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.     

Changes in lipids of whole and minced rayfish (Raja clavata) muscle during frozen storage

The effects of the storage temperature (?18 °C and ?40 °C) and the addition of butylhydroxytoluene (BHT) on the different classes of lipids (phospholipids, triacylglycerides, free fatty acids, sterols and sterol esters plus waxes) and the fatty acid composition of minced (8 and 12 mm) and whole rayfish wing muscle stored for 1 year in the frozen state were studied. The phospholipid content decreased significantly and the free fatty acid content increased significantly at both storage temperatures, but more pronounced, at ?18 °C. Significant differences were found between phospholipid and free fatty acid contents of the minced and the whole samples, which again were more pronounced at ?18 °C. A significant increase of the major fatty acids (22∶: 6n-3 and 16:0) was observed after 1 year in the frozen state. Significant differences were also obtained between the samples stored at ?18 °C and at ?40 °C; the lower the storage temperature, the higher their content. The polyunsaturated fatty acid (PUFA) content increased significantly in all the samples. Significant differences were found between the samples stored at ?18°C and at ?40°C. The lower the temperature, the higher the PUFA content. Nonsignificant differences were observed between the 8-mm and the 12-mm minced samples. Non-significant differences were found between the samples stored in the presence and in the absence of BHT. Mincing hastened hydrolytic and oxidative processes, which were slowed down at the lower storage temperature. Nonetheless, nonsignificant differences were found between both particle sizes.     

油炸中棕榈油与鸡柳脂肪酸组成的变化及其相互影响

为研究油炸过程中棕榈油及鸡柳脂肪酸组成变化及相互影响规律,利用气相色谱法对棕榈油以及炸鸡柳中脂肪酸组成的变化进行分析,并用国标法测定油炸油的酸价和过氧化值,借助主成分分析法探讨油炸油脂肪酸组成对油脂氧化稳定性的影响。结果表明:油炸温度较低(≤200℃)时,棕榈油脂肪酸没有明显变化,在温度极高(>200℃)时,棕榈油中不饱和脂肪酸含量显著下降(p<0.01),反式脂肪酸的含量显著增加(p<0.01)。鸡柳在油炸过程中吸收油炸油,并且吸收油脂的量随着炸制时间的延长而增加。同时,鸡柳中浓度高的脂肪酸C20∶4、9c C16∶1、9c12c C18∶2、9c12c15c C18∶3也会释放到棕榈油中。主成分分析结果显示棕榈油中多不饱和脂肪酸C18∶2和C18∶3对于酸价和过氧化值的影响最大。      

冻藏过程中文昌鸡肉肌原纤维蛋白变化规律研究

为了探讨冻藏过程中文昌鸡肉肌原纤维蛋白变化规律,以肌原纤维蛋白盐溶性,Ca2+-ATPase活性,巯基含量以及质构分析为指标,研究了肌原纤维蛋白在-18、-30、-78℃下冻藏时的变性情况。结果表明,冻藏温度越低,冻藏时间越短,肌原纤维蛋白质的生化特性越稳定。冻藏前10d,肌原纤维蛋白盐溶性显著降低,-18、-30和-78℃条件下分别降低了41.7%、39.9%和33.3%;Ca2+-ATPase活性随冻藏时间的延长而降低,第40d时,-18、-30、-78℃条件下分别降低了46.15%、44.62%、41.54%;巯基含量在0³0d内逐渐降低,31⁴0d内变化不明显,第30d时,-18、-30、-78℃条件下分别降低了41.27%、37.81%、34.29%;另外,鸡肉的硬度、弹性、内聚性随着冻藏时间的延长都有不同程度的降低,且经Pearson相关系数分析发现,Ca2+-ATPase活性、巯基含量与质构参数之间呈现出较好的相关性。      

The effect of antioxidants on the quality changes of cuttlefish (Sepia pharaonis) muscle during frozen storage

