Lipid Changes in Sea Urchin Gonads during Storage

In lipids of salted sea urchin gonads, the changes in contents of neutral lipids (NL), glycolipids (GL) and phospholipids (PL), in peroxide and carbonyl values, in lipid class compositions of NL and PL, and in fatty acid composition were investigated as a function of storage time. NL increased while GL and PL decreased by autolysis during 180 days storage. The increase of NL resulted from free fatty acids (FFA) [plus fatty acid ethyl esters (FAEE)] generated enzymatically by hydrolysis of PL and GL. Triglycerides were stable throughout a period of storage. In heat-treated and salted gonads, NL, GL and PL remained nearly unchanged during storage, and FFA and FAEE could not be detected. The oxidation of lipids was not detected during 180 days storage, although salted gonads had high content of polyunsaturated fatty acids.     

人工加速老化对茶叶籽储藏特性的影响

研究了人工加速老化对茶叶籽含水率、含油率、可溶性蛋白、脂肪酶、脂肪氧化酶活性、酸价、过氧化值的影响及脂肪酸组分的变化。结果表明,人工加速老化促进茶叶籽老化进程,老化程度与老化强度成正比。随着人工加速老化时间的延长,茶叶籽含水率上升,可溶性蛋白含量下降;茶叶籽脂肪酶活力下降,脂肪氧化酶活力上升;茶叶籽油酸价和过氧化值增高;茶叶籽含油率逐渐升高,不饱和脂肪酸与饱和脂肪酸比值下降,单不饱和脂肪酸与多不饱和脂肪酸比值上升。通过对茶叶籽老化不同阶段储藏特性的测定可以预测茶叶籽劣变程度。     

低温锡箔烘烤和微波处理对南瓜籽油脂肪酸组成变化及货架期影响的研究

本研究比较低温锡箔烘烤和微波处理两种常用加工方式对南瓜籽油贮藏期间中性脂肪酸、磷脂脂肪酸与总脂肪酸组成的影响,同时,通过测定南瓜籽油酸价（Acid value, AV）与过氧化值（Peroxide value, POV）的变化,结合一级化学反应动力学方程和Arrhenius方程建立南瓜籽油贮藏动力学模型预测其货架期变化。低温锡箔烘烤和微波预处理的南瓜籽油总脂肪酸中PUFA相对含量都丰富,从脂肪酸组成角度来看耐贮性良好,低温锡箔烘烤组较微波组货架期更长。     

Changes in lipid composition,fatty acid profile and lipid oxidative stability during Cantonese sausage processing

Lipid composition, fatty acid profile and lipid oxidative stability were evaluated during Cantonese sausage processing. Free fatty acids increased with concomitant decrease of phospholipids. Total content of free fatty acids at 72 h in muscle and adipose tissue was 7.341 mg/g and 3.067 mg/g, respectively. Total amount of saturated, monounsaturated and polyunsaturated fatty acids (SFA, MUFA, and PUFA) in neutral lipid exhibited a little change during processing, while the proportion of PUFA significantly decreased in the PL fraction. The main triacylglycerols were POO + SLO + OOO, PSO (P = palmitic acid, O = oleic acid, L = linoleic acid, S = stearic acid), and a preferential hydrolysis of palmitic, oleic and linoleic acid was observed. Phosphatidylcholines (PC) and phosphatidylethanolamines (PE) were the main components of phospholipids and PE exhibited the most significant degradation during processing. Thiobarbituric acid values (TBARS) increased while peroxide values and hexanal contents varied during processing.     

Lipolytic and oxidative changes in Iberian dry-cured loin

This study was conducted using 61 Iberian pigs from four different genetic lines fattened under two different rearing systems. Fatty acid composition of neutral lipids (NL), polar lipids (PL) and free fatty acids (FFA) of the 61 fresh loins and their corresponding dry-cured loins and indices of lipid oxidation (hexanal, TBARS and rancid flavour) of the dry-cured loins were analyzed. Although the total amount of fatty acids from PL decreased most (89.77%), the fatty acid profile of FFA from dry-cured loin was more similar to that of NL from fresh loins. Monounsaturated fatty acids (MUFA) were the most abundant FFA type (260mg/100g muscle dry matter) followed by saturated fatty acid (SFA) (256mg/100g muscle dry matter) and polyunsaturated fatty acids (PUFA) (148mg/100g muscle dry matter). Neither genetic line nor rearing system showed any significant (P>0.05) effect on the decrease of fatty acids in the lipid fractions studied. The important decrease in PUFA from NL (43.70%) and PL (89%) was not reflected in higher oxidative indices in dry-cured loin. Neither PCA nor Pearson's correlation showed any clear relationships between lipolytic changes and oxidative indices.     

