CHANGES IN EDIBLE FATS AND OILS DURING PROCESSING

Fats and oils are essential nutrients for humans and animals. They are the most concentrated source of energy by contributing 9 kcal/g lipid, serve as carrier of fatsoluble vitamins and provide essential fatty acids. Fats and oils give flavor and taste to the foods, and also serve as a heat transfer medium. The lipid molecules undergo different chemical reactions during processing starting from separation from their raw sources to the storage. Chemical changes of lipids occurring during processing are numerous and can be desirable, undesirable, of questionable consequence, or a combination thereof. This review discusses the chemical changes of lipids that occur during various types of processing. Specific changes in the minor constituents of lipids are also included.     

AUTHENTICITY ASSESSMENT OF FATS AND OILS

Authenticity is an important issue for the food industry due to legal compliance, economic reasons (right goods for the right price), guarantee of a constant well-defined quality, use of safe ingredients (no hazardous substitutes), and religious reasons (halal, kosher). This report gives an extensive overview on the authenticity assessment of oils and fats for food products and summarizes the principal techniques useful for this assessment. Scope and limits of different analytical tools are discussed.     

AUTHENTICITY ASSESSMENT OF FATS AND OILS

Authenticity is an important issue for the food industry due to legal compliance, economic reasons (right goods for the right price), guarantee of a constant well-defined quality, use of safe ingredients (no hazardous substitutes), and religious reasons (halal, kosher). This report gives an extensive overview on the authenticity assessment of oils and fats for food products and summarizes the principal techniques useful for this assessment. Scope and limits of different analytical tools are discussed.     

茶多酚对主要食用油脂抗氧化作用的研究

采用不同浓度茶多酚对几种主要食用油脂进行处理试验，筛选出了能显示出较强的抗氧化效能（300～500）×10~（－6）浓度。增效剂Vc的应用，在猪油上能使茶多酚抗氧化效能的保护系数增加0．13。但对菜油、花生油无明显效果。     

INFRARED SPECTROSCOPIC DETERMINATION OF DEGREE OF UNSATURATION OF FATS AND OILS

SUMMARY– Infrared spectra of various fats and oils were determined. Ratios of absorbance at 3.3μ (olefinic C—H stretching band) to absorbance of other characteristic triglyceride absorption bands were calculated. Relationships between these ratios and unsaturation, as estimated by iodine value, were determined. Analyses of 25 fats and oils showed that the ratio of absorbance at 3.3μ to absorbance at 3.5μ (aliphatic C—H stretching band) and iodine value were linearly related and exhibited a correlation coefficient of 0.98. Estimation of degree of unsaturation of 19 additional fats and oils revealed an average deviation of ± 0.97 iodine value units or ± 1.12% between measured values and values calculated from infrared absorption patterns.     

CHARACTERIZING QUALITY OF RENDERED DUCK FAT COMPARED TO OTHER FATS AND OILS

The characteristics of rendered duck fat (RDF) were compared to commercial sources of soybean oil, lard, tallow, butter and olive oil. RDF was highly susceptible to lipid oxidation during storage compared to the other fats and oils. However, 0.005% tert‐butyl hydroquinone delayed the onset of lipid oxidation to an extent that was comparable to the lag phase observed in the commercial fats and oils. Positive attributes of RDF included a relatively high oleic acid content and low saturated fat content. Undesirable attributes of RDF included a lack of conjugated linoleic acid (CLA) and intermediate levels of trans fatty acids (TFA) compared to the other lipid sources. Decreasing the time and temperature of rendering decreased the TFA content in RDF. Around one‐half of the TFA content in RDF was vaccenic acid which is converted to CLA after ingestion.     

过路黄在食用油脂中抗氧化作用的研究

经过实验,首次筛选出中草药——过路黄(Lysimachia christinae Hance)在油脂中具有较强的抗氧化作用。过路黄在我国分布很广,并且价廉、无毒,作为油脂抗氧化剂具有一定的社会和经济效益.过路黄的乙醚提取物在菜籽高级烹调油中的抗氧化作用显著高于α-VE 及人工合成抗氧化剂 BHT 的作用,在猪油中也有较强的抗氧化作用;研究了增效剂柠檬酸对提取物的增效作用;采用化学显色法初步推断其有效的抗氧成分为酚类、黄酮类及甾醇类化合物.     