The changes in quality of cuttlefish (Sepia pharaonis) treated with 5% NaCl and 0.3% H₂O₂ and soaked with and without different antioxidants during frozen storage at -18 °C for 16 weeks were investigated. Thiobarbituric acid reactive substances (TBARS) in all cuttlefish samples increased when the storage time increased (P<0.05). Ascorbate (ASC) and erythorbate (ERT) showed a prooxidative effect while EDTA and tripolyphosphate (TPP) had no antioxidative effect in frozen cuttlefish. Soaking the cuttlefish in 5% NaCl and 0.3% H₂O₂ for 15 min could improve the color of cuttlefish by increasing the L^*-value and decreasing the a^*-value. ASC, ERT, EDTA and TPP solutions had no impact on the a^*-value and L^*-value of cuttlefish during frozen storage. However, the treated samples, which were soaked in ASC and ERT solutions had an increased b^*-value during frozen storage. Surface hydrophobicity (S₀ANS) of cuttlefish natural actomyosin increased when the frozen storage period increased up to 12 weeks. The increase in disulfide bond content was generally coincidental with the decrease in sulfhydryl content. ASC, ERT, EDTA and TPP had no significant effect on those changes. Protein solubility decreased slightly during prolonged storage. Soaking cuttlefish with 5% NaCl and 0.3% H₂O₂ together with 0.5% TPP could retard the decreases in solubility and increase in thaw drip of frozen cuttlefish. However, ASC, ERT and EDTA showed no impact on the solubility and thaw drip of frozen cuttlefish.     

Amino acid composition of storage proteins of a promising chickpea (Cicer arietinum L) cultivar

The amino acid compositions of flours made from the cotyledons and from the whole seeds of a disease-resistant, stable and high-yielding cultivar of chickpea (Cicer arietinum L) cv H75–35, known locally as Gaurav, have been analysed. These, together with similar analyses of the albumin, globulin, legumin and vicilin protein fractions, have been compared with those of other legumes. Seed protein content was 19·8 % with globulin constituting 62·4 % of the total seed protein. The ratios of albumin to globulin and legumin to vicilin were 1:4 and 6:1, respectively. The proportion of basic amino acids in the albumin was low whereas the reverse was true in the globulin. The legumin fraction seems to be superior in terms of total essential amino acids to those from other sources. Sulphur amino acids were the most limiting, followed by tryptophan or threonine depending on the fraction. However, the ratio of methionine to cystine was high (2·76:1). The extent of the sulphur amino acid deficiency was assessed, and possible approaches for its improvement are outlined.     

Changes in lipids of whole and minced rayfish (Raja clavata) muscle during frozen storage

The effects of the storage temperature (–18 °C and –40 °C) and the addition of butylhydroxytoluene (BHT) on the different classes of lipids (phospholipids, triacylglycerides, free fatty acids, sterols and sterol esters plus waxes) and the fatty acid composition of minced (8 and 12 mm) and whole rayfish wing muscle stored for 1 year in the frozen state were studied.The phospholipid content decreased significantly and the free fatty acid content increased significantly at both storage temperatures, but more pronounced, at –18 °C. Significant differences were found between phospholipid and free fatty acid contents of the minced and the whole samples, which again were more pronounced at –18 °C. A significant increase of the major fatty acids (22: 6n-3 and 16:0) was observed after 1 year in the frozen state. Significant differences were also obtained between the samples stored at –18 °C and at –40 °C; the lower the storage temperature, the higher their content. The polyunsaturated fatty acid (PUFA) content increased significantly in all the samples. Significant differences were found between the samples stored at –18°C and at –40°C. The lower the temperature, the higher the PUFA content. Nonsignificant differences were observed between the 8-mm and the 12-mm minced samples. Non-significant differences were found between the samples stored in the presence and in the absence of BHT. Mincing hastened hydrolytic and oxidative processes, which were slowed down at the lower storage temperature. Nonetheless, nonsignificant differences were found between both particle sizes.

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Lipoid-Veränderungen in ganzem und zerkleinertem Rochenmuskel (Raja clavata) während der Gefrierlagerung

Zusammenfassung Der Einfluß der Gefriertemperatur (–18 °C und –40 °C) und der Zugabe von Butylhydroxytoluene (BHT) auf die verschiedenen Lipoid-Klassen (Phospholipoide, Triacylglyceride, freie Fettsäuren, Sterole und Sterolester bzw. Sterolwachse und die Zusammensetzung der Fettsäuren in ganzem und zerkleinertem (8 und 12 mm) Rochenmuskel wurden nach einem Jahr Gefrierlagerung untersucht. — Der Phospholipoid-Anteil sank deutlich und der Anteil an freien Fettsäuren nahm deutlich zu bei beiden Gefriertemperaturen, besonders bei –18 °C. Deutliche Unterschiede bei beiden Lipoid-Typen wurden zwischen den zerkleinerten und den ganzen Proben gefunden, wobei sich die größten Unterschiede bei –18 °C zeigten. Ein signifikanter Anstieg der häufigsten Fettsäuren (22:6n-3 und 16:0) wurde nach einem Jahr Gefrierhaltung festgestellt, je niedriger die Gefriertemperatur, desto höher ihr Anteil. Der Anteil an polyungesättigten Fettsäuren nahm bei allen Proben deutlich zu, je niedriger die Temperatur, desto höher ihr Anteil. Unerhebliche Unterschiede wurden zwischen den auf 8 mm und 12 mm zerkleinerten Proben gefunden. In keinem der untersuchten Parameter zeigten sich signifikante Unterschiede bei Vorhandensein oder Nicht-Vorhandensein von BHT. Die Zerkleinerung beschleunigte die hydrolytischen und oxidativen Prozesse, die bei niedrigerer Gefriertemperatur langsamer waren, trotzdem wurden keine signifikanten Unterschiede zwischen den beiden Partikel-Größen festgestellt.

