Precursors of 2-nonenals causing the cardboard off-flavour in butter oil

Methyl linoleate (ML) was autoxidised at room temperature in the dark. In comparison to hexanal, (E)- and (Z)-2-octenal, only very small amounts of (E)-2-nonenal were formed, indicating that linoleic acid was not an important precursor of the latter aldehyde. Palmitoleic acid in form of its methyl ester (MP) was studied as an alternative. Aroma extract dilution analysis revealed (E)-2-nonenal followed by (E)-2-octanal and (Z)-2-nonenal as the most potent odorants of autoxidised MP. Accordingly, in a butter oil sample in which the concentrations of either palmitoleic acid or linoleic acid were doubled, (E)-2-nonenal increased for 73 percent after addition of MP but only for 10 percent after that of ML. This difference indicates that the cardboard off-flavour of butter oil is mainly caused by an autoxidation of palmitoleic acid.     

Furan fatty acids in butter and butter oil

Summary Nine furan fatty acids (F-acids), among which 12,15-epoxy-13,14-dimethyleicosa-12,14-dienoic acid and 10,13-epoxy-11,12-dimethyloctadeca-10,12-dienoic acid predominated, were detected in butter and butter oil. The total amount of the F-acids in four butter samples varied between 116 and 476 mg/kg.

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Furanfettsäuren in Butter und Butterschmalz

Zusammensetzung Neun Furanfettsäuren (F-Säuren), unter denen die 12, 15-Epoxy-13,14-dimethyleicosa-12, 14-diensäure und die 10,13-Epoxy-11,12-dimethyloctadeca-10,12-diensäure dominierten, wurden in Butter und Butterschmalz nachgewiesen. In vier Butterproben variierte der Gehalt der F-Säuren zwischen 116 und 476 mg/kg.

     

葡萄酒微生物污染形成的不良风味物质研究进展

葡萄酒中不良风味物质的存在严重影响葡萄酒的品质,给生产带来较大的经济损失。对葡萄酒生产过程中由于微生物污染而形成的不良风味物质及主要预防措施进行主要介绍,包括葡萄原料被霉菌污染产生的蘑菇味和泥土味等物质;葡萄酒被酒香酵母污染产生的马厩味、酚味和鼠味等物质,被乳酸菌污染产生的黄油味、饭馊味和老鹳草味等物质,被醋酸菌污染产生的胶水味、煮苹果味和醋酸味等物质;橡木桶和软木塞被真菌污染产生的霉味、木塞味等物质。通过对微生物污染产生的不良风味物质特征及其主要防治措施进行系统梳理,为葡萄酒酿造生产提供借鉴。     

Butter and butter oil classification by PTR-MS

The potential of proton transfer reaction mass spectrometry (PTR-MS) as a tool for classification of milk fats was evaluated in relation to quality and authentication issues. Butters and butter oils were subjected to heat and off-flavouring treatments in order to create sensorially defective samples. The effect of the treatments was evaluated by means of PTR-MS analysis, sensory analysis and classical chemical analysis. Subsequently, partial least square-discriminant analysis models (PLS-DA) were fitted to predict the matrix (butter/butter oil) and the sensory grades of the samples from their PTR-MS data. Using a 10-fold cross-validation scheme, 84% of the samples were successfully classified into butter and butter oil classes. Regarding sensory quality, 89% of the samples were correctly classified. As the milk fats were fairly successfully classified by the combination of PTR-MS and PLS-DA, this combination seems a promising approach with potential applications in quality control and control of regulations.     

Oxidative stability of fish oil blended with butter.

The oxidative stability of fish oil blended with milk products was evaluated. Oxidation of the oil blend was determined by peroxide value and rancimat test. Improved oxidative stability was observed for fish oil blended with butter. Unsalted and salted butters showed no difference in improvement of effect on oxidative stability of fish oil. No influence on oxidative stability for the fish oil was observed with butter oil, which was the oil fraction of butter. These studies suggested that the improved oxidative stability of fish oil-butter blend was due to the hydrophilic fraction of butter and that butter could improve the oxidative stability of polyunsaturated oils such as fish oil.     

Fractionation of buffalo butter oil by supercritical carbon dioxide

Buffalo butter oil was fractionated by supercritical carbon dioxide into four fractions (F₁-F₄). Fractionation was performed at 50 and 70 °C over a pressure range of 10.9-40.1 MPa. Short chain fatty acids (C₄-C₈), medium chain fatty acids (C₁₀-C₁₄) and saturated fatty acids were decreased from F₁ to F₄, while long chain fatty acids (C₁₆-C_18:3) and unsaturated fatty acids were increased. Triacylglycerol molecular species exhibited a similar trend as fatty acids. Cholesterol was concentrated in F₁, and with increasing the fluid density, it decreased by more than 50% in F₄. Substantial changes occurred in the chemical composition of the fractions led to distinctive differences in their thermal profile and solid fat content. Fractions obtained in the initial stages of the fractionation exhibited lower melting behavior that obtained in the late stages.     

