Effect of brine freezing on the rancidity development during the frozen storage of small pelagic fish species

Brine freezing was applied to two small pelagic underutilised fish species (mackerel, Scomber scombrus; horse mackerel Trachurus trachurus). Rancidity development was studied during their frozen (–18 °C) storage up to 9 months, and quality change results were compared to common freezing conditions (control treatment). Fish samples treated under brine freezing conditions showed a higher lipid oxidation development (peroxide value and thiobarbituric acid index) and worse marks on some sensory attributes (general aspect, odour and colour) than control fish. However, samples treated under brine freezing conditions provided a lower lipid hydrolysis development (free fatty acid formation) and better scores for consistency. Comparison between both fish species led to a higher secondary lipid oxidation formation (thiobarbituric acid index) for mackerel, while horse mackerel showed to be more prone to interaction compound formation (fluorescence detection); however, both fish species showed the same shelf-life times (3 and 5 months for brine and control freezing conditions, respectively). As a result of the brine freezing conditions, an increase in NaCl content in white muscle of both species was observed. According to the results obtained in the present work, the brine freezing treatment is not recommended for these two small pelagic fish species.     

Effect of tocopherol concentration on rancidity development during frozen storage of a cured and an uncured processed pork product

This research evaluated the effect of addition during processing of various concentrations of tocopherol (0-1000 mg/kg) on the subsequent lipid oxidation and rancidity development during frozen storage of two pork products-a coarsely ground cured sausage and an uncured restructured pork roast. The results indicated that tocopherol had little effect on lipid oxidation, as measured by TBARS values and sensory evaluation during frozen storage at -18?°C for 37 weeks for either product. However, lipid oxidation only occurred to a limited extent even in products without tocopherol and was insufficient to cause rancid flavour development. It was, therefore, not possible to determine if tocopherol added during processing was effective as an antioxidant in preventing lipid oxidation in processed pork products during frozen storage.     

Changes in phospholipids of buffalo meat during processing and storage

Effect of broiling and pressure cooking as well as alterations during refrigerated (4°C) and frozen (-10°C) storage on the phospholipids of adult male buffalo muscles viz. Triceps brachii (TB), Longissimus dorsi (LD) and Biceps femoris (BF), i.e. from three different locations were studied. Muscles differed significatly in their total lipid and phospholipid content. Cooking methods significantly altered the total phospholipid content and its fractions. Storage period did not show any significant effect on total phospholipids during refrigerated and frozen storage, whereas certain phospholipid classes viz. lysophosphatidyl choline and lysophosphatidyl ethanolamine + sphingomyelin increased significantly and major phospholipid classes viz. phosphatidyl choline and phosphatidyl ethanolamine decreased significantly. The changes in phospholipid classes were similar both in refrigerated and frozen samples but relatively more pronounced in the former. Palmitic, stearic, oleic and linoleic acids were the four predominant fatty acids in the phospholipids of buffalo meat. The effects associated with the location of muscles were evident. Differences in fatty acid composition of individual muscles in response to heat processing were observed. Heat processing significantly increased the total saturates in TB and LD muscles while it decreased in BF. The total monounsaturated and total polyunsaturated fatty acids of phospholipids decreased during refrigerated and frozen storage indicated by a significant decreass in oleic, linoleic and arachidonic acids.     

Effect of previous chilled storage on rancidity development in frozen horse mackerel (Trachurus trachurus)

Rancidity development during frozen storage (?20 °C) of an underutilised medium‐fat‐content fish species, horse mackerel (Trachurus trachurus), was studied. Special attention was given to the effect of previous chilled storage (0, 1, 3 and 5 days) on the quality of the frozen fish. For this, chemical (free fatty acid and conjugated diene contents; peroxide value, PV; thiobarbituric acid index, TBA‐i; fluorescent compound formation) and sensory (rancid odour and taste) analyses were carried out. Hydrolytic rancidity showed an increase with frozen storage time; however, no effect of previous chilling time was observed on the frozen product. Oxidative rancidity measured by chemical (PV, TBA‐i and fluorescence) and sensory (odour and taste) indices increased with frozen storage time and also with previous chilling time. Satisfactory quality was maintained up to 7 months of frozen storage of horse mackerel provided that a short chilling time (not longer than 3 days) was employed. © 2002 Society of Chemical Industry     

Antioxidant activity of Carob fruit extracts in cooked pork meat systems during chilled and frozen storage

