Physico-chemical and rheological properties of full fat and low fat edam cheeses

Low fat (17% fat) and full fat (27% fat) Edam cheese manufactured and aged up to 6 months at 5 °C were studies. The objective was to investigate the impact of fat on the physico-chemical and rheological properties of Edam cheese. Total soluble nitrogen in aqueous extract (TNAE), protein nitrogen in aqueous extract (Pro-NAE) and peptide nitrogen in aqueous extract (Pep-NAE) were determined by the Kjeldahl method. Low fat Edam (LFE) had markedly higher Pep-NAE than full fat Edam (FFE). The rheological properties were determined using an Instron Universal Testing Machine. LFE had significantly higher stress values than FFE, indicating hard and rubbery texture. Furthermore, LFE had lower strain values indicating crumbliness.     

绵羊脂与山羊脂品质特性差异分析

旨在为羊脂的精深加工提供参考,以绵羊脂和山羊脂为研究对象,分析了两种羊脂理化性质、营养品质与风味特性的差异。两种羊脂的理化性质按国标方法测定,脂肪酸组成及胆固醇的含量由气相色谱测定,甘油三酯组成由超高效液相色谱联用Q-Exactive HFX高分辨轨道阱质谱仪测定,挥发性风味物质采用顶空-固相微萃取结合全二维气相色谱-飞行时间质谱法测定。结果表明：绵羊脂与山羊脂均检测出22种脂肪酸,主要脂肪酸均为C16∶0、C18∶1n-9c和C18∶0,饱和脂肪酸含量分别为38.69、54.39 g/100 g;两种羊脂均检测出30种甘油三酯,绵羊脂中三饱和、单不饱和、单饱和与三不饱和脂肪酸甘油三酯含量分别占总甘油三酯含量的2.66%、26.76%、36.89%和33.69%,山羊脂的分别为15.87%、45.59%、26.47%和12.07%;绵羊脂与山羊脂鉴定出挥发性化合物共95种,含量分别为122.11、32.68μg/g,关键风味化合物34种,其中癸醛、6-甲基-2-庚酮、乙酸戊酯、2-正丁基呋喃仅在绵羊脂中被检测出,3-甲基-2-戊酮仅在山羊脂中被检测出,主成分分析表明两种羊脂可完全分离,...     

肉类脂肪与胆固醇

作为人体六大营养要素之一的脂肪,特别是肉类脂肪,现在几乎成了胆固醇增高、高血脂、动脉粥样硬化、高血压、冠心病的代名词.     

Interactions of milk fat and milk fat fractions with confectionery fats

The objectives of this study were to provide a better understanding of the effects of triacylglycerol (TAG) and non-TAG components (minor lipids) of milk fat on phase and crystallization behavior of binary mixtures of palm kernel oil (PKO) and the physical properties of corresponding compound coatings. Binary mixtures of a fractionated PKO with the different milk fats were examined for melting profiles, crystallization kinetics, and crystalline microstructures, and polymorphic changes during storage. Compound coatings were made with equivalent binary fat mixtures and measured for hardness and bloom formation. Milk fat and milk fat fractions affected crystallization rates of fractionated PKO, depending on the melting point of the fat. High-melting components resulted in more rapid crystallization, whereas the original milk fat and low-melting components inhibited crystallization. The crystal structure (e.g., number, size, shape) of the PKO crystals was influenced significantly by the addition of milk fat fractions and was influenced by the presence or absence of the minor lipids in milk fat. Milk fat and milk fat fractions had a softening effect on fractionated PKO, which was apparent in the binary mixtures as well as the compound coatings. In general, as the solid fat content (at 25 degrees C) of the binary mixtures increased, the hardness of the respective coatings increased. This also was related to an increased rate of bloom formation during storage.     

天然代脂品 市场新宠儿

<正> 我国的肥胖症人群比率正在迅速增长,据悉,这种文明病已为我国带来7,000多万名病患者,而在城市地区的肥胖症比例更超过17%。相比于20世纪80年代,中小学生超重案例只有10%,10年后,该比例已上升至20%。现在人们对营养和健康认识日益加深,增强了消费者对低脂低热食品的需求。健康专家已经证实过量的摄入脂肪,尤其是饱和脂肪的摄入,是导致文明病的主要元凶。 美国心脏协会推荐,如每日从脂肪摄取的热量减少至总热量摄入量的30%,同时增加复合碳水化合物的摄入量,能有效降低罹患心脏病的可能性。 目前,代脂品已成为食品加工业常用的食品脂肪取代方案,而且不断推陈出     

