INFLUENCE OF FEED FAT SOURCE ON FATTY ACID COMPOSITION, UNSATURATION AND LIPID OXIDATION OF BACKFAT AND SENSORY QUALITY OF PORK

The effect of different fats in a 9% fishmeal feed on backfat fatty acid composition, oxidation and pork sensory attributes was studied. The hydrogenated fish oil group (HFO) had significantly increased uptake of certain fatty acids in contrast to the other groups. Iodine values were highest in the fish oil group, followed by the lamb tallow group (LT) with the control group, containing no added fat, tailing. Backfat from the HFO group had more polyunsaturated fatty acids compared to the other groups and stearic/linoleic acid ratio suggested more oxidative problems with this group. The HFO group led the LT group in oxidation with the control group being most stable. Sensory traits of fresh and frozen pork chops correlated with the oxidation results. Fat from pigs fed hydrogenated fish oil in their diet are therefore more susceptible towards oxidation possibly due to more polyunsaturated fatty acids and oxidation products in the backfat.     

INFLUENCE OF LOW FAT FISHMEAL ON FATTY ACID COMPOSITION AND SENSORY QUALITY OF PORK

Four groups of growing-finishing pigs, were fed low fat fishmeal together with an increased level of fish oil. Additional fish oil increased the content of long-chain n-3 fatty acids in subcutaneous fat and muscle when feeding up to 9 g fish oil kg^-1 diet. Sensory quality of fresh meat was not affected by the increased level of fish oil in diets but the intensity of off-flavor/odor and rancid flavor/odor of fat increased after six months of frozen storage. Partial least square regression of rancid flavor/odor after six months of frozen storage using the significant variables C20:1, C20:5 (EPA), C22:5 (DPA) and C22:6 (DHA) in subcutaneous fat gave correlation coefficients as high as 0.92. Based on these results, the use of low fat fishmeal is acceptable but the content of fish oil should be limited to 3 g fish oil kg^-1 diet for growing-finishing pigs.     

Influence of fishmeal, rape-seed, and rape-seed meal in feed on the fatty acid composition and storage stability of porcine body fat

One hundred and ten pigs were fed test diets containing 1·1%, 3·3% or 5·5% fishmeal, 10% rape-seed or 15% rape-seed meal. The control diet contained soya-bean meal. From each carcass M. longissimus dorsi, including subcutaneous fat, was taken and analysed for fatty acid composition and intramuscular fat content. Accelerated oxidation test was carried out on fresh samples. Sensory analyses as well as peroxide and aldehyde analyses were carried out after 0, 4, 6 and 9 months of freezer storage. The sensory properties of fresh meat and fat were not affected by any of the feed components tested. After 6 months of freezer storage slightly increased levels of off-flavours were noted with 3% fishmeal or more in the diet. Also, the peroxide value after storage increased at the same fishmeal level. With rape-seed or rape-seed meal in the diet the scores for off-flavours increased only slightly. A much lower storage stability was noted in fat from pigs fed a combination of rape-seed and fishmeal. Extra vitamin E in diets did not increase the storage stability of pork fat. Special attention was paid to the incorporation of dietary polyunsaturated fatty acids (PUFA), especially marine-PUFA, into body fat. It was found that the incorporation of C22:6 was a very good indicator of the amount of fishmeal in the diet.     

Prooxidant effects of the combination of green tea extract and sodium nitrite for accelerating lipolysis and lipid oxidation in pepperoni during storage

