反式脂肪酸安全问题辨析

针对我国反式脂肪酸安全问题宣传中存在的问题,从氢化油、植物黄油等产品的定义和发展历史出发,释义了反式脂肪酸,阐述了反式脂肪酸与人体健康的关系,并初步评估了我国民众反式脂肪酸摄入情况,旨在开展对反式脂肪酸安全问题的科学理性讨论,普及和提高公众对反式脂肪酸问题的科学理性认识,指导食品消费和生产。     

Influence of Fat and Emulsifier Content on Volatile Release of Butter Aroma Used in Water Phase and Physical Attributes of Model Margarines

Margarines are water‐in‐oil (W/O) emulsion‐type products produced with butter aroma. The aim of this study is to investigate the volatile release of the butter aroma compounds used in the water phase of model margarine and sensory properties influenced by the change of fat and emulsifier. A headspace/solid phase microextraction/gas chromatography/mass spectrometry (HS/SPME/GC/MS) system is used for the identification of the volatile compounds. It is determined that high fat content in model margarine samples results in an increase in the release of both 2,3‐butandione and butanoic acid. On the other hand, an increase in fat content reduces the release of butanoic acid ethyl ester and vanillin. In addition, an increase in the emulsifier content of the model margarines results in a decrease in butanoic acid ethyl ester release. The model margarines with 80% fat content have the highest hardness and storage modulus (G′) values. The perception of butter aroma and taste are more intense in high‐fat margarine samples, while fruity aroma and taste, vanilla aroma, and taste perception are higher in low‐fat margarine samples. However, emulsifier content does not affect the sensory properties of the model margarines. Practical Applications: Decreasing high fat content food intake has become increasingly popular among consumers. Thus, in order to meet consumer demands, manufacturers have begun to reduce the fat content of the foods they produce. However, the flavor properties of a product can change as a consequence of fat content reduction. In order to produce a product in accordance with the properties demanded by the consumer, the change in the flavor of that product should be foreseen depending on the change in fat content. This study aimed to determine the volatile compound release and sensory properties of margarine samples due to fat and emulsifier changes. The findings of this study are a guide for the production of low‐fat products.     

Formation of the intense flavor compoundtrans-4,5-epoxy-(E)-2-decenal in thermally treated fats

Thermal degradation of several possible precursors of the intense flavor compoundtrans-4,5-epoxy-(E)-2-decenal in model experiments revealed that the odorant is formed in significant yields from 13-hydroperoxy-9,11-octadecadienoic acid (13-HPOD) and 9-hydroperoxy-10,12-octadecadienoic acid (9-HPOD). Of these hydroperoxides, arising in equal amounts during autoxidation of linoleic acid, the 9-HPOD was established as the more effective precursor. The key intermediates in the generation of the epoxyaldehyde were found to be 2,4-decadienal, arising from 9-HPOD, and 12,13-epoxy-9-hydroperoxy-10-octadecenoic acid, a degradation product of 13-HPOD. Isolation and characterization of the precursors from a baking margarine confirmed glycerine-bound 9- and 13-HPOD as the intermediates in the formation of the epoxyaldehyde during heating of fats that contain linoleic acid.     

Composition,physical and textural characteristics of soft (tub) margarines

Soft (tub) margarines were analyzed for fatty acid,trans and polyunsaturated fatty acid (PUFA) content. Soybean and sunflower-palm kernel-palm margarines contained high levels ofcis-cis methylene interrupted (CCMI)-PUFA. Canola and canola-palm products contained the lowest amounts of saturated fatty acids. Polymorphic forms of the crystals were as follows: soybean beta prime, canola beta, canola-palm and a sunflower-palm kernel-palm—a mixture of beta and beta prime. Dropping points of the fats ranged from 27.3 to 34.2°C. Softening points of the products were higher especially for margarines that existed in the beta form. Texture was determined by cone penetrometer, constant speed compression and penetration. Soybean margarines were generally most resistant to deformation. The solid fat content (SFC) of the “whole” margarines as determined by the Bruker Minispec was found to be slightly lower than that of the separated fat (AOCS-method) at 10°C. Correlation of values within the textural methods was significant (P<.01), but not between the texture and SFC of the product which means that the nature of the crystal network also plays a role in texture.     

Positional and geometrical isomers of linoleic acid in partially hydrogenated oils

The geometrical and positional isomers of linoleic acid of a partially hydrogenated canola oil-based spread were isolated and identified. Through partial hydrazine reduction and mass spectral studies,cis-9,trans-13 octadecadienoic acid was identified as the major isomer. Other quantitatively important isomers characterized werecis-9,trans-12;trans-9,cis-12 andcis-9,cis-15. These four were also the major isomers in margarine based on common vegetable oils. A number of minor isomers were detected and some structures identified weretrans-9,trans-12;trans-8,cis-12;trans-8,cis-13;cis-8,cis-13;trans-9,cis-15;trans-10,cis-15 andcis-9,cis-13. The proportions of the various isomers are given for some margarines in the Canadian retail market. The amounts oftrans-9,trans-12 isomer in Canadian margarines were generally below 0.5% of the total fatty acids.     