     

Sensory quality of short- and long-term frozen stored pork products. Influence of diets varying in polyunsaturated fatty acid (PUFA) content and iodine value

Predicting aspects of pork quality is becoming increasingly important from a nutritional as well as a technological point of view. Here, the influence of increasing PUFA and iodine values (IV) in feed and pigs on sensory qualities of short- and long-term frozen stored products was investigated. Entire male and female grower-finisher pigs were fed diets with iodine value products of 48 (LowIVP), 77 (MedIVP) or 99 (HighIVP) according to a restricted feeding scale. Ribs, chops and meat balls were short- (0-3 months) and long-term (6-9 months) frozen stored before sensory profiling. C18:2n−6 increased linearly in backfat with increased dietary inclusion. No negative effect on sensory quality was found in short-term stored products. After long-term storage the lean chops was the product most affected. Increasing the dietary IVP led to an increased rancid and total odour and flavour intensity, and to reduced meat and sour odour and flavour.     

大豆油在储存过程中的变化

收集储备大豆原油在储存过程中酸值和过氧化值的数据,分析其在储存过程中的变化规律。结果表明:大豆原油的酸值和过氧化值变化规律相同,酸值随着储存时间的延长呈缓慢线性增长,年变化值在0.2～0.4 mg/g,过氧化值随着储存时间延长呈平稳慢慢上升趋势,其变化值受环境温度影响较大,在外部温度和氧气突然增加时过氧化值迅速上升,当达到一定值后分解下降。     

Chemical compositions and characteristics of farm raised giant catfish (Pangasianodon gigas) muscle

Proximate composition, chemical and physical properties of dorsal, ventral and lateral line cuts of farm raised giant catfish were determined. Protein, fat and ash content of the different cuts averaged 16.88, 4.45 and 1.24 g/100 g, respectively. Dorsal contains higher protein concentrations (19 g/100 g) than other two parts (p < 0.05). Ventral showed the highest hydroxyproline content (0.83 mg/g). Differences in lipid composition and fatty acid profiles were found among different cuts with highest phospholipids in the dorsal and highest triglyceride in both ventral and lateral line (p < 0.05). All the meat cuts contained high saturated fatty acid, followed by mono- and polyunsaturated fatty acid. High muscle hardness and toughness was found in the dorsal than that in the ventral (p > 0.05). The highest content of myoglobin and total pigment in lateral line resulted in the highest redness index (a*/b*) of this part. Three major nitrogenous compositions classified based on solubility in giant catfish muscle were myofibrillar, sarcoplasmic and alkaline soluble proteins.     

不同贮藏温度下猪油品质变化及氧化动力学模型构建

目的：了解贮藏温度对猪油氧化的影响规律。方法：将猪油分别于50,60,70 ℃下贮藏,测定贮藏过程中猪油的过氧化值、硫代巴比妥酸值和酸价等,并建立各个指标与贮藏温度和贮藏时间之间的氧化动力学模型。结果：随着贮藏时间的延长,猪油的氧化程度加深,贮藏温度越高,氧化速率越快;贮藏过程中猪油的过氧化值、硫代巴比妥酸值和酸价变化均符合一级动力学模型,通过阿伦尼乌斯方程求得其活化能分别为15.718 2,21.255 0,2.299 6 kJ/mol,模型验证实际测量值与预测值相关系数较高。结论：不同贮藏温度下,猪油的氧化程度随贮藏时间的延长而不同程度加深,建立的氧化动力学模型可以快速评估和预测猪油的氧化程度,且猪油应尽量低温贮藏。     

