Preserving sensory attributes of roasted peanuts using edible coatings

Peanut products are susceptible to develop rancid and off‐flavours through lipid oxidation. Preservation of these products is one of the problems in the peanut industry. The purpose of this work was to determine the sensory and chemical stability of roasted peanuts (RP) coated with different edible coatings: carboxymethyl cellulose (RP‐CMC), methyl cellulose (RP‐MC) or whey protein (RP‐WPI) during storage. Sensory attributes and chemical indicators (peroxide and p‐anisidine values, and conjugated dienes) of lipid oxidation were measured during storage. Chemical indicator values and intensity ratings of oxidised and cardboard flavours had lower increase in RP‐CMC, RP‐MC and RP‐WPI during storage than in RP, whereas roasted peanutty flavour showed a lower decrease. The stability of RP‐CMC is about a double longer with respect to RP. These results indicate that edible coatings preserve the sensory properties of roasted peanuts. Carboxymethyl cellulose exhibited the best protecting effect on this product.     

Chemical Properties of Virgin Coconut Oil

A study on the commercial virgin coconut oil (VCO) available in the Malaysian and Indonesian market was conducted. The paper reported the chemical characteristics and fatty acid composition of VCO. There was no significant difference in lauric acid content (46.64–48.03%) among VCO samples. The major triacylglycerols obtained for the oils were LaLaLa, LaLaM, CLaLa, LaMM and CCLa (La, lauric; C, capric; M, myristic). Iodine value ranged from 4.47 to 8.55, indicative of only few unsaturated bond presence. Saponification value ranged from 250.07 to 260.67 mg KOH/g oil. The low peroxide value (0.21–0.57 mequiv oxygen/kg) signified its high oxidative stability, while anisidine value ranged from 0.16 to 0.19. Free fatty acid content of 0.15–0.25 was fairly low, showing that VCO samples were of good quality. All chemical compositions were within the limit of Codex standard for edible coconut oil. Total phenolic contents of VCO samples (7.78–29.18 mg GAE/100 g oil) were significantly higher than refined, bleached and deodorized (RBD) coconut oil (6.14 mg GAE/100 g oil). These results suggest that VCO is as good as RBD coconut oil in chemical properties with the added benefit of being higher in phenolic content.     

Collaborative study of the oil stability index analysis

The Oil Stability Index Analysis method was subjected to a fifteen-laboratory collaborative study in which the participants used currently available commercial and home-built instruments to provide data to support the approval process as an Official Method of the American Oil Chemists’ Society. The overall average coefficient of variation was 11.3% for samples from 7 to 80 h of stability testing at 110°C.     

Effect of rancidity of Lupinus albus protein-concentrate-based diets on food intake and growth of Wistar rats

The organoleptic properties of a diet are influenced by technological processes and have to be taken into account in food intake studies. The authors studied the food intake suppression associated with rancidity occurring during the storage of diets based on casein or heated or lyophilised lupin protein concentrates, and with or without ascorbic acid supplementation in five groups of 10 weanling Wistar rats for 21 or 26 days. After 15 days of storage, the unsaturated fatty acids were oxidised in heated lupin-protein-based diet without ascorbic acid. Compared to casein, food intake was decreased slightly during the first 10, 16 or 20 days for, respectively, heated lupin protein diet without ascorbic acid, heated lupin protein diet with ascorbic acid, and lyophilised lupin protein diet with or without ascorbic acid. After these periods, food intake decreased strongly. Body weight gain variations did not exactly follow food intake variations. The storage at 20°C could induce first an accumulation of free radicals, which were not detectable in measurement of fatty acids but perceived by rats, and then a fast oxidation of unsaturated fatty acids that increased rancid smell, modified nutritional quality and caused a dramatic decrease of rat food intake. Supplementing ascorbic acid into the diet could diminish the formation of free radicals at the beginning of storage, and consequently could delay food intake decrease. © 1997 SCI.     