Abstract: The individual and interactive effects of green tea (GT) extract and sodium nitrite (NT) on lipolysis and lipid oxidation were investigated in pepperoni during processing and storage (4 °C). Pepperoni was treated with GT at concentrations of 0.02%, 0.05%, 0.1%, 0.2%, 0.5%; and NT from 0.003% to 0.015% in increments of 0.003%; and a combination of 0.05% GT and 0.009% NT (GT/NT). The pH, color, residual nitrite, fatty acid (FA), and 2‐thiobarbituric acid reactive substances (TBARS) values were measured. The results showed inhibitory effects on TBARS value were concentration dependent. The largest effect was at 0.05% for GT and 0.009% for NT. Adding 0.05% GT significantly decreased (P < 0.05) the TBARS values but did not affect color values during storage. NT (0.009%) was more effective than GT (0.05%) for maintaining lower TBARS values (P < 0.05). Total fatty acids were not affected by 0.05% GT and 0.009% NT treatments. However, adding GT/NT showed a significant prooxidant effect (P < 0.05) in pepperoni, which accelerated lipolysis and lipid oxidation significantly (P < 0.05) during storage, with depletion of nitrite. This suggests that adding GT and an appropriate amount of NT into pepperoni could promote lipolysis and lipid oxidation during storage, as compared to NT alone. Practical Application: When using GT extract as an antioxidant in industrial production of pepperoni, the interaction effect with NT should be considered, as it may lead to a prooxidant effect during refrigerated storage.     

INCLUDING CHESTNUTS AND SUGAR BEET PULP IN DIETS FOR PIGS: THE EFFECTS ON THE QUALITY OF PORK MEAT AND THE SENSORY PROPERTIES OF DRY-CURED SAUSAGE (CHORIZO GALLEGO)

This research was aimed at evaluating how the inclusion of dried chestnuts and dried sugar beet pulp in diets for pigs affected the quality of pork meat and the sensory properties of dry-cured sausage ( chorizo gallego ). The meat from pigs that received a diet with chestnuts and sugar beet pulp (CBP) showed lower thiobarbituric acid values and higher water-holding capacity than meat from pigs fed a conventional diet (C). Significant differences were also observed between both batches in color parameters and fatty acid composition of the meat. In the sensory analysis of chorizo, the sausages manufactured with meat from pigs fed the CBP diet were significantly better rated than those with meat from pigs fed a C diet in appearance, odor, flavor, texture and overall score.

PRACTICAL APPLICATIONS

The inclusion of dried chestnuts and dried sugar beet pulp in diets for pigs during the fattening period allowed us to recover some of the ingredients more traditionally used in the feeding of pigs. This inclusion modifies some parameters of the resulting pork meat quality; (it decreases lipid oxidation and increases water-holding capacity and polyunsaturated fatty acid content) and also improves the sensory properties of any dry-cured product made with this pork meat.     

Porcine Somatotropin (PST) Administration to Growing Pigs: Effects on Adipose Tissue Composition and Processed Product Characteristics

Fatty acid profiles and proximate composition were determined at seven carcass locations from 64 pigs. Fatty acid composition was not altered by PST treatment (P > 0.05). The more unsaturated outer layer of subcutaneous fat was present in a greater proportion in the PST-treated pigs. Adipose tissue fat content was decreased (P < 0.01), whereas percentage moisture and protein was increased (P < 0.01), by PST. Boneless ham characteristics did not differ among treatment groups (P < 0.05). Pepperoni from PST pigs dried more efficiently and was harder than control pepperoni. Bacon from PST pigs contained less fat and was softer than control bacon. Difference in texture of products, particularly bellies for bacon from PST-treated pigs, seemed to be a result of an altered proximate composition.     

STORAGE STABILITY OF COMMERCIALLY PREPARED AND FROZEN POND-RAISED CHANNEL CATFISH (Ictalurus punctauts, rafinisque)

SUMMARY –The storage stability of frozen pond-raised channel catfish from five commercial processing plants was examined. Three distinct types of processing treatment were included in the five lots. Fish samples were evaluated initially and at regular intervals during frozen storage up to 270 days. The evaluations included changes in moisture, pH, fat stability (TBA value) and shear press values of the uncooked fish, and in sensory ratings for appearance, aroma, color, texture and flavor of the cooked products. Moisture losses and changes in pH during frozen storage were not statistically significant (P = 0.05). Thiobarbituric acid (TBA) values indicative of changes in fat stability, incresed in all five lots of fish with prolonged storage but were not closely correlated with changes in flavor rating. Sensory ratings for quality of the cooked product decreased significantly with successive storage periods. The regression patterns representing changes in quality during storage varied among the different losts of fish. Certain variations were related to the processing treatments.     