An investigation of rancidity inhibition during frozen storage of Wels catfish (Silurus glanis) fillets by previous ascorbic and citric acid treatment

The effect of preliminary ascorbic and citric acid (AA and CA, respectively) soaking treatments on the rancidity development in Wels catfish ( Silurus glanis ) fillets during further frozen storage (−18 °C; up to 6 months) was studied. Rancidity development was measured by biochemical quality indices (formation of free fatty acids, peroxides and secondary oxidation products) and compared with sensory analysis (appearance, rancid odour and consistency) and general chemical analyses (pH, expressible moisture and heme iron contents). When compared with control samples, AA- and CA-treated samples showed a lower ( P  < 0.05) formation of primary and secondary lipid oxidation compounds that was corroborated by a longer ( P  < 0.05) shelf-life time as a result of a lower rancid odour formation. According to these results, control samples showed a higher ( P  < 0.05) heme iron breakdown (months 3–6) and a lower ( P  < 0.05) water-holding capacity (higher expressible moisture value) (month 6).     

油炸过程中3种植物油脂肪酸组分含量及品质的变化

为研究油炸过程中大豆油、山茶油、棕榈油品质的变化,用国标法测定酸价和过氧化值,并利用高极性色谱柱CP-Sil 88对植物油中脂肪酸,特别是反式脂肪酸(TFA)组分和含量的变化进行分析。结果表明:顺式亚油酸(53.06%)、顺式油酸(82.26%)、棕榈酸(49.7%)分别是大豆油、山茶油、棕榈油中主要的脂肪酸。大豆油、棕榈油低温油炸时油脂中总TFA含量不会存在明显变化,平均为15.51mg/g和1.35mg/g。随着油炸时间延长,山茶油中反式油酸含量增加了63.82%。油炸过程中,3种植物油的酸价由高到低依次为山茶油>棕榈油>大豆油,大豆油和棕榈油的过氧化值先增大后减小。在8h连续使用时间内,酸价和过氧化值都未超过煎炸油的卫生标准。综合以上结果,棕榈油中总TFA含量最低,更适合于短时间循环使用的食品加工过程。     

Cryoprotective effects of trehalose and sodium lactate on tilapia (Sarotherodon nilotica) surimi during frozen storage

The cryoprotective effects of trehalose and sodium lactate at level of 8% (w/w) in tilapia surimi were studied in comparison with a conventional cryoprotectant (sucrose/sorbitol, 1:1) during extended storage at −18 °C for up to 24 weeks. All present cryoprotectants retarded the protein changes as evidenced by the lowered decrease in salt extractable protein (SEP), Ca²⁺-ATPase activity, total sulfhydryl content as well as the impeded increase in disulfide bond content and surface hydrophobicity. The gel-forming ability of frozen surimi was more retained with addition of cryoprotectants. Among all cryoprotectants used, trehalose exhibited the greatest protective effect on protein denaturation as shown by the effectiveness in maintaining Ca²⁺-ATPase activity and protein solubility. Additionally, the greatest breaking force and deformation were obtained in surimi added with 8% trehalose throughout the frozen storage up to 24 weeks. Sodium lactate showed a similar cryoprotective effect to sucrose/sorbitol blend. Therefore, trehalose and sodium lactate appeared to be promising alternative cryoprotectants for surimi owing to their low sweetness and caloric value.     

Comparison of gilthead sea bream (Sparus aurata) and hake (Merluccius merluccius) muscle proteins during iced and frozen storage

Gilthead sea bream (Sparus aurata) and hake (Merluccius merluccius) muscle behave differently during storage, whether in ice or deep frozen. Rapid changes have been observed in the texture of hake muscle during frozen storage, while gilthead sea bream has proved to be more stable. In order to ascertain the role of muscle proteins in the changes observed during storage, parameters related to protein functionality and the properties of extracted natural actomyosin (NAM) were studied initially and during storage in ice or at ?20 °C. Initially, the parameters related to functionality had higher values in hake muscle and extracted NAM than in gilthead sea bream. At the end of iced storage (22 days), less myosin heavy chain (MHC) and actin were extracted from hake, but there was practically no change in gilthead sea bream. This decrease was not accompanied by lower Ca²⁺‐ATPase activity. Freezing produced no drastic changes, with lower values for gilthead sea bream. However, this species was more stable after 1 year, except for the Ca²⁺‐ATPase activity of NAM. This suggests that the changes that hake proteins underwent during storage particularly affected properties related to aggregation, whereas in gilthead sea bream the changes hardly affected the formation of soluble or insoluble aggregates but did affect the active sites of myosin. © 2002 Society of Chemical Industry     

