低酸度川味香肠加工过程中脂肪降解和氧化

在控温控湿条件下接种发酵剂生产低酸度川味香肠,通过测定加工过程中p H、酸价、过氧化值、TBA值和游离脂肪酸组成,并与自然条件下生产的传统川味香肠(对照组)相比较,揭示低酸度川味香肠加工过程中脂肪降解和氧化的规律。实验结果显示,干燥结束时,低酸度川味香肠的p H、过氧化值和TBA值分别为5.50、0.783meq/kg和0.252mg丙二醛/kg,均低于对照组,低酸度川味香肠酸价为2.701mg KOH/g,高于对照组,低酸度川味香肠的单不饱和脂肪酸含量为40.46%,不饱和脂肪酸含量为59.09%,其不饱和脂肪酸含量明显高于对照组(41.99%)。研究结果表明,在整个加工过程中,低酸度川味香肠中的脂肪更容易发生降解,多不饱和脂肪酸更容易产生氧化现象,脂肪氧化在加工过程中持续进行。     

以多糖为基质的脂肪模拟物替代动物脂肪在法兰克福香肠中的应用

将以多糖（魔芋粉、κ-卡拉胶和大麦β-葡聚糖）为基质的脂肪模拟物分别以20%、40%、60%和80%的比例替代猪脂肪用于法兰克福香肠生产中,探讨猪脂肪的不同替代比例对法兰克福香肠品质特性和感官特性的影响。结果表明,随着脂肪模拟物替代比例的增加,香肠的水分含量和碳水化合物含量显著增加（P<0.05）,而总脂质含量、蛋白含量、灰分含量、能量值和脂肪卡路里值显著降低（P<0.05）。而且,随着脂肪替代物替代量的增加,香肠的蒸煮损失率、乳化稳定性显著降低（P<0.05）,亮度值增加,硬度以及咀嚼性降低。另外,低场核磁结果表明替代脂肪能够显著缩短香肠的弛豫时间（P<0.05）,说明其能增强蛋白质网络对水分子的束缚能力。然而,较高的脂肪替代比例（60%和80%）显著降低肉糜在加热终点的储能模量（G′）和损失模量（G′′）（ P<0.05）,而且降低了法兰克福香肠的总体可接受性。上述研究结果表明,以多糖为基质的脂肪模拟物能够在法兰克福香肠中部分替代猪脂肪,且以40%的替代比例为最佳。     

四川香肠加工贮藏过程中表层、中层及内层脂肪的变化规律

根据香肠与空气接触的密切程度将四川香肠分为表、中、内三层,并测定香肠在加工贮藏过程中的水分含量、水分活度、酸价、过氧化值、TBA值和游离脂肪酸组成。实验结果显示,香肠贮藏过程中表层的水分含量和水分活度均低于香肠内部,在贮藏末期,香肠表层和内层的水分含量分别为9.32%和12.51%,水分活度分别为0.62和0.51;在贮藏第120d,香肠表层的酸价、过氧化值和TBA值分别为9.08mg KOH/g、18.33meq/kg和1.52mg丙二醛/kg,均高于中层和内层;贮藏末期,香肠表层的单不饱和脂肪酸含量最高,为50.44%,香肠内层的多不饱和脂肪酸含量最高,为21.23%。研究结果表明,在四川香肠加工贮藏中,其表层的脂肪容易发生水解和氧化,香肠表层脂肪中的多不饱和脂肪酸比中层和内层的多不饱和脂肪酸更容易产生氧化现象。     

德国科学家研发出超低脂肪香肠

<正>德国研究人员研发出一种超低脂肪含量的香肠,这种香肠的脂肪含量从通常的25%～40%降低到2%,是肉类脂肪低含量的极限。这种超低脂肪香肠由德国巴伐利亚州明德海姆肉商与德国著名的夫琅禾费研究所共同研发,研究成果一经推出立即引起了世界各国科学家的兴趣。这种香肠看上去、闻起来跟普通香肠别无二致,吃起来味道和意大利的沙拉密香肠非常相似,但手感较软。发明这一低脂香肠是受客户的启发,由于越来越多的女性顾客经常抱怨香肠的脂肪含量太高,于是决心来一次彻底的"香肠革命"。     