Effect of dietary fish oil on fatty acid composition, lipid oxidation and sensory property of chicken frankfurters during storage

Broilers fed with three levels of fish oil (0, 2 and 4%) for 6 weeks were used in the manufacture of chicken frankfurters. The meat samples were vacuum-packed and stored at 0°C for 0, 10, 20 and 30 days. Cooking yield, proximate and fatty acid composition, lipid oxidation, microbial and sensory properties of the meat products were measured. Cooking yield, moisture, fat, protein, ash and cholesterol contents of frankfurters were not affected (P>0.05) by levels of dietary fish oil. Frankfurters processed from chickens fed diets enriched with 2 and 4% of supplemental fish oil had a higher (P<0.05) level of n-3 fatty acids (eicosapentaenoic acid and docosahexaenoic acid), but had a lower level of n-6 fatty acids (P<0.05) than the controls (0% fish oil). TBA values and pH values of meat samples were not affected (P>0.05) by levels of supplemental fish oil in the diets, however, pH values of the vacuum-packaged chicken frankfurters decreased (P<0.05) as the storage time increased. No differences (P>0.05) in total anaerobic plate counts were observed among the fish oil treatments during storage. Supplementation of 2 and 4% fish oil in the diets did not increase (P>0.05) the intensity of fishy flavor in chicken frankfurters.     

Effect of fat level and ripening temperature on biochemical and sensory characteristics of naturally fermented Turkish sausages (sucuk)

Changes in chemical and sensory characteristics of naturally fermented Turkish sausages during ripening were evaluated for three fat levels (10, 20 and 30%) and two different ripening temperatures, i.e. 20–22 and 24–26 °C. Fat level, ripening temperature and time affected total acidity, free fatty acids (FFA) and thiobarbituric acid (TBA) values. Both higher fat content and higher temperature resulted in higher FFA and TBA values during ripening, indicating high lipolytic and oxidative activity. TBA values showed an increase from the first to the ninth day, but were lower at 20–22 °C than at 24–26 °C. High fat level and temperature adversely affected rancid flavor and overall acceptability.     

Functional Characteristics, Fatty Acid Composition, and Palatability of Bacon from Pigs Fed Canola

Thirty-six pigs were fed diets containing 20% intact canola (IC), 20% ground canola (GC) or 0% canola (C). Processing yields and proximate composition of bacon were not affected by diet. Bacon from pigs fed GC had less saturated fatty acids and more monounsaturated fatty acids than bacon from pigs fed the IC or C diets. Bacon from pigs fed the C diet had less polyunsaturated fatty acids than bacon from pigs fed the IC or GC diets. Palatability of bacon from C, IC or GC treatments after 0 or 4 weeks storage was not different. After 8 weeks of storage, panelists tended to prefer control bacon over bacon from pigs fed the GC diet. Bacon from pigs fed the GC diet had higher 2-thiobarbituric acid values than bacon from pigs fed the IC or C diets.     

Effect of restricted feeding and realimentation periods on pork quality and fatty acid profile of M. longissimus thoracis