Lipolysis in dry-cured ham: Influence of salt content and processing conditions

Fatty acid composition of neutral lipids (NLs), polar lipids (PLs) and free fatty acids (FFA) from the intramuscular fat of Semimembranosus and Biceps femoris muscles was analysed in 46 Iberian dry-cured hams processed with different amounts of salt (6% high salt batch – HS vs. 3% low salt batch – LS w/w) and different processing systems (traditional – T vs. modified – M).

Total amounts of saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids in NLs decreased in similar proportions during processing of the hams as well as SFA, MUFA and PUFA in the PL fraction, whereas the amounts of SFA, MUFA and PUFA of FFAs significantly increased in Semimembranosus and Biceps femoris muscles. The amount of total fatty acids (TFA), from NLs and PLs, decreased in both muscles throughout the processing. Such a decline was more intense in HS hams than in LS ones, which could be a sign of a promoting effect of sodium chloride on lipolysis. However, the increase in FFA content throughout processing was not more intense in HS hams. Processing conditions studied in this work did not affect the changes in the fatty acid content of each fraction.     

CONTRIBUTION OF PHOSPHOLIPIDS TO HEADSPACE VOLATILES DURING STORAGE OF PECANS

The relationship between headspace volatiles and lipid class fatty acid composition was investigated in pecans subjected to room temperature storage for 8 months. During early stages of storage, pentanal predominated in the pecan headspace, whereas at later stages hexanal predominated. Quantities of triacylglycerols recovered from pecans did not change significantly during storage, whereas a decrease in phospholipid content and an increase in free fatty acid content were seen. While losses of polyunsaturated fatty acids (PUFA) in triacylglycerols and free fatty acids only occurred during the last month of storage, PUFA losses were recorded in the phospholipid fraction by 5 months. Based on a strong negative correlation (R =?0.98) between hexanal and its precursor fatty acid (18:2) in phospholipids, the results suggested that membrane lipids would be a primary site of attack during the early stages of oxidation. Future studies with oilseeds, such as pecans, should therefore examine the possibility that variations in phospholipid fatty acid composition could explain cultivar differences in storage stability.     

Effect of frozen storage on lipids and lipolytic activities in the longissimus dorsi muscle of the pig

 Samples of longissimus dorsi muscle from pigs were vacuum-packed and stored at –18  °C for a 6-month period. The quantity of total lipids, non-polar lipids, phospholipids and cholesterol remained unchanged during storage. However, there was a decrease (1.4%) in the polyunsaturated fatty acid percentage of the phospholipid fraction after 6 months of frozen storage, mainly due to the decrease in linoleic fatty acid. Nevertheless, there was no change in fatty acid composition of the non-polar lipid fraction. Phosphatidylethanolamine was the phospholipid most affected during the frozen storage, with a significant decrease from an intial percentage of 26.6% to 23.0% after 6 months of storage. Important activities of muscle lipolytic enzymes were still recovered after the storage, which explains the continuous release of free fatty acids reported during the process, with a net increase of 50.6 mg/100 g dry matter. The highest release of free fatty acids was reported during the 1st month of frozen storage. At the 6th month of frozen storage the compositions of both the free fatty acid and phospholipid fractions were similar. With respect to oxidation, the thiobarbituric acid test number showed a slight increase during the process while the peroxide value remained unchanged. Received: 16 March 1998 / Revised version: 17 June 1998     