Transfer of dietary zinc and fat to milk--evaluation of milk fat quality, milk fat precursors, and mastitis indicators

The present study demonstrated that the zinc concentration in bovine milk and blood plasma is significantly affected by the intake of saturated fat supplements. Sixteen Holstein cows were used in a 4 × 4 Latin square design with 4 periods of 12 d, and 4 dietary treatments were conducted. A total mixed ration based on corn silage, grass-clover silages, and pelleted sugar beet pulp was used on all treatments. A high de novo milk fat diet was formulated by adding rapeseed meal and molasses in the total mixed ration [39 mg of Zn/kg of dry matter (DM)], and a low de novo diet by adding saturated fat, fat-rich rapeseed cake, and corn (34 mg of Zn/kg of DM). Dietary Zn levels were increased by addition of ZnO to 83 and 80 mg of Zn/kg of DM. Treatments did not affect daily DM intake, or yield of energy-corrected milk, milk fat, or milk protein. The high de novo diet significantly increased milk fat percentage and milk content of fatty acids with chain length from C6 to C16, and decreased content of C18 and C18:1. Treatments did not influence milk free fatty acids at 4°C at 0 or 28 h after milking. The average diameter of milk fat globules was significantly greater in milk from cows offered low de novo diets. Furthermore, the low de novo diet significantly increased the concentration of nonesterified fatty acids and d-β-hydroxybutyrate in blood plasma, the latter was also increased in milk. Treatments did not affect the enzyme activity of lactate dehydrogenase and N-acetyl-β-d-glucosaminidase in milk or the activity of isocitrate dehydrogenase and malate dehydrogenase in blood plasma. The low de novo diet significantly increased plasma Zn and milk Zn content, whereas dietary Zn level did not in itself influence these parameters. This indicates that the transfer of fat from diet to milk might facilitate transfer of Zn from diet to milk.     

Controlling fat bloom formation in chocolate – Impact of milk fat on microstructure and fat phase crystallisation

The partial replacement of cocoa butter (CB) with milk fat (MF) strongly influences micro-scale topographic evolution and fat phase crystallisation in milk chocolate. Adding MF reduces the incidence of large surface crystals and the number and diameter of amorphous, welled CB deposits (‘cones’), with a concurrent decrease in initial surface roughness (p < 0.05) and rate of surface coarsening. Presence of MF also slows the solidification of the cones into disorganised crystalline masses. Finally, MF reduces the initial solid fat content, and slows the rate of change in whiteness index, as well as the form V to VI polymorphic transition. Fat crystal growth is accelerated by repeated temperature-cycling (26–29 °C) compared to isothermal conditioning (26 °C). However, cone hardening occurs more rapidly when isothermally-stored. Irrespective of fat composition and storage conditions, fat crystal growth, welling and ultimately fat bloom begin only at specific locations on the chocolate surface, suggesting that chocolate’s microstructural heterogeneity is responsible for distinct surface fat crystallisation pathways.     

Detection of foreign fat in milk fat II. Quantitative evaluation of foreign fat mixtures

Summary Based on gas chromatographic analysis of triacylglycerol composition of 755 different milk fat samples, formulae were derived from statistical evaluations. They allow quantitative detection of greatly differing foreign fat additions to milk fat by insertig defined triacylglycerol contents of a fat to be analyzed. Further, any combination of different foreign fats, consisting. e.g., of a mixture of medium- and long-chain triacylglycerols can be detected by using this method. For the widely varying foreign fat mixtures, limits of detection between 2–5% were established. For 23 different additions (3–15%) of individual vegetable foreign fats or animal depot fats, as well as for 33 foreign fat mixtures (4–7% addition) added to unknown milk fats from varying feeding periods, absolute mean deviations of 0.7–0.8% were found.

---

Fremdfettnachweis in Milchfett II. Quantitative Bestimmung von Fremdfettgemischen

Zusammenfassung Basierend auf der gaschromatographisch bestimmten Triglyceridzusammensetzung von 755 verschiedenen Milchfettproben sind mit statistischen Auswertungen Triglyceridformeln abgeleitet worden, die durch das Einsetzen bestimmter Triglyceridanteile eines zu prüfenden Fettes den quantitativen Nachweis verschiedenster Fremdfettzusätze zum Milchfett zulassen. Darüber hinaus können mit der Methode auch beliebige Kombinationen verschiedener Fremdfette, die z. B. aus einer Mischung von mittel- und langkettigen Triglyceriden bestehen, nachgewiesen werden. Für die verschiedensten Fremdfettgemische ergaben sich Nachweisgrenzen von 2–5%. Bei 23 unterschiedlichen Zusätzen (3–15%) einzelner pflanzlicher Fremdfette oder von tierischen Depotfetten sowie von 33 Fremdfettgemischen (4–7% Zusatz) zu unbekannten Milchfetten aus verschiedensten Fütterungsperioden wurden absolute mittlere Abweichungen von 0,7–0,8% festgestellt.