An experiment with 94 fattening pigs (48 gilts and 46 barrows) was conducted to determine the effect of feeding 25% restricted diets at different body weights on meat quality and fatty acid profile of M. longissimus thoracis (LT). During the 84 days of the experiment (4 periods, 21 days each), animals with an initial weight of about 31 kg were fed in different periods of observation ad libitum (A) or restricted diets (R) in groups AAAA, AARA, RAAA and RARA. After 21 days of the experiment, the restricted-fed pigs, compared to those fed ad libitum, had a lower total fat content of M. longissimus thoracis (P<0.05), higher shear force (P=0.068), and lower proportions of SFA (C14:0, C18:0 P<0.05) and MUFA and higher proportions of PUFA (C20:4, C22:4 P<0.05) in the fatty acid profile. Three weeks after the restricted feed supply was lifted, the total fat content in LT muscle was higher than in animals fed ad libitum throughout (2.34 vs. 2.02), very close after the next 3 weeks of realimentation (3.16 vs. 3.15) and lower after another 3 weeks (3.19 vs. 3.49). Regardless of the time at which restricted feeding was started and the number of restricted feeding periods, the total fat content in the LT muscle at the end of the experiment was similar or lower in groups RAAA, AARA and RARA, compared to group AAAA. The coefficient of correlation between the total fat content in LT and the shear force was -0.36 (P<0.01). Colour, pH and drip loss did not depend on the level of nutrition. After 84 days of observation, animals from groups RARA and AARA, compared to pigs from groups AAAA and RAAA, were characterized by a slightly higher shear force of LT, lower SFA and MUFA (P<0.001), and higher n-6 PUFA (P<0.01) and n-3 PUFA (P<0.01) proportions in the fatty acid profile. The fatty acid profiles of AAAA pigs and pigs undergoing a 63-day realimentation period (RAAA) were similar. Regardless of the feeding scheme, the n-6:n-3 ratio exceeded 10 in all the groups.     

泡酒肥肉浸制过程中脂肪氧化和脂肪酸组成的变化

泡酒肥肉是豉香型白酒(玉冰烧)生产过程"陈肉酝浸"工序中的关键元素,目前对泡酒肥肉在浸制过程中的变化尚不清楚。检测了泡酒肥肉浸制过程中的各阶段肥肉的脂肪氧化及脂肪酸含量的变化。结果表明,在浸制过程中,泡酒肥肉的酸价和硫代巴比妥酸值(TBARS)显著上升(p<0.05),总饱和脂肪酸(SFA)和总不饱和脂肪酸(UFA)含量均显著下降(p<0.05)。浸制后肥肉中的棕榈酸(C_16:0)、油酸(C_18:1)、硬脂酸(C_18:0)和亚油酸(C_18:2)等脂肪酸含量较高,且变化均显著(p<0.05);总饱和脂肪酸与总不饱和脂肪酸的比值(SFA/UFA)从1.83下降到1.38,变化显著(p<0.05),说明不饱和脂肪酸的比例升高,有利于后续豉香型白酒的陈肉酝浸过程中风味物质的生成。结果表明了泡酒肥肉浸制过程中脂肪氧化及脂肪酸的变化,将为建立泡酒肥肉质量标准提供科学依据。     

Oxidative stability of buttermilk as influenced by the fatty acid composition of cows' milk manipulated by diet

Milk from cows fed a low-fat diet high in cereals designed to stimulate fat synthesis de novo was lower in unsaturated fatty acids (21.3%) than milk from cows fed a diet high in fat, mainly from roasted soy beans (41.3% unsaturated fatty acids). Buttermilk from the more unsaturated milk was less oxidatively stable during storage (at 4 degrees C, followed for 11 d) than buttermilk from the more saturated milk, as monitored both by primary lipid oxidation products (lipid hydroperoxides) and by the secondary lipid oxidation product, hexanal. Fat-soluble antioxidants, beta-carotene and alpha-tocopherol, analysed by HPLC, were not consumed during storage for either of the two types of buttermilk. In contrast, the antioxidative capacity of the serum phase decreased during storage as evaluated in a radical scavenging assay based on the semi-stable water-soluble radical nitrosodisulphonate (Fremy's salt). The time course for the decrease in water-soluble antioxidants was very similar for the two types of buttermilk suggesting that oxidation is initiated in the serum phase independently of fatty acid composition.     