天然提取物在传统肉制品加工中的应用研究进展

传统肉制品凭借浓厚的文化底蕴、独特的风味及加工工艺,深受消费者欢迎,但其在加工贮藏过程中易出现氧化酸败、腐败变质、亚硝胺超标等安全问题。这在一定程度制约了传统肉制品加工产业的发展。如何在保持传统风味与特色的同时,能有效降低传统肉制品的安全隐患,达到迎合市场营养健康饮食理念的目的,已然成为传统肉制品加工研究的热门话题。近年来,天然提取物因具有安全、防腐、抗氧化等特性而广泛应用于传统肉制品中。为此,本文结合国内外相关研究成果,对传统肉制品分类、主要存在的安全问题、天然提取物在传统肉制品中的应用研究及其作用机制进行概述,旨在为传统肉制品加工研究提供参考与借鉴。     

Rancidity development during frozen storage of mackerel (Scomber scombrus): effect of catching season and commercial presentation

Hydrolytic and oxidative rancidity development and its effect on quality loss were studied in frozen mackerel (Scomber scombrus) by biochemical and sensory indices. The effect of the lipid content on fish damage at a commercial freezer temperature (?20 °C) was studied for up to 12 months; thus, mackerel caught at two different times of the year (May and November) was checked, May being the period of minimum lipid content, while November is known to be the time of maximum lipid content. The study was also focused on two different kinds of fish products (whole fish and fillets). Increasing lipid hydrolysis was observed for all kinds of samples during the frozen storage; no differences (p >0.05) between whole fish and fillets were found for free fatty acid formation; however, mackerel from May showed a higher (p <0.05) hydrolysis development than its counterpart from November. Increasing lipid oxidation (peroxide value and thiobarbituric acid index) was observed for all kinds of samples during the frozen storage. Fillet lipid oxidation was found to be higher (p <0.05) than in whole fish. Fattier mackerel (November fish) showed a higher (p <0.05) oxidation development than its counterpart from May in the case of fillet products. Results of fluorescence assessment, related to interaction compound formation, proved to be higher (p <0.05) in fillets than in whole fish, although they were higher (p <0.05) in May samples. Sensory analysis corroborated the biochemical analyses, so that fillets showed a shorter shelf life (1 and 3 months for November and May fish, respectively) than their whole fish counterparts (5 months for November and May mackerel).     

Oil stability index correlated with sensory determination of oxidative stability in light-exposed soybean oil

Validity of the oil stability index (OSI) as an accelerated test of oxidative stability has been questioned because of its high holding temperature, 110°C, which may cause reactions that would not occur at lower temperatures. The purpose of this study was to characterize the usefulness of OSI as an accelerated oxidative stability test for oil of varying metal catalyst content by correlating OSI with the sensory induction period of light-exposed soybean oil. Five 400-g aliquots of soybean oil were placed in Erlenmeyer flasks and treated with increasing levels of a metal pro-oxidant, Cu²⁺ 2-ethylhexanoate. Pro-oxidant concentration ranged from 0 to 3.13×10⁻⁵ M. Five-gram aliquots were taken from duplicate flasks and immediately tested using the Oxidative Stability Instrument. Heating block temperature was 110°C. Sample flasks were then exposed to 800 footcandles of light and held at ambient temperature for 3 wk. One-gram aliquots were regularly withdrawn and evaluated for rancidity by 10 trained panelists to determine the sensory induction period of each sample. Aliquots were also taken to determine OSI of light-exposed oil samples. Sensory induction periods were correlated with OSI, resulting in a squared partial correlation coefficient (r ²) of 0.920. The r ² for OSI of light-exposed oil samples ranged from 0.897 to 0.979. OSI appears to be an acceptable accelerated method for measuring the oxidative stability of light-exposed soybean oil that varies in metal catalyst content.     

油脂水解罐保温层自燃现象探讨

油脂水解罐保温屋一般为不燃材料,但也可能因为设备按装不合理,使油脂落到保温层上酸败而自燃发生火灾事故,造成经济损失,本文对此自燃现象进行了分析探讨。