fillet surface. Fluences from 0.05 to 3.0 J/cm2 (10 mW/cm2, from 5 to 300 s) used for UV-C light resulted in average reductions from 1.1 to 2.8 log cfu/cm2. For pulsed UV light, fluences from 1.25 to 18.0 J/cm2 gave average reductions from 0.9 to 3.0 log cfu/cm2. A small change in the odor characterized as sunburnt and increased concentration of volatile compounds associated with burnt odor posed restrictions on the upper limit of UV treatment, however no sensory changes were observed after cooking the meat. Treatments under modified atmosphere conditions using a UV permeable top film gave similar or slightly lower bacterial reductions.

PRACTICAL APPLICATIONS

Ultraviolet (UV) light may be used for decontaminating the surface of food products and reduce viability of pathogenic and spoilage bacteria. Exposure of raw chicken fillet surface to various doses of continuous UV-C or pulsed UV light proposed in the present work represent alternatives for microbiological improvement of this product. Chicken fillets can be treated in intact packages covered with UV permeable top film, thus avoiding recontamination of the meat. UV-C light treatment is a low cost strategy with low maintenance, whereas pulsed UV light involves more elaborate equipment, but treatment times are short and less space is required. Both methods can be helpful for producers to manage the safety and quality of chicken fillets.

Nutrient Profiles and Volatile Odorous Compounds of Raw Milk After Exposure to Electron Beam Pasteurizing Doses

Raw milk is known to contain relatively high numbers of microorganisms, some of which include microbial pathogens. Electron beam (eBeam) processing is a nonthermal pasteurization food processing technology. The underlying hypothesis was that eBeam processing will not negatively influence the composition, nutrient content, and aroma profile of raw milk. Raw milk samples were exposed to eBeam doses of 1 and 2 kGy, since our studies had shown that 2 kGy is suitable for raw milk pasteurization. The untreated and eBeam-treated raw milk samples were analyzed to detect changes in lactose, vitamin B₂ , vitamin B₁₂ , and calcium concentrations. The possible breakdown of casein and whey proteins and lipid oxidation were investigated along with the formation of volatile aroma compounds. Even though vitamin B₂ showed a 31.6% decrease in concentration, the B₂ content in eBeam-pasteurized raw milk met all USDA nutritional guidelines. Even though there were no indications of lipid oxidation after the 2.0-kGy eBeam treatment, there was lipid oxidation (58%) after 7 d of refrigerated storage. However, based on the GC-olfactory analysis, the lipid oxidation did not necessarily result in the development of a wide variety of off-odors.

Antioxidant Activity of Brown Soybean Ethanolic Extracts and Application to Cooked Pork Patties

The brown soybean extract (BE, extracted by distilled water, 50%, 75%, and 95% ethanol) were analyzed for their total phenol, flavonoid, anthocyanin content, and DPPH radical-scavenging activity to determine antioxidant activities. Brown soybean extract with 75% ethanol showed significantly higher DPPH radical scavenging activity, total phenol and anthocyanin content compared to the other treatments (p<0.05). Then, brown soybean extract with 75% ethanol was applied to pork patties at different concentration (0.05%, 0.1%, and 0.2%) and lipid oxidation was evaluated during 15 d of refrigerated storage. Addition of BE significantly increased redness and pH values, respectively (p<0.05). Moreover, TBARS value of pork patties decreased significantly (p<0.05) as BE concentration increased. In sensory evaluation, pork patties with 0.1% BE had significantly higher score than other treatments in flavor and overall acceptability (p<0.05). Consequently, these results indicate that 0.1% BE could be an effective natural antioxidant to inhibit lipid oxidation in pork patties.