不同温度处理的风干牛肉贮藏过程中脂肪变化

为了研究干燥温度对风干牛肉贮藏过程中脂肪酸组成的变化规律,选取新疆褐牛后腿肉为研究对象,经腌制后分别进行20 ℃ 48 h、40 ℃ 20 h、50 ℃ 12 h、60 ℃ 8 h的风干处理,冷却后置于4 ℃冰箱贮藏,分别在第0、15、30天和第60天取样,检测其pH值、过氧化值、酸价、硫代巴比妥酸反应底物（thiobarbituric acid reaction substrate,TBARS）值、脂肪含量和脂肪酸组成变化。结果表明：随着贮藏时间的延长,pH值先降低后略微升高（P＞0.05）;处理温度对脂肪含量影响显著（P＜0.05）,而贮藏时间对脂肪含量影响不显著（P＞0.05）;相同温度处理的样品过氧化值、酸价和TBARS值随着贮藏时间的延长呈增加的趋势;处理温度对风干牛肉中肌内脂肪酸组成、甘油三酯和磷脂相对含量影响也不明显,但对游离脂肪酸含量影响较明显,且温度越高,游离脂肪酸相对含量越高;与20 ℃处理组相比,60 ℃处理组样品中游离脂肪酸相对含量在0、15、30、60 d分别增加了0.84%、1.82%、1.45%、1.14%;50、60 ℃处理组的样品随着贮藏时间的延长,磷脂脂肪酸中多不饱和脂肪酸（polyunsaturated fatty acid,PUFA）相对含量降低,游离脂肪酸中的PUFA相对含量增加。本实验结果可为阐明不同温度影响风干牛肉加工过程中风味形成的原因提供一定参考。     

Effect of vacuum-packaged frozen storage, after cooking, on the phospholipids of Hereford and Bison

Changes in the neutral lipid (NL), phospholipid (PL) and their fatty acid (FA) profiles in lean samples of cooked and cooked, vacuum-packaged, frozen (28 days) Hereford and Bison L. dorsi muscle were analyzed. Samples from Herefords contained more saturated fatty acids (SFA) in the neutral lipid fraction than Bison. Storage decreased the C_18:2, C_18:3, C_20:1 and C_20:4 content of the NL. Bison samples contained more total PL and phosphatidylethanolamine (PE) than Hereford. Storage decreased the content of the least polar of the PL which were eluted in the solvent front (fraction 1), phosphatidylinositol (PI), phosphatidylserine (PS), PE and sphingomyelin (SPH). In the combined PL fraction, there were no differences in the FA profile of Bison and Hereford. Storage resulted in a decrease in the content of C_18:2, C_20:4, unsaturated fatty acid (UFA) and polyunsaturated fatty acid (PUFA) in the combined PL fraction. In the PE fraction, Bison samples contained more C_20:4 and PUFA than Hereford. Storage had no effect on the FA profile of PE. The LPC fraction of Bison samples contained more saturated SFA, UFA and PUFA than Hereford, and with storage these FA decreased. Cooked frozen storage also decreased SFA, UFA and PUFA in PC/LPE.     

Effect of frozen storage on lipids and lipolytic activities in the longissimus dorsi muscle of the pig

 Samples of longissimus dorsi muscle from pigs were vacuum-packed and stored at –18  °C for a 6-month period. The quantity of total lipids, non-polar lipids, phospholipids and cholesterol remained unchanged during storage. However, there was a decrease (1.4%) in the polyunsaturated fatty acid percentage of the phospholipid fraction after 6 months of frozen storage, mainly due to the decrease in linoleic fatty acid. Nevertheless, there was no change in fatty acid composition of the non-polar lipid fraction. Phosphatidylethanolamine was the phospholipid most affected during the frozen storage, with a significant decrease from an intial percentage of 26.6% to 23.0% after 6 months of storage. Important activities of muscle lipolytic enzymes were still recovered after the storage, which explains the continuous release of free fatty acids reported during the process, with a net increase of 50.6 mg/100 g dry matter. The highest release of free fatty acids was reported during the 1st month of frozen storage. At the 6th month of frozen storage the compositions of both the free fatty acid and phospholipid fractions were similar. With respect to oxidation, the thiobarbituric acid test number showed a slight increase during the process while the peroxide value remained unchanged.     