Changes in carbohydrates, proteins and lipids of finger millet after hydrothermal processing

Finger millet was soaked, steamed and dried to prepare hydrothermally processed millet, followed by decortication to prepare decorticated millet. The physicochemical properties and carbohydrate, protein and lipid profiles of control and processed millet were determined. The carbohydrates were fractionated to amlypectin and amylose equivalent fractions using gel permeation chromatography. The non-starch polysaccharides were isolated and their alditol acetyl derivatives were characterized by gas chromatography (GC). The proteins were extracted using different solvents and the total proteins were fractionated using SDS-PAGE. The ether extractable lipids were esterified and fractionated through GC. Hydrothermal processing decreased the amylopectin fraction and increased the amylose equivalent portion of the starch. Decortication further lowered the first fraction and increased the second fraction. A decrease in cold, hot water soluble and hemicellulose-B fractions and an increase in pectic polysaccharides, hemicellulose-A and cellulosic fractions were observed as a result of hydrothermal processing. Decortication significantly reduced the total non-starch polysaccharides specifically the cellulose fraction. Hydrothermal processing decreased the overall extractability of proteins by 50% but decortication increased it to 80%. It was observed that hydrothermal treatment did not change the gross nutrients composition of finger millet but for their profile. Decortication of hydrothermally processed millet caused significant changes in the nutrient contents and also in their profiles.     

食用油使用过程中存贮条件对其氧化稳定性的影响研究

研究了大豆油、菜籽油、棕榈油等几种食用油在使用过程中不同存贮条件下的氧化稳定性。将食用油启封,放置在不同的环境里,检测其过氧化值和酸值的变化。结果表明:避光存贮31 d,食用油的过氧化值均低于8 mmol/kg,酸值(KOH)达到0.26~0.35 mg/g;而在室内日光直接照射的条件下存贮31 d,各食用油的过氧化值均高于10 mmol/kg,酸值(KOH)达到0.35~0.45 mg/g。实验表明,启封后的食用油,存贮于避光处可以连续使用30 d以上,而置于室内日光直接照射条件下,其连续使用期只有3周。对比实验中,棕榈油氧化稳定性优于其他油脂。     

不同条件对油茶籽油储藏稳定性的影响

研究了不同加工工艺(压榨毛油、压榨精炼油、浸出精炼油)、不同容器(铁罐、无色玻璃瓶和塑料瓶)及不同光照条件(光照、避光)下油茶籽油的储藏稳定性.结果显示:不同加工工艺油茶籽油样品中浸出精炼油和压榨精炼油储藏稳定性较好,压榨毛油最差;光照是影响油茶籽油储藏稳定性的关键因素,油茶籽油包装及储藏要尽量采用不透光材料或避光储藏;3种容器材料中,铁罐储藏效果最好,玻璃瓶次之,塑料瓶最差.     

Quality changes in frozen whole and gutted anchovies during storage at −18°C

Fresh samples of whole and gutted anchovies were blast frozen at −35°C and stored at −18°C. The quality of the samples was examined as organoleptic, microbiological and chemical changes during the storage period. Gutting had no significant effect on the quality of the final product. Sensory quality was good for up to 90 days of storage. No increase in microbial activity was detected, but some oxidative and hydrolytic deterioration of fats were observed. The final product was still edible after 180 days.     

Glazing herring (Clupea harengus) fillets with herring muscle press juice: effect on lipid oxidation development during frozen storage

In this study, fish muscle press juice, PJ, was evaluated as an antioxidative liquid for glazing of fish fillets prior to frozen storage. PJ has in previous studies efficiently protected fish mince lipids against haemoglobin‐mediated oxidation. Frozen herring fillet were glazed with water, PJ or 50 mm phosphate buffer of the same pH as herring PJ (6.5). Over 52 weeks, peroxide value (PV), TBA‐reactive substances (TBARS), rancid odour and colour were monitored. From 26 to 52 weeks, water‐glazed fillets were significantly (P < 0.05) more oxidised compared to fillets glazed with PJ or buffer, most clearly shown by PV and TBARS data. The protective effects of both PJ and buffer compared to water could indicate a role, for example, of the physiological ionic strength. The finding that PV became elevated in PJ which was frozen stored alone in a thin layer indicates that PJ stripped from, for example, trace lipids and haemoglobin would provide better protection.