The purpose of this study was to evaluate the effect of adding condensed tannins in the form of non-purified (Liposterine^®) or purified (Exxenterol^®) extracts obtained from Carob fruit to prevent lipid cooked pork meat systems from oxidising during chilling and frozen storage. The antioxidant activity of these extracts was compared with that of α-tocopherol. Meat lipid alteration was evaluated as thiobarbituric acid reactive substances content (TBARS) and polar material-related triglyceride compounds followed by high-performance size-exclusion chromatography (HPSEC). TBARS levels were lower (P < 0.05) in samples containing Liposterine (LM), Exxenterol (EM), and α-tocopherol (TM) than in control sample (CM) under chilled storage. TBARS formation was similar (P > 0.05) for LM and EM but lower (P < 0.05) than for TM. Polar material increased several times in all samples, but significantly less in TM and EM than in LM. Thermal oxidation compounds determined by HPSEC were lower (P < 0.05) in EM than in LM or TM. The changes in polar material were proportionally smaller after six months frozen storage than after chilled storage, with Exxenterol displaying the highest antioxidant protection. Therefore Carob fruit extracts can be successfully used to reduce fat alteration in cooked pork meat at chilled and frozen temperatures.     

Effect of previous gutting on rancidity development in horse mackerel (Trachurus trachurus) during frozen storage at −20 °C

Gutting was applied to fresh horse mackerel (Trachurus trachurus) to study its effect on rancidity development during a prolonged frozen storage (up to 12 months at −20°C). To do so, chemical (free fatty acids, FFA; peroxide value, PV; thiobarbituric acid index, TBA-i; fluorescence ratio, FR) and sensory (odour and taste) analyses were carried out. The results showed that the gutting of horse mackerel led to a higher degree of oxidation in the frozen product, according to the chemical (PV, TBA-i and FR) and sensory (odour and taste) analyses. However, a lower extent of lipid hydrolysis (FFA formation) was detected at the end of the storage (twelfth month) as a result of gutting. It is concluded that the gutting of a medium-fat fish species such as horse mackerel is not recommended as previous treatment to frozen storage.     

速冻中式肉类预制菜肴冻藏过程中品质提升策略研究进展

速冻中式肉类预制菜肴是将速冻调理技术运用到传统中式肉类菜肴的生产中,由于其便捷性(主要是简化了厨房烹饪环节,降低烹饪成本,提高烹饪效率)越来越受到消费者的青睐。然而,速冻中式肉类菜肴在冷冻贮藏期间会发生品质劣变(例如脂肪氧化、风味丢失、风味失真等),不仅影响产品的品质,还会降低消费体验和复购率。因此,本文系统综述了速冻中式肉类预制菜肴在冻藏期间品质变化及品质提升技术,以期为其品质提升策略提供相关技术支持。     

小麦胚芽贮藏期内脂质水解酸败机理解析

以小麦胚芽为研究对象,构建脂质水解酸败的模拟体系以及原位体系,解析小麦胚芽贮藏期内脂质水解酸败的机理。结果表明:光照、氧气和脂肪氧合酶未对小麦胚芽模拟体系中的游离脂肪酸含量产生明显影响,而脂肪酶则显著提升游离脂肪酸生成量;此外,游离脂肪酸生成量随水分活度增加而增加,于水分活度为0.75时达峰值,且小麦胚芽内部结合水和不易流动水含量也呈显著增加趋势,水分以及脂质流动性增加;小麦胚芽原位体系中游离脂肪酸含量随贮藏时间延长而逐渐增加,磷脂酰胆碱含量恰相反,且小麦胚芽脂质体膜遭到破坏,游离出的甘油三酯聚集形成油滴。由此可见,小麦胚芽脂质水解酸败模式主要表现为其脂质体膜中的磷脂酰胆碱降解而释放甘油三酯,而后甘油三酯经由脂肪酶催化水解生成大量的游离脂肪酸,从而产生水解酸败现象。     

Influence of lipids on dimethylamine formation in model systems of hake (Merluccius merluccius) kidney during frozen storage

The role of non-oxidized and oxidized lipids in fish muscle proteins during frozen storage is a matter of controversy: some studies have shown that they have a detrimental effect, whereas others have shown a protective effect through a reduction in the amount of formaldehyde (FA) and dimethylamine (DMA) formed from trimethylamine N-oxide (TMAO) during frozen storage. A model system based on an extract of hake kidney as a source of trimethylamine N-oxide demethylase (TMAO-ase) and the substrate TMAO was prepared to study the effects of non-oxidized lipids and oxidized lipids with increasing peroxide values (POV) and of a cryoprotectant (glycerol) on TMAO-ase activity during frozen storage, using response surface methodology (RSM). At low POV, the oxidized lipids increased DMA formation, but at oxidation levels equal to or higher than 500 meq kg^–1 they reduced the amount of DMA produced. This behaviour corroborates the hypothesis that oxidizing/reducing conditions strongly influence the capacity of the enzyme to catalyse the reaction. However, non-oxidized lipids were found to have a very weak inhibitory effect. Glycerol had a significant inhibitory effect on DMA formation, greater than that of oxidized lipids in the present enzymatic system. Received: 9 July 1996 / Revised version: 20 November 1996     