猪五花肉红烧过程中脂肪和脂肪酸的变化规律

目的：探讨以猪五花肉为原料的红烧肉加工过程中脂肪和脂肪酸的变化,以期对红烧肉的风味、营养、质地等研究提供参考。方法：对红烧肉加工过程中原料、油炸、炖煮过程样品（0～2 h,每30 min取样）以及成品的粗脂肪含量、过氧化值（peroxide value,POV）、硫代巴比妥酸（thiobarbituric acid reactive substances,TBARS）值以及脂肪酸含量进行测定。结果：五花肉红烧过程中脂肪含量显著下降（P＜0.05）,成品红烧肉脂肪含量比原料肉下降12.14%;POV先增大后减小,在炖煮30 min达到最大值;TBARS值逐渐增大,在炖煮过程中变化显著（P＜0.05）;油酸、棕榈酸、亚油酸和硬脂酸是五花肉脂肪中的主要脂肪酸,在红烧过程中饱和脂肪酸（saturatedfatty acid,SFA）含量变化不大（P＞0.05）,单不饱和脂肪酸（monounsaturated fatty acid,MUFA）含量显著上升（P＜0.05）,多不饱和脂肪酸（polyunsaturated fatty acid,PUFA）含量显著下降。结论：五花肉红烧过程中脂肪含量下降、脂肪发生适度氧化、脂肪酸组分构成发生了改变。     

Relationships among dietary roasted soybeans, milk components, and spontaneous oxidized flavor of milk.

Relationships among dietary roasted whole soybeans (RSB), milk fatty acid profile, and the development of spontaneous oxidized flavor of milk were investigated by using 20 commercial dairy herds. Diets contained 0 to 15.3% of dry matter as RSB. Concentrations of dietary RSB were correlated positively with concentrations of C18:2 and C18:3 in milk fat. Concentrations of alpha-tocopherol, beta-carotene, and ascorbic acid in milk decreased from 0 to 3 d of storage (4 degrees C), and oxidized flavor in milk increased linearly between 0 and 8 d of storage. Milk fatty acid profile did not change during storage. The development of oxidized flavor at 8 d postsampling was correlated (r) with increased concentrations in milk fat of C18:2 (0.49), C18:3 (0.55), total polyunsaturated milk fatty acids (0.50), and dietary concentrations of RSB (0.38). Multiple regression was used to quantify relationships between variables and oxidized flavor (samples stored 8 d). All significant models included milk concentrations of Cu and dehydroascorbic acid. Concentrations of C18:2, C18:3, or total polyunsaturated fatty acids in milk fat, or dietary RSB concentrations, and interactions of those variables with Cu were included in individual models. Milk with high concentrations of polyunsaturated fatty acids and Cu were most susceptible to oxidation. Feeding RSB increased polyunsaturated fatty acid concentrations in milk fat, which increased the likelihood of oxidized flavor, especially when milk had high concentrations of Cu.     

Lipid Composition and Flavor Changes in Irradiated Mango (var. Alphonso)

Changes were studied in fatty acid composition of the pulp, aroma and flavor of gamma irradiated (0.25kGy) and control mature green Alphonso mangoes during ripening at 25–30°C. Ripening of both control and irradiated mangoes was accompanied by changes in glycerides as well as fatty acids. Oleic acid of pulp oil of irradiated mangoes decreased appreciably during ripening as compared with controls. Lin-oleic acid of pulp oil of unirradiated fruits decreased markedly on the 6th day of storage. With irradiated fruits linoleic acid remained unaffected up to the 12th day of storage. Linolenic acid content of pulp oil of irradiated fruit increased much more than that of unirradiated fruit during ripening. Gas chromatographic profiles of volatiles of control and irradiated mangoes showed no difference.     

Effects of feeding elevated concentrations of monounsaturated fatty acids and vitamin E to swine on characteristics of dry cured hams