13C nuclear magnetic resonance spectroscopic analysis of the triacylglycerol composition of some margarines

The triacylglycerol fraction of three samples of margarine, namely “Flora” (Holland), “Kaliakra” (Bulgaria), and “Corona” (Holland), were studied by¹³C nuclear magnetic resonance spectroscopy. By examining the various carbon chemical shifts of the saturated and unsaturated carbon nuclei, “Flora” margarine was shown to contain a mixture of hydrogenated and unhydrogenated vegetable oils. This technique allowed all major acyl groups (saturated, oleate, linoleate, and linolenate) and minor acyl components [different positional isomers of long-chain (E)- and (Z)-monoenoic moieties, arising as by-products during catalytic hydrogenation] to be identified. The amount of each fatty acid present in the margarine was also estimated from the relative intensities of the corresponding signals. “Kaliakra” margarine consisted of a blend of unhydrogenated natural fats and oils that contained saturated fatty acids, oleate, and linoleate. There were no signs in the spectrum of “Kaliakra” of any (E)-isomers, nor signals associated with positional unsaturated acyl groups (other than oleate and linoleate). The sample of “Corona” margarine consisted of a mixture of hydrogenated and unhydrogenated vegetable oils and butter (1.3%). The presence of butter in this sample was identified by the characteristic carbon shifts of the C-1 to C-4 carbon atoms of butyrate. The distribution of the fatty acids on the glycerol “backbone” also was estimated by this technique.     

Attraction responses of the American cockroach to synthetic periplanone-B

Synthetic periplanone-B has been shown not only to be a sex excitant to malePeriplaneta americana by bioassay in the laboratory but also an attractant pheromone by field tests in a rice storage house in Taipei. During both summer and winter months, it attracted signincantly more adult males into the traps used in the experiments than adult females. There is a statistically significant increase in the sex ratio (male-female) of the trapped adults with increase in periplanone-B used. An attempt has been made to explain the trapping of females and nymphs in addition to males by the chemicals used in our tests.     

Oxidative stability,structural, and textural properties of margarine enriched with Moringa oleifera leaves extract

Consumer's demand for clean label food ingredients has driven the development of alternative food additives. This study falls within this challenge through valorization of Moringa oleifera leaves grown in Algeria as a natural antioxidant. A methanolic M. oleifera leaves extract (MOLE) was prepared and included in margarine at various levels (400, 600, and 800 ppm) and was compared to vitamin E and a margarine without antioxidants. The effect of addition of MOLE on margarine quality was studied by means of its oxidative stability, structural, textural properties, color, and aroma fingerprint. It was shown that addition of MOLE to margarine increased resistance towards oxidation, showing a higher antioxidant capacity as compared to margarine with vitamin E or without antioxidants. Moreover, addition of MOLE decreased water droplet size, which is desirable from a microbiological viewpoint since it could extend margarine's shelf life. Furthermore, addition of MOLE leads to the formation of smaller fat crystals, resulting in different fat network formation, which could be the cause of the increase in hardness seen in these margarines. Regarding sensorial effects, MOLE addition led to a significant darkening of the margarine and increase yellowness. Moreover, the aroma fingerprint showed that addition of MOLE modified the aroma fingerprint of this product.     

The Role of Water in Protection Against Thermal Deterioration of Liquid Margarine

The thermal stability of liquid margarine and vegetable oils was investigated by measuring the oxidative stability index (OSI) at temperatures ranging from 90 to 180 °C, whereas total polar compounds (TPC) and tocopherols (vitamin E) were measured during heating at 180 °C in frying trays. Results showed that the OSI of liquid margarine was in the same range as the OSI of vegetable oils at lower temperatures, but at 160 and 180 °C, liquid margarine had significantly higher thermal stability, close to that observed for hard margarine and butter. The increased stability was confirmed by lower levels of TPC and a smaller relative reduction in vitamin E content during heating. Variations between different vegetable oils could partly be explained by differences in degree of saturation and level of vitamin E, with high oleic sunflower oil being the most stable oil at all temperatures. The water in liquid margarine vaporized within 1.5 min at 160 °C, and it is hypothesized that volatile pro‐oxidants are removed with the water, inducing a delay in deterioration. The results indicate a role for water in preventing lipid oxidation and decomposition in fat emulsion products at 160–180 °C, suggesting that liquid margarine, low in saturated fat, may be the healthier and preferable alternative for pan‐frying compared to other liquid vegetable oils.     

Physicochemical and textural properties of puff pastry margarines

In this paper some physicochemical and textural characteristics of four puff pastry margarines are defined: MLT1 and MLT2 with low trans fatty acid (TFA) content, MLT3 with relatively low and MLT4 with high TFA content. Analyzing the solid trigliceride content (SFC), the crystallization kinetics in isothermal conditions and the margarine firmness, it is determined whether the technological characteristics of margarines (which are very important for puff pastry quality) are significantly changed due to TFA decrease in margarines. The highest SFC at 10, 20, 25 i 30°C have samples MLT1 and MLT4. Despite of significant differences in fatty acid composition of these margarines, SFC content at temperatures at 20, 25, and 30°C do not differ significantly, at the level of significance of 95% (p>0.05). The SFC of MLT1 and MLT2 samples, which have practically the same fatty acid composition at every investigated temperature, statistically have significant difference (p<0.05). The crystallization kinetics are in the range from 2.6 to 10.1% per min. The significance of the induction period at every observed samples is negligible. The average firmness of margarine samples MLT1, MLT2, MLT3, and MLT4 at 20, 25, and 30°C is significantly different (p<0.05). The firmness changes of the samples MLT1 and MLT2 in the most important temperature interval for puff pastry production (between 20 and 30°C) are at level of 5 to 25%, and for margarine samples MLT3 and MLT4 these values reach even 70%.