Changes in the fatty acid composition of dietetic ready-to-cook chicken meat products during frozen storage

A study was made on the fatty acid composition of dietetic ready-to-cook products of boneless chicken legs or breasts prepared by curing using several curing mixtures during frozen storage. Leg muscles were found to be richer in unsaturated fatty acids than breast muscles, substantial differences having been found in the contents of palmitoleic and linolenic acids. During frozen storage, the contents of unsaturated fatty acids were reduced, especially intensively in the leg muscle ready-to-cook products. The fastest changes occurred in linolenic and linolic acids and partly in palmitic acid. The level of oleic acid remained substantially unchanged throughout the storage period. Irrespective of the changes found, the ratio of unsaturated and saturated fatty acids in all the groups studied remained greater than 1 for both types of meat. The application of citrate in the curing mixture had a favourable effect on the changes, in that a minimum alteration in the contents of unsaturated fatty acids was achieved.     

鱼糜冻藏过程中的品质变化动力学研究

以白鲢(Hypophthalmichthys mollitrix)鱼糜为对象,研究其在不同冻藏温度下凝胶特性、Ca2+-ATPase活性、溶解性随冻藏时间和温度的变化规律,建立品质变化动力学模型,以预测和控制冷冻鱼糜的冻藏品质。结果表明,在冻藏过程中,鱼糜的凝胶特性、Ca2+-ATPase活性、溶解性都随冻藏时间的延长而下降。降低冻藏温度,可显著降低鱼糜凝胶性能、Ca2+-ATPase活性和溶解性下降的速率常数,且添加抗冻剂的效果更加明显。低的冻藏温度有利于保持鱼糜品质。     

Wine industry residues extracts as natural antioxidants in raw and cooked chicken meat during frozen storage

The effect of Isabel (IGE) and Niagara (NGE) grape seed and peel extracts on lipid oxidation, instrumental colour, pH and sensory properties of raw and cooked processed chicken meat stored at -18°C for nine months was evaluated. The pH of raw and cooked samples was not affected by the addition of grape extracts. IGE and NGE were effective in inhibiting the lipid oxidation of raw and cooked chicken meat, with results comparable to synthetic antioxidants. The extracts caused alterations in colour, as evidenced by the instrumental (darkening and lower intensity of red and yellow colour) and sensory results of cooked samples. In the sensory evaluation of odour and flavour, IGE produced satisfactory results, which did not differ from synthetic antioxidants. These findings suggest that the IGE and NGE are effective in retarding lipid oxidation of raw and cooked chicken meat during frozen storage.     

Physicochemical properties and sensory analysis of duck meatballs containing duck meat surimi-like material during frozen storage

The physicochemical properties and sensory analysis of duck meatballs containing duck meat surimi-like material during frozen storage were evaluated. Properties of meatballs containing duck surimi-like material prepared by acid solubilization (ACDS), alkaline solubilization (ALDS), and conventional processing (CDS) as well as duck mince (as the control, CON) were compared. ACDS had significantly higher (P < 0.05) moisture and protein content and lower fat content compared with CON. The thiobarbituric acid-reactive substances (TBARS) value of all samples increased as the storage time increased up to week 8 (P < 0.05), but thereafter it decreased in most of the samples. ACDS and ALDS had significantly higher TBARS values (P < 0.05), and these values remained higher than those of the other samples throughout the frozen storage period. Addition of surimi-like material to the meatballs had significant effects (P < 0.05) on springiness, gumminess, and chewiness values of all samples. Ingredients and frozen storage affected most sensory attributes in samples significantly (P<0.05). No significant increase in growth of organisms occurred during 12-wk frozen storage The results indicate that acid-alkaline solubilization methods improve both physicochemical and sensory properties of duck meatballs containing duck surimi-like material. Thus, these techniques should be applicable to product development of duck surimi-like material. PRACTICAL APPLICATION: Surimi-like material from duck meat is an alternative source of meat protein to produce ready-to eat or value-added products. Little is known about duck surimi-like material and physicochemical and sensory properties of such products. Therefore, the results of this study are critical for assessing the possibility of duck meat surimi-like material for human food.     