Comparison of fatty acid profile in the chicken meat after feeding with narasin, nicarbazin and salinomycin sodium and phyto-additive substances

The purpose of this study was an experimental investigation and a statistical evaluation of the influence of various additives in feed mixtures of broiler chickens on fatty acids content and their ratio in breast and thigh muscles. First feed additive consisted of narasin, nicarbasin and salinomycin sodium, and other five additives were of phytogenic origin. In vivo experiment was realized on the poultry experimental station with deep litter breeding system. A total of 300 one-day-old hybrid chickens Cobb 500 divided into six groups were used for the experiment. The experimental period was divided into four phases, i.e. Starter, Grower 1, Grower 2 and Final, according to the application of commercial feed mixture of soy cereal type. Additive substances used in feed mixtures were different for each group. Basic feed mixtures were equal for all groups. Fatty acid profile of breast and thigh muscles was measured by the method of FT IR Nicolet 6700. Investigated additive substances in the feed mixtures did not have statistically significant effect on fatty acid content and omega-6/omega-3 polyunsaturated fatty acid (PUFA) ratio in breast and thigh muscles. Strong statistically significant relation between omega-6 PUFAs and total PUFAs were proved by experiment. A relation between omega-3 PUFAs and total PUFAs was found only in the group with Biocitro additive.

The effects of conjugated linoleic acid on growth performance, carcass traits, meat quality, antioxidant capacity, and fatty acid composition of broilers fed corn dried distillers grains with solubles

This study investigated the effects of dietary supplementation with conjugated linoleic acid (CLA) on the growth performance, carcass traits, meat quality, antioxidant capacity, and fatty acid composition of broilers fed corn dried distillers grains with solubles (DDGS). Four hundred eighty 1-d-old broilers were randomly assigned to 4 groups, consisting of 6 replicates with 20 broilers each. Broilers were allocated 1 of 4 diets and fed for 49 d in a 2 × 2 factorial design. The dietary treatments consisted of 2 levels of DDGS (0 or 15%) and 2 levels of CLA (0 or 1%). The results of growth performance analyses showed that dietary supplementation with 1% CLA, 15% DDGS, or both in broilers had no significant effects on ADG, ADFI, and feed/gain (P > 0.05). Dietary supplementation with 15% DDGS did not significantly affect meat color values, drip loss percentage, pH value at 15 min, crude fat content, or shear force value (P > 0.05). Diets supplemented with 15% DDGS decreased the proportions of saturated fatty acids (P < 0.05) and monounsaturated fatty acids but increased the proportion of polyunsaturated fatty acids of the thigh meat (P < 0.05). Diets supplemented with 1% CLA significantly decreased the abdominal fat percentage (P < 0.05). Supplementation with 1% CLA increased the crude fat content and decreased the color (b*) value and shear force value of the breast meat (P < 0.05). Diets supplemented with 1% CLA increased the total superoxide dismutase activity of the serum, breast meat, and liver, and decreased the malondialdehyde content of the serum and breast meat (P < 0.05). Supplementation with 1% CLA decreased the proportion of monounsaturated fatty acids and increased the proportion of saturated fatty acids (P < 0.05). Accumulation of CLA in the thigh meat was significantly increased (P < 0.05) with increasing CLA level in the diet. In conclusion, dietary supplementation with 1% CLA had positive effects on meat quality, antioxidant capacity, and fatty acid composition of broilers, although it had no significant effect on growth performance.

Conjugated linoleic acid and betain prevent pork quality issues from diets containing distillers’ dried grains with solubles

Su, B., Wang, L., Wang, H., Shi, B., Shan, A. and Li, Y. 2013. Conjugated linoleic acid and betain prevent pork quality issues from diets containing distillers’ dried grains with solubles. Can. J. Anim. Sci. 93: 477–485. An experiment was conducted to evaluate the effects of conjugated linoleic acid (CLA) or betaine (BET) in diets containing distillers’ dried grains with solubles (DDGS) on the fatty acid profile and the shelf-life attributes of pork. Thirty-two (60±2 kg) crossed-bred barrows (Duroc×Landrace×Yorkshine) were randomly assigned to one of four diets: (1) the control diet containing no corn DDGS (control group); (2) the diet containing 30% corn DDGS (DDGS-fed group); (3) the diet containing 30% corn DDGS and 10 g kg−1 CLA (CLA-fed group); (4) the diet containing 30% corn DDGS and 1 g kg−1 BET (BET-fed group). Dietary DDGS decreased the proportion of saturated fatty acids (SFA) (P<0.05), and increased the proportion of unsaturated fatty acids (UFA) and polyunsaturated fatty acids (PUFA) (P<0.05) in pork with respect to the control group, whereas dietary CLA and BET decreased the proportion of PUFA and increased the proportion of SFA in pork compared with DDGS-fed group. Pork treated with DDGS alone had higher total volatile basic nitrogen (TVB-N) value (P<0.05) and thiobarbituric acid reactive substances (TBARS) value (P<0.05) with respect to the control diet during display, whereas CLA-fed group and BET-fed group had lower TVB-N concentration and TBARS value (P<0.05) in pork than DDGS-fed group. There was no significant difference of instrumental color (L*, a*, b*) between DDGS-fed group and the control group (P>0.05). However, CLA-fed and BET-fed groups maintained lower L* values and higher a* values (P<0.05), but did not affect b* values with respect to the DDGS-fed group and the control group. Results confirmed that diets containing 30% DDGS have some adverse effects on pork freshness and lipid peroxidation; However, supplementation with CLA or BET can partially reverse these effects and improve color image of pork during display.