     

Analysis of major proteins and fat fractions associated with mare's milk fat globules

Although several studies have aimed to identify mare's milk proteins, only the major whey proteins and some caseins have yet been characterized. Incomplete sequencing of the equine genome and the difficulty of recovering highly hydrophobic proteins mean that little is known to date about the proteins associated with milk fat globules, which have been shown to play an important role in newborns' defense mechanisms. The fat fraction, in particular the distribution of unsaturated fatty acids, has been more extensively studied, but complex lipids are only partially elucidated. This study reports a 2-DE approach combined with a powerful method for de novo protein sequencing, and quali-quantitative data on complex lipid composition determined by high performance TLC (HPTLC) and GC. The presence in mare's milk of long-chain highly unsaturated fatty acids, and the evidence of close similarity between equine and human milk fat globule membrane proteins, support the use of mare's milk for human nutrition.     

Impact of cream washing on fat globules and milk fat globule membrane proteins

Milk proteins, contained within the aqueous phase surrounding fat globules, should be removed before analysis of the composition of the native milk fat globule membrane (MFGM). The effect of the conditions applied during washing of cream on MFGM integrity has not been fully studied, and factors potentially effecting a modification of MFGM structure have not been systematically assessed so far. In this study, a cream separator was used to investigate the impact of cream washing on milk fat globule stability and the corresponding loss of MFGM proteins. Flow velocity, fat content, and type of washing solution were varied. Particle size measurements and protein analyses were carried out after each washing step to determine fat globule coalescence, removal of skim milk proteins, and efficiency of MFGM isolation. Significant differences in fat globule stability and protein amount in the MFGM isolates were measured using different washing conditions.     

Precision and sensitivity of a test for vegetable fat adulteration of milk fat

A test for routine screening of Mozzarella cheese and butter for vegetable fat adulteration is described. Fat is extracted and saponified. The potassium salts of the fatty acids are measured through direct gas chromatographic analysis. A ratio, calculated from the concentrations of butyric and oleic acids, is used to evaluate the purity of a sample. The test offers good precision and can detect less than 10% partially hydrogenated vegetable fat.     

Rheological properties of ice cream mixes and frozen ice creams containing fat and fat replacers

Ice cream mixes and frozen ice creams at milk fat levels of 12%, 8%, 6%, 6% plus a protein-based fat replacer, and 6% plus a carbohydrate-based fat replacer were evaluated for viscoelastic properties by dynamic testing with sinusoidal oscillatory tests at various frequencies. The storage modulus (G'), loss modulus (G"), and tan delta (G"/G') were calculated for all the treatments to determine changes in the viscous and elastic properties of the mixes and frozen ice creams due to fat content. In ice cream mixes, G' and G" exhibited a strong frequency dependence. The G" was higher than G' throughout the frequency range (1 to 8 Hz) examined, without any crossover, except for the 12% mix. Elastic properties of the ice cream mixes decreased as fat content decreased. Tan delta values indicated that fat replacers did not enhance the elastic properties of the ice cream mixes. In all frozen ice creams, G' and G" again showed a frequency dependence throughout the range tested (0.5 to 10 Hz). The amount of fat in ice creams and the degree of fat destabilization affected the elasticity in the frozen product. Even though the ice creams did not have significant elastic properties, when compared as a group the samples with higher fat content had higher elastic properties. The addition of protein-based and carbohydrate-based fat replacers did not enhance the elastic properties of the ice creams but did increase the viscous properties.     