Chemical Deterioration of Frozen Bovine Muscle at −4° C

SUMMARY— During an 8-week storage period of bovine muscle at −4°C, the total extractable protein content dropped from 91 to 51%. This decline, accompanied by a decrease in water-binding capacity of muscle, was primarily caused by the insolubilization of both sarcoplasmic proteins and actomyosin. The increase in the free fatty acid content from about 1.6 to 9.1% over the 8-week period may be attributed to phospholipid hydrolysis. The TBA number rose progressively throughout the entire storage period while the peroxide value increased to a maximum in 2 weeks of storage and then decreased to a constant value of 7.     

Lipid damage during frozen storage of Atlantic halibut (Hippoglossus hippoglossus) in active packaging film containing antioxidants

The use of peroxide value (PV), free fatty acids (FFA), thiobarbituric acid reactive substances (TBARS) and p-anisidine value (PA) proved suitable for studying lipid hydrolysis and primary and secondary lipid oxidation in samples of Atlantic halibut throughout frozen storage. After twelve months, the FFA values in the samples packaged with the film containing natural antioxidants (extracted from barley husks) were similar to the FFA value in the control sample after 9 months. Maximum peroxide value in the samples packaged with the antioxidant-containing film was found one month after the maximum value observed in the control sample. After six months, the concentration of malondialdehyde in the control sample was approximately 30–50% higher than in samples packaged in film containing antioxidants. The results confirm the efficacy of natural antioxidants derived from barley husks and antioxidant active packaging film in slowing down lipid hydrolysis and increasing the oxidative stability of Atlantic halibut flesh.     

Quality deterioration in frozen Nile perch (Lates niloticus) stored at −13 and −27°C

Nile perch fillets stored at −13 and −27°C were monitored to determine changes in protein functionality [expressible moisture (EM), water uptake ability (WUA), soluble protein (SP) and emulsion capacity (EC)], changes in lipids [free fatty acids (FFA) and malonaldehyde accumulation] and changes in sensory properties. For samples stored at both temperatures, WUA, EC and SP decreased with time of storage while EM, FFA, malonaldehyde and off-flavors increased. Texture, taste and overall acceptability changed only for the samples stored at −13°.     

Repeated hydrolysis process is effective for enrichment of omega 3 polyunsaturated fatty acids in salmon oil by Candida rugosa lipase

Enrichment of omega 3 polyunsaturated fatty acids (PUFA) in the glyceride fraction of salmon oil was performed by Candida rugosa lipase (CRL)-catalysed hydrolysis. Total omega 3 PUFA content in the product was 38.71% (mol.%), more than double of the initial level. The hydrolysis reaction was scaled up to 1 l in a stirred tank reactor without any decrease in the selectivity of the reaction. Moreover, non-steroselectivity and acyl chain specificity of CRL-catalysed hydrolysis, as well as CRL’s recognition of the whole triacylglycerol molecule, were proved. The product was purified by short path distillation, which was also shown to contribute to the recovery of omega 3 PUFA in residue. After the removal of free fatty acids, the final product was subjected to a second round of hydrolysis to concentrate omega 3 PUFA further to 50.58%. Recoveries of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) decreased slightly after the second round of hydrolysis, while oleic acid (OA) content was not affected.     

Changes in lipids,proteins and kamaboko forming ability of silver carp (Hypophthalmichthys molitrix) mince during frozen storage

Frozen storage of mechanically deboned silver carp (Hypophthalmichthys molitrix) mince for 180 days resulted in a significant (P⩽0.05) decrease in myofibrillar proteins. In contrast, peroxide value (PV), free fatty acids (FFA) and total volatile base nitrogen (TVBN) contents increased significantly (P⩽ 0.05) throughout the storage period. The kamaboko forming ability and the sensory scores of the silver carp mince decreased significantly (P⩽0.05) during the storage period. Texture of the mince was significantly (P ⩽ 0.001) correlated with the decrease in the myofibrillar proteins (salt-soluble proteins), jelly strength and folding test grades; and increase in expressible water percentage, PV, FFA and TVBN content. Based on ‘texture’ of the mince, the product was acceptable for 180 days at −18°C.     