Volatile off-flavour compounds in desiccated coconut

Aliphatic methyl ketones and secondary alcohols have been isolated from desiccated coconut and shown to be responsible for the rancid off-flavour. Two series of compounds have been isolated. The series with an odd number of carbon atoms (C_5,7,9,11) comprising pentan-2-one, pentan-2-ol, heptan-2-one, heptan-2-ol, nonan-2-one, nonan-2-ol and undecan-2-one is derived from even chain fatty acids one carbon atom longer, present in the coconut oil by a modified β-oxidation due to growth of moulds. Heptan-2-one and nonan-2-one were present in the greatest concentration in the rancid coconut. These compounds gave an odour reminiscent of rancid almonds and turpentine respectively while heptan-2-ol and nonan-2-ol gave an odour similar to rancid coconut as well as a musty, stale odour. This type of off-flavour has been called ketonic rancidity and is an oxidative variation of the hydrolytic type of rancidity. The presence and origin of the even numbered series (C_6,8), hexan-2-one, hexan-2-ol and octan-2-one is discussed. The increase in C_5,6,7,8,9,11 oxidation products in the rancid samples occurred at the expense of C_8,10,12 short chain fatty acids.     

Digestive lipolysis in the preruminant calf. The abomasal hydrolysis of butter oil, coconut oil, palm oil and tallow

The effect of intramolecular short-chain fatty acids on the abomasal hydrolysis of long chain acyl ester bonds has been examined using four different fats. An evaluation of abomasal infusion of feeds as a technique to avoid hydrolysis of fat by salivary lipase has been made. Only calves considered to be typically functional preruminants were used for the investigations. Five preruminant calves each received five experimental milk feeds consisting of skim milk plus 3% of either butter oil, coconut oil, palm oil or tallow. All feeds were given by mouth but the feed that contained butter oil was also introduced directly into the abomasum via a simple cannula. In all cases, digesta leaving the abomasum were continuously sampled for 12 h via a re-entrant cannula in the proximal duodenum, anterior to the entry of the bile and pancreatic ducts. Butter oil given by mouth was hydrolysed to a greater extent than the other fats. This was due not only to the ease of liberation of the short chain fatty acids, but also to an enhanced liberation of longer chain acids when short chain acids are present in the triglyceride. Butter oil introduced directly into the abomasum of truly preruminant calves was not hydrolysed, suggesting that by using this technique studies could be made in vivo of the hydrolysis of fat by pancreatic lipase alone.     

香蕉粉及香蕉花生酱的加工工艺研究

该试验以香蕉和花生为原料对香蕉的护色、干燥方法及香蕉花生酱的加工工艺进行了研究。试验结果表明:香蕉去皮后,用0.2%柠檬酸 0.01%维生素C溶液浸泡10min护色、打浆,在75℃下热风干燥60min,得到香蕉粉,香蕉花生酱的最佳配方为花生酱73%、香蕉粉15%、单甘酯2%、蔗糖5%、植物油5%;香蕉花生酱适宜的杀菌条件为121℃,16min。     

花生酱蛋白饮料复配乳化增稠剂的研究

以花生酱、奶粉、白糖等原辅料制成的花生蛋白饮料为试样,进行不同均质压力、不同乳化增稠剂组合试验,考察其体系的稳定性。结果表明：采用均质温度70℃、均质压力40MPa,添加复配乳化增稠剂0.46%（聚甘油脂肪酸酯0.10%、硬脂酰乳酸钠0.03%、羧甲基纤维素钠0.03%、微晶纤维素0.25%、卡拉胶0.05%）时,产品的稳定效果最好。经常温贮存6个月观察,试样无沉淀,无明显脂肪上浮。     

Enzymatically modified tea seed oil as cocoa butter replacer in dark chocolate

Cocoa butter replacer (CBR) was prepared by enzymatic interesterification of hydrogenated and solid fraction (SF) of tea seed oil at weight percent ratio of 30:70, using sn‐1,3 specific lipase from Thermomyces lanuginosus. Dark chocolate samples were then prepared with the prepared CBR as a replacement for 5%, 10%, 15% and 20% of cocoa butter (CB) and the effect of the replacement on hardness (as a key quality factor in chocolate) of the chocolate samples was investigated. Results showed that chocolate samples containing 5% and 10% of interesterified sample (EIS), had the closer texture to that of CB chocolate than other samples. The solid fat content (SFC) profiles also revealed that blending 10% of EIS with CB in chocolate formulation dose not affect the sharp melting point of CB. Based on the results taken from bloom formation, polymorphic structure and sensory evaluation, adding up to 10% of EIS in chocolate formulation reduces the bloom development without adverse affecting the desirable β crystal formation and sensory qualities in the chocolate samples.     