Elevation of tissue α-tocopherol levels by conjugated linoleic acid in C57BL/6J mice is not associated with changes in vitamin E absorption or α-carboxyethyl hydroxychroman production

OBJECTIVE

Conjugated linoleic acid (CLA) decreases adipose mass and increases vitamin E levels in the liver and adipose tissue in mice. The aim of the present study was to examine the mechanism by which CLA alters vitamin E levels in tissues and antioxidant activity in mice.

METHODS

C57BL/6J mice were divided into three groups and fed 5% lipid as soybean oil alone (control group), 4% soybean oil supplemented with 1% CLA (CLA group), or 5% lipid with a vitamin E supplement (VE group) for 4 wk.

RESULTS

The CLA and VE diets resulted in a significant increase in the α-tocopherol concentration in all tissues examined, i.e., the liver, kidney, testis, spleen, heart, lung, and adipose tissue (P < 0.05). Levels of thiobarbituric acid-reactive substances in the kidney, testis, heart, lung, and adipose tissue were lower in the CLA and VE groups than in the control group (P < 0.05). CLA did not alter the absorption rate of vitamin E or α-carboxyethyl hydroxychromans levels in the liver and plasma. The CLA diet induced a significant increase in α-tocopherol transfer protein and mRNA levels in the liver. CLA resulted in a decrease in catalase and glutathione peroxidase activities and peroxisome proliferator α mRNA levels but had no effect on levels of mRNAs for other nuclear transcription factors in the liver.

CONCLUSION

The increase in vitamin E status in CLA-fed mice is not due to altered absorption and metabolism of vitamin E but might be related to the induction of α-tocopherol transfer protein expression in the liver. The regulation of the activities of catalase and glutathione peroxidase by CLA is not mediated by vitamin E accumulation in the liver.

Effect of conjugated linoleic acid on growth performances, carcase composition, plasma lipoprotein lipase activity and meat traits of chickens

1. The effects of dietary conjugated linoleic acid isomers (CLAs) on productive traits, carcase yield and meat quality were investigated in Beijingyou (Chinese) chickens. A total of 360 male chicks were allocated to 5 dietary treatments (0.00, 0.25, 0.50, 1.00 and 2.00% CLA) and fed for 126 d. 2. The results showed that CLA supplementation did not significantly influence body weight, but increased feed conversion and decreased intramuscular fat in breast and thigh muscles. Mortality was significantly higher in the control group. 3. The addition of 1.0 and 2.0% CLA decreased abdominal fat percentages. At CLA dietary levels greater than 0.5%, lipoprotein lipase activity in plasma was significantly decreased. 4. Hunter L* and a* values were not significantly affected by CLA supplementation. However, Hunter b* values were lower in chickens supplemented at levels greater than 0.5% CLA. Supplementing diets with CLA modified the fatty acid composition of breast muscle. The proportions of CLA, saturated and polyunsaturated fatty acids were increased whereas the proportion of monounsaturated fatty acids was decreased.