ANCM bibliography

Changes in fatty acid profiles of pork loin chops fried in different culinary fats (olive oil, sunflower oil, butter and pig lard) during 10 days of refrigerated storage were studied. Olive oil-fried loin chops (OOLC) were significantly highest in monounsaturated fatty acids (MUFA) and C18:1. Sunflower oil-fried loin chops (SOLC) showed the highest polyunsaturated fatty acid (PUFA) proportions, mainly due to C18:2 contents. Butter-fried loin chops (BTLC) were significantly richer in saturated fatty acids (SFA), such as C12:0, C14:0 and C16:0, while pig lard-fried loin chops (PLLC) contained moderate proportions of SFA, MUFA and PUFA. Fatty acid profiles of neutral lipids (NL), free fatty acids (FFA) and polar lipids (PL) were slightly changed after refrigerated storage. After 10 days of refrigerated storage, differences among samples fried in different culinary fats were maintained or increased. NL from OOLC had the significantly largest percentages of C18:1 and MUFA, while SOLC had the significantly largest percentages of C18:2 and PUFA. The highest percentages of C12:0, C14:0, C16:0 and SFA were characteristic for pork loin chops fried in butter at the end of the storage period. Refrigerated pork loin chops fried in pig lard showed intermediate percentages of SFA, MUFA and PUFA. OOLC had a more desirable nutritional value than other fried pork loin chops after and before the refrigerated storage.     

Influence of storage time and temperature on lipid deterioration during cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) frozen storage

Lean fish deterioration during frozen storage (−30 and −10 °C) for up to 1 year was studied by the assessment of lipid changes. Comparison between a formaldehyde (FA)-forming species (cod) and a non-FA-forming one (haddock) was carried out. Lipid damages were measured on the basis of free fatty acids (FFA), peroxide value (PV), thiobarbituric acid index (TBA-i) and fluorescent compounds. In both species at −30 °C, most lipid damage indices showed significant correlations with the storage time. However, at −10 °C, only the FFA and fluorescence detections provided significant correlations with the storage time. Comparison between the fish species showed higher lipid oxidation (PV and TBA-i) and hydrolysis (FFA content) in haddock than in cod at −10 °C; however, a higher fluorescence development was observed in cod at the same temperature. At −30 °C, little differences in lipid damage indices were detected between the two species. © 1999 Society of Chemical Industry     

Characteristics of Mackerel Mince Lipid Hydrolysis

The lipid hydrolysis products in minced mackerel stored under vacuum at 2–3°C for 15 days were free fatty acids (FFA) and 1,2-diglycerides (DG); no 1,3-DG br monoglycerides were obsrved, Lysophosphati-dylcholine fLPC and lvsoohosohatidvlethanolamine (LPE) increased and then ddcreased with time: Lysiphosphatidylserie was not observed. More FFA, 1,2-DG, LPC, and LPE were detected in dark muscle than in light muscle. The initial fatty acid composition, by GC, showed no significant differences (α-0.05) among whole, light and dark muscles. When the lipid extracts were separated into three fractions (1: mostly triglycerides; 2: mostly FFA, DG, and cholesterol; and 3: mostly phospholipid), the degree of unsaturation of the lipids in fraction 2 was between those in fraction 1 and 3 and increased with time. These findings support the possibility that fish lipid hydrolysis may affect fish wholesomeness.     

Effect of antioxidant on the fatty acid composition and lipid oxidation of intramuscular lipid in pressurized pork

To investigate the effect of antioxidants on lipid oxidation and fatty acid composition in pressurized pork, minced pork with or without 1% Na(2)EDTA was pressurized at 500MPa before 7days storage at 4°C. TBARS value, lipid content and fatty acid composition in untreated and high-pressure (HP) treated samples were analyzed. HP treatment induced marked increases in TBARS values and lipolysis of partial phospholipids causing an increase of free fatty acid content. Preferential hydrolysis for polyunsaturated fatty acids (PUFA) in phospholipids resulted in the percentage of PUFA in phospholipids decreasing markedly and thereby that in free fatty acids increasing significantly. Addition of 1% Na(2)EDTA to minced pork before HP significantly decreased the TBARS values in pressurized samples, but did not inhibit the lipolysis of phospholipids, causing the fatty acid composition of phospholipids and free fatty acids to change similarly to those samples without Na(2)EDTA.