香蕉粉及香蕉花生酱的加工工艺研究

该试验以香蕉和花生为原料，对香蕉的护色、干燥方法及香蕉花生酱的加工工艺进行了研究。试验结果表明：香蕉去皮后，用0．2％柠檬酸＋0．01％维生素C溶液浸泡10min护色、打浆，在75℃下热风干燥60min，得到香蕉粉；香蕉花生酱的最佳配方为花生酱73％、香蕉粉15％、单甘酯2％、蔗糖5％、植物油5％。     

Properties and stability of butter oil obtained from milk and yoghurt

The physical and chemical characteristics and thermal stability of butter oil produced from cow's milk by two different methods were studied. Butter oil samples from cow's milk were made (i) directly from milk and (ii) from yoghurt. Samples were autoxidized at 60, 70 and 80 degrees C in the dark and the reaction monitored by peroxide, thiobarbituric acid and free fatty acid values. Peroxide and thiobarbituric acid values increased as the temperature increased. The increase of the acid value was not significant. The thermal stability was highest in butter oil produced from yoghurt. Oxidative changes compared to hydrolytic changes are of greater significance in the thermal stability of butter oil samples. Arrhenius parameters and activation energies were calculated for the peroxide value data. The percent loss of linolenic acid was about 3 times faster than that of linoleic acid.     

Electrochemical determination of vitamin E in margarine, butter and palm oil.

A simple, rapid and reproducible method is described for the analysis of tocopherols in margarine, butter and palm oil. The method involves saponification, extraction of the unsaponifiable material and direct voltammetric determination. No separation technique is necessary. Two indicator electrodes, glassy carbon (GCE) and carbon paste (CPE), have been employed in this work, GCE in ethanol-benzene (2:1) medium and CPE in 75% ethanol. The CPE gives over ten times as much current as the GCE for a given tocopherol concentration. The GCE' high residual current in aqueous medium makes it impractical in 75% aqueous ethanol and the CPE' solubility in benzene restricts its usage in ethanol-benzene medium. Slight turbidity does occur sometimes when the unsaponifiable material of the samples is dissolved in 75% ethanol but this seems not to interfere in subsequent analysis. Increase in ethanol content to 90% gives a clearer solution and higher background, but no appreciable difference in the results. The results obtained by use of both electrodes are given and shown to be in close agreement with previously published results.     

Determination of food contamination by mineral oil material from printed cardboard using on-line coupled LC-GC-FID

 Inks used for printing paper and cardboard are dispersions of synthetic organic pigments in a bonding agent system built up essentially of resins, vegetable oils and high-boiling-point mineral oil products (b.p. >250°C). The proportion of mineral oil material in the ink ranges between 20 and 30%. The more volatile mineral oil components slowly evaporate from the printed cardboard box and may migrate into the food product. They contaminated cereals and dry baby-food products at concentrations between 10 and 150 mg/kg. Received: 27 January 1997     

复配抗氧化剂对低能量类可可脂抗氧化作用的研究

采用Schaal烘箱加速氧化法,以过氧化值为评价指标,研究了二丁基羟基甲苯、植酸、维生素E三种抗氧化剂对低能量类可可脂的抗氧化效果。采用响应曲面法优化并确定了复配抗氧化剂的最优配方,结果表明：复配抗氧化剂的最优组成比例为BHT0.11‰,PA0.11‰,VE0.13‰,复配抗氧化剂各组分间具有显著的协同增效作用。通过比较最优复配抗氧化剂与单一抗氧化剂对低能量类可可脂的抗氧化效果,得出其抗氧化活性明显优于单一抗氧化剂。     

全料花生酱制备花生乳的生产工艺研究

研究以全料花生酱为主要原料制备花生乳生产过程的最佳工艺条件.采用对照试验对影响工艺的主要因素进行研究.结果表明:20 μM以下的花生酱配合使用0.25%复合稳定剂SA-5A(花生酱),65～75℃,经过两次均质:25～30 MPa/40～50 MPa,121～127 ℃/15 min高压灭菌,可制备成稳定的花生乳饮料.     

外卖食品包装用防水防油卡纸的制备及性能研究

为开发外卖食品包装容器,以白卡纸为基材,通过涂覆羧甲基壳聚糖(CMCS)溶液和聚乳酸(PLA)溶液制备防水防油纸,从而赋予卡纸防水和耐油性能,力学性能相比原纸也有所改善.本文研究了CMCS和PLA涂布量以及风干时间对卡纸的阻隔性和力学性能的影响.结果表明:涂布5％(wt)、涂布量为3.06 g/m2的CMCS烘干后,再...