四种藏药对食用油脂抗氧化性的初步研究

在五种食用油脂中加入适量的高原蚤缀、刺芒龙胆、黄花棘豆、风毛菊的乙醇提取物,通过测定不同时期的POV,研究了以上四种藏药对食用油脂的抗氧化作用,试验结果表明,四种藏药的乙醇提取物均对五种食用油脂有一定的抗氧化作用。     

EFFECTS OF HYDROCOLLOIDS AND ASPARTAME ON SENSORY VISCOSITY AND SWEETNESS OF LOW CALORIE PEACH NECTARS

Effects were studied of interactions between each of three hydrocolloids-xanthan gum, guar gum and methylcellulose- and aspartame on sweetness intensity and sensory viscosity of low-calorie peach nectars (60% fruit purée with no sucrose added). The flows of the nectars were characterized as near Newtonian without hydrocolloids, as Bingham plastic at lower hydrocolloids concentrations and as pseudoplastic at higher concentrations (Ostwald flow for guar and methylcellulose, and Herschel-Bulkley for xanthan). Hydrocolloids concentrations were selected to cover viscosity range of commercial whole nectars: 0.10 and 0.20% xanthan or guar, and 0.15 and 0.30% methylcellulose. Aspartame concentrations tested were derived from the calculation of equisweet concentration as referred to a control nectar sample with sucrose (14°Brix) and of the upper and lower limen value: 0.216, 0.360 (equisweet), 0.502, and 0.644 g/L. Addition of either guar or methylcellulose did not alter the perceived sweetness in aspartame-sweetened peach nectars. Xanthan addition, even at 0.10%, significantly lowered sweetness of samples sweetened with the highest aspartame concentration (0.644 g/L). Addition of aspartame did not modify the perceived viscosity in samples thickened with either xanthan or guar gums. At all methylcellulose concentrations tested, samples with the lowest aspartame concentration (0.216 g/L) were perceived as less viscous.     

RECENT DEVELOPMENTS IN LOW TEMPERATURE STEAM DISTILLATION OF HOP OIL

Improved equipment for producing hop oil emulsions by steam distillation at low temperature allows easier operation. In addition, a lower operating pressure results in a more efficient and less costly extraction. Emulsions obtained from similar batches of hops using both the new and older designs of hop extractors could not be distinguished by instrumental means or by a multiple comparison taste test.     

国际工业金刚石行业发展形势与动态

进入21世纪,国际工业金刚石行业发生了一些重大事件。DeBeers是一个具有百余年历史的国际著名大企业,于2002年10月1日更名为ElementSix(元素6)。该公司以巨大的能量、速度和积极的思想取得了全球金刚石行业的主导地位,并将其未来业务的发展定位在富于想像力的和与众不同的方向。GE公司超硬材料部是第一个合成人造金刚石的生产部门,也是世界上最主要的人造金刚石、立方氮化硼和聚晶金刚石制品的生产厂家,而今却被一家私人投资机构所收购。人造金刚石的问世已过去半个世纪,展望工业金刚石行业今后的发展,应该是扩大人造金刚石和其它超硬材料的规格品种,同时探索新型超硬材料并开拓其应用领域。     

SALT SUBSTITUTES IN RESTRUCTURED HAM

Potassium chloride, magnesium chloride, calcium chloride and magnesium sulfate were incorporated to individually substitute 50% of the ionic strength of the sodium chloride in restructured ham. The calcium chloride, magnesium chloride and magnesium sulfate treatments resulted in significantly lower cook yields while those samples with calcium chloride exhibited significantly higher thiobarbituric acid (TBA) values compared to the four other treatments. The calcium chloride and magnesium sulfate treatments produced hams that had significantly different "L", "a", and "b" values compared with the control. The total lipid and cholesterol contents of the various treatments were not significantly different.     

DEVELOPMENTS IN THE MALTING AND BREWING INDUSTRIES IN GERMANY*

Changes in the methods of malting and brewing which have been introduced into the industry in Germany are reviewed. In general, these changes have allowed economy in malting time and in time required for fermentation and maturation, without having any deleterious effect on beer quality. Mashing, by the decoction system, and wort boiling have not altered greatly though closed cooling systems are now more general. All these modifications of procedure have to be geared not only to the changing drinking habits of the public but also to the need to supply a wide range of different products.