Role of formaldehyde in formation of natural actomyosin aggregates in hake during frozen storage

During frozen storage of certain lean species of fish, formaldehyde (FA) is formed, giving rise to changes in texture related to the formation of aggregates of myofibrillar proteins. In order to study these aggregates a model system was prepared with natural actomyosin (NAM) (5 mg/ml) and increasing concentrations of formaldehyde. The system was stored frozen at-20° C for 2 months during which solubility in 0.6 M NaCl, Ca²⁺ATPase activity,cis-parinaric acid (CPA) hydrophobicity, SH groups and sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis (PAGE) were measured. — FA caused an immediate loss of Ca²⁺ATPase activity and a decline in soluble protein and CPA hydrophobicity, an effect that was enhanced when the samples were frozen. The electrophoretic profiles of the proteins that remained soluble showed that in both fresh and frozen samples, when FA reacts with NAM the first protein to be insolubilised is myosin, followed by actin, then the troponins and myosin light chains and lastly tropomyosin, depending on the amount of FA and the reaction time. Aggregates of high molecular mass were found at early stages, probably as a result of covalent binding of myosin molecules. When the amount of FA or the frozen storage time was increased, these aggregates became insoluble, forming high-molecular-mass structures and hence were not found in the soluble fraction.

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Die Bedeutung von Formaldehyd bei der Bildung natürlicher Actomyosin-Aggregate im Seehecht während der Lagerung in gefrorenem Zustand

Zusammenfassung Während der Lagerung gewisser Magerfische in gefrorenem Zustand bildet sich Formaldehyd (FA), was die Bildung von Aggregaten myofibrilärer Proteine verursacht. Diese Aggregate wurden im Modell mit Actomyosin (NAM) (5 mg/mL) und wachsenden Formaldehydkonzentrationen untersucht. Die Muster wurden zwei Monate in gefrorenem Zustand bei -20 °C gelagert. Während dieses Zeitraums wurden die Löslichkeit in 0,6 M NaCl, die Ca²⁺ATPase-Aktivität, die cis-Parinarsäure-(CPA)-Hydrophobie und SH-Gruppen gemessen sowie SDS-Polyacrylamid-Gel Elektrophoresen (PAGE) durchgeführt. — FA verursachte einen sofortigen Verlust von Ca²⁺ATPase-Aktivität sowie einen Rückgang löslicher Proteine und in der CPA-Hydrophobie. Dieser Effekt verstärkte sich bei eingefrorenen Mustern. Die elektrophoretischen Profile derjenigen Proteine, die löslich blieben, zeigten sowohl in frischen als auch in gefrorenen Mustern, daß das erste Protein, das bei einer Reaktion von FA mit NAM gelöst wird, Myosin ist, darauf folgen Actin, die Troponine und leichten Myosinketten und schließlich Tropomyosin, was wiederum von der FA-Menge und Reaktionszeit abhängt. In den Anfangsstadien wurden hochmolekulare Aggregate gefunden, die wahrscheinlich das Ergebnis gleichwertiger Bindung von Myosinmolekülen sind. Bei Erhöhung der FA-Menge oder Verlängerung der Lagerzeit bildeten sich hochmolekulare Strukturen, die im löslichen Teil nicht gefunden werden konnten.

     

The development of rancidity in husked and naked oats after storage under various conditions

The levels of hydrolytic and oxidative rancidity have been estimated in husked and naked (huskless) oat varieties stored under different conditions, viz. (i) varying moisture content, (ii) varying oxygen availability, (iii) after bruising, and (iv) after drying at different temperatures. Hydrolytic rancidity increased at higher moisture contents and with storage period but generally the level in naked oats only exceeded that of husked oats if the grain was severely bruised. No oxidative rancidity was detected in husked or naked oats under any of the treatments used.     

不同冻藏温度对鸡胸肉电阻抗特性的影响

为研究不同冻藏温度条件下鸡胸肉的阻抗特性差异,将白羽鸡鸡胸肉在-10、-20与-30℃的条件下分别冻藏3、6、9、12个月,相应的冻藏时间取20块鸡胸肉解冻,在0.05²00 k Hz的频率范围内,选取6个频率点进行电阻抗特性的分析,检测鸡胸肉的阻抗幅值与阻抗相对变化值（Q值）以及理化品质指标。结果表明:相同冻藏时间内,冻藏温度越高,鸡肉的解冻汁液流失率、脂肪氧化程度、剪切力越大（p<0.05）,蛋白质溶解度越小（p<0.05）。随着检测频率的上升,不同冻藏温度鸡胸肉的阻抗幅值均呈下降趋势。在50 Hz频率时,各个冻藏时间的鸡胸肉在不同冻藏温度条件下的阻抗幅值均存在差异（p<0.05）;在200 k Hz频率时,-10℃处理组的阻抗幅值在冻藏3个月与6个月时显著低于其它处理组（p<0.05）。在冻藏过程中,-10℃冻藏组的Q值均显著高于-30℃处理组的Q值（p<0.05）。冻藏温度对解冻鸡胸肉的阻抗幅值与Q值产生影响,阻抗特性的差异能够反映冷冻鸡胸肉品质的差异,不同冻藏温度鸡肉的电阻抗特性差异为阻抗技术在冻肉品质检测中的应用提供了基础。      

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).