以马铃薯淀粉为基料超声法合成脂肪替代品及其应用研究

在超声波作用下,进行单因素试验,通过改变乙醇浓度、盐酸浓度、底物添加量和反应时间来测定以马铃薯淀粉为基料制备脂肪替代品的影响,并进行试验优化,确定工艺参数。并将其反应产物应用于香肠,根据脂肪含量分析和感官评定打分结果,确定香肠中脂肪替代度为15%。     

干发酵香肠在成熟过程中的脂肪变化及其与芳香成分的关系

概述了干发酵香肠成熟过程中脂肪的变化及其与芳香成分的关系。干发酵香肠在成熟过程中脂肪发生降解,产生游离脂肪酸,脂肪的降解受到温度、pH值、盐分含量及成熟时间等因素的影响。游离脂肪酸本身及其氧化产物是干发酵香肠风味的主要构成成分。     

德国科学家研发出超低脂肪香肠

德国研究人员研发出一种超低脂肪含量的香肠，这种香肠的脂肪含量从通常的25％～40％降低到2％，是肉类脂肪低含量的极限。这种超低脂肪香肠由德国巴伐利亚州明德海姆肉商与德国著名的夫琅禾费研究所共同研发，研究成果一经推出立即引起了世界各国科学家的兴趣。     

燕麦麸脂肪模拟物应用于发酵香肠的工艺优化及其对发酵香肠品质的影响

该研究以燕麦麸提取物冻干粉、魔芋胶、卡拉胶、橄榄油为原料制备成燕麦麸脂肪模拟物(oat bran fat analog,OBFA),在发酵香肠配方中取代部分猪皮下脂肪,生产出一种脂肪含量较低的发酵香肠。采用正交实验对该种发酵香肠的主要加工工艺进行优化,同时对发酵香肠的色泽、质构、理化指标及挥发性风味物质进行测定,探讨燕麦麸脂肪模拟物对发酵香肠品质的影响。实验结果表明,固定发酵温度20℃,发酵相对湿度75%,成熟温度13℃,成熟相对湿度60%,成熟周期4 d以及烘干温度55℃的前提下,OBFA发酵香肠的脂肪模拟物最佳添加量为65%,最佳发酵时间为12 h,最佳烘干时间22 h。此工艺条件下得到的OBFA发酵香肠的感官评分为87.5分,与传统发酵香肠相比亮度增加,硬度增大,但整体可接受性与传统发酵香肠差异不显著;OBFA发酵香肠的pH值为5.58,能量值为3.94 k J/100g,脂肪含量为31.27%,与传统发酵香肠相比,能量值和脂肪含量分别降低了32.26%、20.13%;蛋白质含量为34.04%,提高了38.26%。综上表明,OBFA可以作为脂肪模拟物应用于发酵香肠中。     

脂肪添加量对熏煮香肠质构的影响

研究了不同脂肪添加量(0%、10%、20%、30%、40%、50%)对熏煮香肠质构品质的影响。结果表明:随着脂肪添加量的增加,熏煮香肠的感官硬度逐渐下降,感官弹性先升高后下降,感官质构总分逐渐下降,但添加量20%、30%、40%的感官质构总分差异不显著(P>0.05);熏煮香肠的机械测定硬度、胶着性、回复性、内聚性、咀嚼性随着脂肪添加量的增加逐渐减小(P<0.05),而脂肪添加量对熏煮香肠的黏着性无显著影响(P>0.05)。硬度与脂肪含量呈现较好的线性关系:硬度值=-1 075.9×脂肪添加量+7 875.5(R2=0.932 8);依据质构机械测定值建立的Fisher线性判别方程能准确判别熏煮香肠的脂肪添加等级。     