Mutual effect of fat and β-carotene on fat crystal network structure and carotenoid bleaching

In this study the mutual effect of fat type and β-carotene on fat crystallization behavior and carotenoid bleaching was investigated. To this aim, β-carotene was added to tripalmitin (PPP), tristearin (SSS) and saturated monoglycerides (MG). Phase transition properties of fats with and without β-carotene were studied by differential scanning calorimetry, synchrotron X-ray diffraction and polarized light microscopy. The color fading of β-carotene containing fat matrices was followed by measuring color changes during storage at 20 °C.Structural information acquired at different length scales highlighted that the presence of β-carotene in fats greatly affected crystal morphology, crystal network structure and thermal properties of the lipid matrices. Depending on fats molecular characteristics, β-carotene participated (PPP and SSS) or withdrew (MG) from the fat crystallization. The presence of β-carotene probably altered the triacylglycerol crystal morphology through its incorporation into the solid phase. Contrarily, β-carotene formed clusters inside the solid matrix when added to MG. Results appear of considerable interest in the attempt to improve the stability of β-carotene in lipid containing foods as well as to design efficient delivery systems, for which the choice of the lipid carrier could be crucial. In fact, preliminary results showed that the kinetics of β-carotene bleaching were higher in PPP and SSS than in MG, suggesting that β-carotene location inside the crystal network as well as lipid structure organization might affect the carotenoid chemical stability.     

Interaction between plastics packaging materials and foodstuffs with different fat content and fat release properties

The migration of an addictive (phenolic antioxidant) from different types of plastic food packaging materials (low density polyethylene [LDPE], high density polyethylene [HDPE], polypropylene [PP], acrylonitrile-butadiene-styrene [ABS] and high-impact polystyrene [SB]) into low-calorie (reduced fat) foodstuffs has been determined under normal storage conditions, and shown in most cases to be equivalent to migration into normal foodstuffs. Certain exceptions are discussed and related to the fat-release properties of the particular foodstuffs. Additive transfer into low-calorie products, as well as into emulsions of fat and water, has been compared with that into aqueous acetic acid and test fat HB 307 under normal storage conditions and after 10 days at 40 degrees C. The transfer of antioxidant from plastics was found to decrease in the order LDPE, HDPE, PP, SB and ABS. Migration was found to be higher into pure fat and margarine than into mayonnaise. When comparing absorption from different emulsions of fat and water, the ranking for plastics was the same as the above with LDPE having a greater absorption than HDPE, except that ABS and PP had absorptions of the same order whilst it was significantly higher for SB. The type of emulsion was, however, found to have a greater influence on migration of the antioxidant from the polymer than on the fat absorption from the emulsion. The results are discussed in relation to earlier work and also with respect to the classification of foodstuffs.     

Detection of non-milk fat in milk fat by gas chromatography and linear discriminant analysis

Gas chromatography was utilized to determine triacylglycerol profiles in milk and non-milk fat. The values of triacylglycerol were subjected to linear discriminant analysis to detect and quantify non-milk fat in milk fat. Two groups of milk fat were analyzed: A) raw milk fat from the central region of Mexico (n = 216) and B) ultrapasteurized milk fat from 3 industries (n = 36), as well as pork lard (n = 2), bovine tallow (n = 2), fish oil (n = 2), peanut (n = 2), corn (n = 2), olive (n = 2), and soy (n = 2). The samples of raw milk fat were adulterated with non-milk fats in proportions of 0, 5, 10, 15, and 20% to form 5 groups. The first function obtained from the linear discriminant analysis allowed the correct classification of 94.4% of the samples with levels <10% of adulteration. The triacylglycerol values of the ultrapasteurized milk fats were evaluated with the discriminant function, demonstrating that one industry added non-milk fat to its product in 80% of the samples analyzed.     

Influence of high-melting milk fat fraction on quality and fat bloom stability of chocolate

The aim of this paper was to define the optimal concentration of a high-melting milk fat fraction with a suitable precrystallization temperature time regime in order to obtain chocolate which would have satisfactory sensory characteristics and an increased fat bloom stability. The precrystallization was performed in a laboratory crystallizer, that is in a modified Brabender pharinograph, which measures the rheological characteristics of the precrystallized fluid chocolate mass with a milk fat fraction. The experiments were performed according to the factorial plan 3² (two factors on three levels). Hardness as well as solid fat content of chocolate was measured by instrumental methods. The optimal sensory quality of chocolate was achieved by adding 1–3% of the milk fat fraction and under the 25 °C precrystallization temperature. These samples of chocolate showed the highest fat bloom stability.     

脂肪替代品在低脂肉制品中的研究进展

由于低脂肉制品可有效降低脂肪的摄入,且能预防高脂膳食所引起的各种慢性疾病,相关研究领域逐渐成为近年来的研究热点.本文基于国内外低脂肉制品的发展现状,从脂肪替代物、脂肪模拟物和复合型脂肪替代物三个方面综述了各自对低脂肉制品组成成分、组织结构、抗氧化性及感官评价等指标影响的最新研究进展,并就肉制品中脂肪替代物的发展方向进行了展望.