Impact of irradiation on the safety and quality of poultry and meat products: a review

For more than 100 years research on food irradiation has demonstrated that radiation will make food safer and improve the shelf life of irradiated foods. Using the current food safety technology, we may have reached the point of diminishing returns even though recent figures from the CDC show a significant drop in the number of foodborne illnesses. However, too many people continue to get sick and die from eating contaminated food. New and under utilized technologies such as food irradiation need to be re-examined to achieve new levels of safety for the food supply. Effects of irradiation on the safety and quality of meat and poultry are discussed. Irradiation control of the principle microbial pathogens including viruses, the differences among at-risk sub-populations, factors affecting the diminished rate of improvement in food safety and published D values for irradiating raw meat and poultry are presented. Currently permitted levels of irradiation are probably not sufficient to control pathogenic viruses. Typical gram-negative spoilage organisms are very sensitive to irradiation. Their destruction leads to a significant increase in the acceptable shelf life. In addition, the destruction of these normal spoilage organisms did not provide a competitive growth advantage for irradiation injured food pathogens. Another of the main focuses of this review is a detailed compilation of the effects of most of the food additives that have been proposed to minimize the negative quality effect of irradiation. Most of the antimicrobials and antioxidants used singly or in combination produced an increased lethality of irradiation and a decrease in oxidation by-products. Combinations of dosage, temperature, dietary and direct additives, storage temperature and packaging atmosphere can produce meats that the average consumer will find indistinguishable from non-irradiated meats. A discussion of the production of unique radiological by-products is also included.

Effect of dietary conjugated linoleic acid on body composition and energy balance in broiler chickens

The effect of dietary conjugated linoleic acid (CLA) on body composition and energy metabolism was investigated in broiler chickens. Male broiler chicks were assigned to receive either a control diet (1 % sunflower oil) or a diet containing CLA (1 % of a 1:1 mixture oftrans-10,cis-12 andcis-9,trans-11 isomers of octadecadienoic acid). The diets were fedad libitumfor 3 weeks and there were eight replicates per diet, each replicate including four chickens so that each treatment had thirty-two animals. The proportion of body fat was lower in the control group than in the CLA group. No significant differences as to the proportions of body water, ash and protein were observed. Feed and energy intake were significantly lower in CLA-fed birds. The percentage of ingested energy lost in excreta was higher after CLA feeding and heat expenditure as a percentage of ingested energy was lower in the CLA-fed group. The CLA-fed group showed a higher percentage of SFA and lower percentages of MUFA and PUFA in carcass fat. It is concluded that CLA stimulatedde novofatty acid synthesis and lowered desaturase activity.

Thiobarbituric Acid Reactive Substances and Volatile Compounds in Chicken Breast Meat Infused with Plant Extracts and Subjected to Electron Beam Irradiation

The effect of irradiation on thiobarbituric acid reactive substances (TBARS) and volatile compounds in raw and cooked nonirradiated and irradiated chicken breast meat infused with green tea and grape seed extracts was investigated. Chicken breast meat was vacuum infused with green tea extract (3,000 ppm), grape seed extract (3,000 ppm), or their combination (at a total of 6,000 ppm), irradiated with an electron beam, and stored at 5 degrees C for 12 d. The targeted irradiation dosage was 3.0 kGy and the average absorbed dosage was 3.12 kGy. Values of TBARS and volatile compound contents of raw and cooked chicken meat were determined during the 12-d storage period. Thiobarbituric acid reactive substances values ranged from 15.5 to 71.4 mg of malondialdehyde/kg for nonirradiated raw chicken and 17.3 to 80.1 mg of malondialdehyde/kg for irradiated raw chicken. Values for cooked chicken ranged from 31.4 to 386.2 and 38.4 to 504.1 mg of malondialdehyde/kg for nonirradiated and irradiated chicken, respectively. Irradiation increased TBARS and hexanal values of controls and meat infused with plant extracts. Hexanal had the highest intensity of volatiles followed by pentanal and other volatiles. Cooking the samples significantly (P < 0.05) increased the amounts of TBARS and volatiles. Addition of plant extracts decreased the amount of TBARS as well as hexanal and pentanal values. Although irradiation increases lipid oxidation, infusion of chicken meat with plant extracts could reduce lipid oxidation caused by irradiation.