德国科学家研发出超低脂肪香肠

德国研究人员最近研发出一种超低脂肪含量的香肠，这种香肠的脂肪含量从通常的25％至40％降低到2％，已经是肉类脂肪低含量的极限。 据德国之声电台网站报道，这种超低脂肪香肠由德国巴伐利亚州明德海姆肉商波伊恩特尔与德国著名的夫琅禾费研究所共同研发，研究成果一经推出立即引起了世界各国科学家的兴趣。     

自动脂肪测定仪在大豆脂肪测定中的应用

取不同品种的大豆样品,经粉碎后分别用自动脂肪测定仪(FAFA)及索氏脂肪抽提器对照测定其脂肪含量。结果表明,大豆样品经Perten3100实验磨粉碎,用FAFA进行脂肪含量测定,浸泡时间30min,抽提时间60min,取得了与国标方法相同的结果,而且缩短了工作时间,提高了工作效率。     

Effect of mechanical treatments applied to milk fat on fat retention and lipolysis in minicurds

The aim of this work was to identify a treatment on milk fat, applicable to pretreat cheese milk, which could enhance lipolysis. Three factors were studied in milk fat mixtures: physical treatment (pumping and mechanical agitation), temperature (5, 15, and 45°C) and fat content (5%, 15%, and 30%). Damage to fat globule was estimated by assessing free fat and by phase contrast microscopy. Moderate damage was achieved in a mixture of 30% of fat, treated with mechanical agitation at 2800 rpm/2 min at 5°C. Applying this procedure to prepare minicurds did not modify values of fat content, moisture and lipolysis.     

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.     

Sensory perception of fat in common foods using two scaling methods

Seventy-three subjects evaluated fat content and preference for six different foods using a ranking task and a line scale, and the results from the two methods were compared. The foods included milk, pudding, mashed potatoes, and chicken spread (0–30% added fat), scrambled eggs (0–50% added fat) and a savory snack (low-high in added fat). Samples within a series were formulated to minimize appearance and flavor differences. The perception of fat in these foods appeared to be system-specific. Subjects effectively judged increasing fat content in the milk, pudding, potato, and snack samples, but could not reliably judge fat content in the chicken spreads and scrambled eggs. The hedonic ratings were unrelated to the ability to perceive fat in these foods. Both scaling techniques were effective in scaling these perceptions.     

Cholesterol content and lipid composition of low fat dairy products

The lipid composition of different products obtained from the same raw milk was investigated. The cholesterol content of skim milk (0.05% total fat) and butter milk (0.57% total fat) lipids was 4.20% and 1.31%, respectively, while raw milk lipids and butter fat contained 0.34% or 0.30%, respectively. As the cholesterol content of these low fat milk products increases with decreasing fat content, equations were derived to estimate the fat-related cholesterol content from the value analysed in butter fat. In contrast to the fat-related cholesterol content, the product-related content is still relatively small in skim and butter milk. Their fat-related cholesterol content was found to be influenced by drying. The high content of phospholipids in skim and butter milk led to considerable changes in the fatty acid composition and affected the detection of foreign fat by butyric acid as well as by triglycerides. Skim and butter milk lipids contained only 2.41% or 2.33% butyric acid, respectively, instead of 3.36% found in raw milk lipids. Further, the overlap of phospholipids as well as cholesterol with the gas chromatographic triglyceride pattern resulted in calculated foreign fat contents of more than 20%.     