Thirty Large White×Great York gilts were fed six experimental diets containing three levels of poly and monounsaturated fatty acids. Within each dietary fat treatment, one group was fed a basal level of vitamin E (20 mg α-tocopheryl acetate/kg diet) and the other group received a supplemented level (200 mg α-tocopheryl acetate/kg diet). Concentration of α-tocopherol was significantly higher in hams from pigs fed supplemented dietary levels of vitamin E (P<0.0001), but no significant effect of dietary fat was observed. Dietary vitamin E supplementation reduced the concentration of thiobarbituric acid reactive substances after 9 days storage of sliced samples (P<0.0001), while dietary fat source showed no significant effect. Significantly lower oxidation was observed in ham homogenates from pigs fed higher concentrations of monounsaturated fatty acids after 120 min of incubation under pro-oxidant conditions (P=0.013). No effect of dietary treatment was observed in ham volatile aldehyde profile. No significant effect of dietary vitamin E was observed on surface redness during storage, but a significant effect was observed for luminosity after 7 days of storage (P=0.033). Hams from pigs fed diets enriched in monounsaturated fatty acid showed higher ‘a’ values (P=0.040) in stored sliced samples. Sensory evaluation revealed a significant effect of dietary vitamin E on redness of ham slices (P<0.001). Dietary supplementation with vitamin E also produced a significantly higher odour and flavour intensity (P=0.006 and P=0.01 respectively). Dry cured ham samples from pigs fed higher amounts of monounsaturated fatty acids showed a significantly higher consistency fat than those from pigs fed polyunsaturated fatty acids.     

Maternal dietary fat affects the LT muscle fatty acid composition of progeny at weaning and finishing stages in pigs

The present study was conducted to investigate whether maternal dietary fat affects the fatty acid composition of the longissimus thoracis (LT) muscle in offspring pigs at weaning and finishing stages. Fourteen sows were randomly assigned to a control or a high fat (HF) group. The HF sows received a diet containing 8% corn oil starting seven days before farrowing until weaning. The results showed that a high-fat diet significantly increased the contents of serum-lipid-related indexes in the sows. Although the triglyceride content did not change, the C18:2n − 6 content was higher in the colostrum and in the LT muscle of offspring pigs at both investigated stages. The total n − 6 content and the n − 6/n − 3 ratio generally increased. This study demonstrated that maternal dietary fat during lactation affects the fatty acid composition of the LT muscle of progeny at weaning, and can have persistent effects in later life.     

Influence of the in vivo addition of alpha-tocopheryl acetate with three lipid sources on the lipid oxidation and fatty acid composition of Beluga sturgeon, Huso huso, during frozen storage

This study was conducted to investigate the effect of dietary alpha-tocopheryl acetate (vitamin E) and oil sources on fish flesh quality characteristics of Huso huso during frozen storage. Practical-type diets containing 0 or 250 mg vitamin E kg⁻¹ with three lipid sources, fish oil (FO), soybean oil (SO) and canola oil (CO), were fed to H. huso for 120 days. Fillet samples were analysed fresh or after storage at −18 ± 1 °C for 12 months. Replacement of FO by SO and CO in diets for H. huso significantly altered the fatty acid (FA) profile, which also influenced the FA composition during frozen storage. Dietary vitamin E had a significant effect on muscle vitamin E content and lipid oxidation during storage (P > 0.05). Oxidation was reduced for fish fed vitamin E and results showed that dietary vitamin E supplementation can slow down the level of lipid oxidation in H. huso muscles during frozen storage.     

干腌火腿皮下脂肪的特性与食用品质的关系

根据国外干腌火腿的研究结果,分析火腿皮下脂肪组织的组成特点及在加工过程中的变化,发现含有2个或3个不饱和脂肪酸的三酰基甘油酯(POO,OOL和POL),熔点较低,在常温下呈液体状态,适宜于脂肪水解酶在水-油界面的反应,优先发生水解反应,释放出棕榈酸、油酸和亚油酸。在游离脂肪酸构成中,油酸和亚油酸的比例并没有增加,亚油酸的比例却明显降低,说明不饱和脂肪酸被氧化形成了其他物质。在加工期的前6个月,脂肪水解程度最大,使低熔点的三酰基甘油酯比例降低,高熔点的三酰基甘油酯比例相应提高,降低了脂肪组织的油腻感,硬度增加,色泽变成透明的玻璃状,熟制后口感脆嫩、利口。不饱和脂肪酸的适度氧化,最终形成许多挥发性化合物,赋予脂肪组织特有的腌腊风味。