Dietary conjugated linoleic acid alters hepatic lipid content and fatty acid composition in broiler chickens

We examined the effect of dietary conjugated linoleic acid (CLA) on growth performance and liver composition in broiler chickens. Day-old male broiler chicks were assigned to receive a diet supplemented with corn oil (5%; n = 48) or CLA (5%; n = 48) for 21 d. Broilers fed CLA weighed less and grew at slower rates than broilers fed corn oil. Feed intake and feed conversion were higher for the corn-oil group than for the CLA dietary group. Hepatic lipid and triacylglycerol concentrations were significantly reduced by dietary CLA. The proportions of saturated fatty acids (SFA) in liver lipids increased, whereas those of monounsaturated fatty acids (MUFA) decreased with CLA supplementation. Although the total concentration of polyunsaturated fatty acids (PUFA) did not change with dietary treatment, the concentration of linoleic acid as a percentage of total methylated fatty acids decreased, and that of linolenic add increased in broilers fed CLA. The concentration of CLA isomers in liver lipids increased substantially with CLA feeding. The relative proportion of the c9,t11 CLA isomer in hepatic lipids was much higher than that of the t10,c12 or t9,t11 CLA isomers. These studies provide evidence that feeding CLA to broilers results in substantial reduction in liver fat accumulation and promotes CLA incorporation into hepatic lipid pools.

Quality characteristics of irradiated ready-to-eat breast rolls from turkeys fed conjugated linoleic acid

The objective of this study was to determine the effect of irradiation on the quality of ready-to-eat (RTE) breast rolls from turkeys fed conjugated linoleic acid (CLA). The oxidative stability of RTE turkey rolls was improved by the dietary CLA treatment. Irradiation increased the production of acetaldehyde, 3-methyl-butanal, 2-methyl-butanal, and total volatiles in turkey rolls but had little effect on other aldehydes. Irradiation also produced new volatiles, including sulfur compounds, not detected in nonirradiated turkey breast rolls. We detected significantly higher amounts of alkanes with nine or higher carbons in irradiated samples than in nonirradiated samples. Irradiation increased the redness of RTE turkey breast rolls, but the degree of redness and the amount of total volatiles decreased with storage. CLA treatment lowered the redness (a*) and increased the lightness (L*) of RTE turkey breast rolls during the entire storage period. Sensory evaluation revealed that irradiation produced off-flavor, but CLA and irradiation did not influence the texture and juiciness of RTE turkey breast rolls. Consumers did not like the off-flavor but preferred the color induced by irradiation to nonirradiated RTE turkey breast rolls.

Effect of dietary conjugated linoleic acid on the growth rate of live birds and on the abdominal fat content and quality of broiler meat

Two experiments were conducted to investigate the influence of dietary conjugated linoleic acid (CLA) on the growth, body composition, abdominal fat accumulation, and meat quality in broilers. In Experiment 1, 50 broilers that were 3 wk old (total of 200 birds) were assigned to one of the four diets containing 0, 0.25, 0.5, or 1% CLA and were fed for 3 wk. In Experiment 2, 40 broilers that were 3 wk old (total of 120 birds) were assigned to one of the three diets containing 0, 2, or 3% CLA and fed for 5 wk. At the end of the 3-wk feeding trial, the average body weight of broilers for Experiment 1 was about 2.20 kg per bird for all treatments. For Experiment 2, after 5-wk feeding trial, the average body weights of birds were 4.04, 3.99, and 3.93 kg for the control, 2% CLA, and 3% CLA groups, respectively, with a non significant reduction in body weight as the levels of dietary CLA increased. There was no difference in abdominal fat weight, the total body fat, and protein content in broilers among the CLA treatments for Experiment 1. However, when the dietary CLA was increased to 2 or 3%, the total body fat content was reduced. The whole body fat content decreased from 14.2% in the control to 11.9 and 12.2% for 2 and 3% CLA, respectively. Dietary CLA at 2 and 3% levels influenced meat quality. After cooking, the breast meat from 2 or 3% dietary CLA treatment was harder and drier, and the color was a little darker than that of the control. These changes could be caused by the decreased unsaturated fatty acid content in meat after CLA feeding, which increased the melting point of the fat.