脂肪替代品模拟脂肪的机理

适当的使用脂肪替代品能安全有效地降低食品中的脂肪含量,并且脂肪替代品在减少总膳食能量和脂肪摄入量方面扮演着越来越重要的角色。脂肪替代品分为4类:碳水化合物基质、蛋白质基质、脂肪基质和复合型脂肪替代品。对4类脂肪替代品模拟脂肪的机理进行了简单的综述,以期为脂肪替代品的研究、开发与应用提供参考。     

食品中脂肪含量的测量不确定度分析与评定

采用索氏抽提法测定油炸方便面脂肪含量,通过建立数学模型确定油炸方便面中脂肪含量,分析测量过程中测量不确定度的来源,对测量测量不确定度来源进行A类评定和B类评定,确定了合成测量不确定度和扩展测量不确定度,最终得出油炸方便面中的脂肪测量不确定度,确定了脂肪测量不确定度的主要来源是自动脂肪测定仪引入的测量不确定度分量。     

Comparison of gas chromatographic methods for analysis of butyric acid in milk fat and fats containing milk fat

 The analysis of butyric acid (C4) is of importance for the determination of the proportion of milk fat in mixed fats. Three gas chromatographic methods were compared with regard to their precision for the measurement of C4, i.e. analysis of butyric acid methyl ester after trans-esterification of fat by sodium methylate (method A) or trimethyl sulphonium hydroxide (method B), as well as analysis of free butyric acid (method C), using an internal standard with each method. The examination of 30 milk fats which varied greatly in terms of their C4 content, using methods A, B and C, resulted in mean values of C4 of 3.42 g/100 g fat, 3.71 g/100 g fat and 3.06 g/100 g fat, respectively. The value determined using method B seemed too high, and this may have been due to the presence of co-eluting artefacts, whereas the value determined using method C was clearly too low, and can probably be attributed to losses during sample preparation. The standard deviation (SD) of 0.015 obtained from repeated analyses using method A was quite good. Results obtained using methods B and C had SDs of 0.029 and 0.074, respectively. Different levels of free fatty acids did not affect the results obtained using method A. When method A was checked by analysis of the reference fat, CRM 164, the C4 level determined was found to deviate from the certified C4 content of 3.49 (± 0.06) g/100 g fat by only 0.05 g C4/fat 100 g. Thus method A proved the most suitable for the determination of the proportion of milk fat in mixed fats by analysis of butyric acid. Received: 1 October 1997     

Comparison of gas chromatographic methods for analysis of butyric acid in milk fat and fats containing milk fat

 The analysis of butyric acid (C4) is of importance for the determination of the proportion of milk fat in mixed fats. Three gas chromatographic methods were compared with regard to their precision for the measurement of C4, i.e. analysis of butyric acid methyl ester after trans-esterification of fat by sodium methylate (method A) or trimethyl sulphonium hydroxide (method B), as well as analysis of free butyric acid (method C), using an internal standard with each method. The examination of 30 milk fats which varied greatly in terms of their C4 content, using methods A, B and C, resulted in mean values of C4 of 3.42 g/100 g fat, 3.71 g/100 g fat and 3.06 g/100 g fat, respectively. The value determined using method B seemed too high, and this may have been due to the presence of co-eluting artefacts, whereas the value determined using method C was clearly too low, and can probably be attributed to losses during sample preparation. The standard deviation (SD) of 0.015 obtained from repeated analyses using method A was quite good. Results obtained using methods B and C had SDs of 0.029 and 0.074, respectively. Different levels of free fatty acids did not affect the results obtained using method A. When method A was checked by analysis of the reference fat, CRM 164, the C4 level determined was found to deviate from the certified C4 content of 3.49 (± 0.06) g/100 g fat by only 0.05 g C4/fat 100 g. Thus method A proved the most suitable for the determination of the proportion of milk fat in mixed fats by analysis of butyric acid. Received: 1 October 1997     

Puff pastry and trends in fat reduction: an update

Puff pastry is a popular nonleavened pastry product with unique textural properties. Puff pastry is processed from laminated dough, comprising alternating and discrete layers of dough and fat. Puff pastry quality can vary substantially depending on the raw material quality and production processes. The high fat content of commercial puff pastry usually containing significant amounts of saturated and trans fats, which are known to be associated with potential health risks, has led to increased demand for lower fat baked products. This review discusses the puff pastry production process and factors affecting puff pastry quality together with strategies to reduce total fat content and improving the fat composition in puff pastries.