油脂气味的研究进展

气味是油脂一项重要的感观特征指标,也是构成油脂风味的重要因素之一。综述了植物油脂气味的特征成分及其与感官品质之间的关系;气味的形成机理;品种、产地、加工、贮藏方法及条件对油脂气味的形成和组成的影响,目的是为油脂生产和科学研究提供依据。     

脂肪代用品的研究Ⅰ--不同淀粉酶水解马铃薯淀粉制备低DE值麦芽糊精研究

本文采用不同的淀粉酶控制水解马铃薯淀粉制备低DE麦芽糊精作为脂肪模拟品，研究不同淀粉酶作用产物的不同性质，确定了碳水化合物型脂肪模拟品生产用酶为耐高温α-淀粉酶，最佳工艺条件为：酶添加量为0．054g，100ml，温度为88．6℃，时间9．55min，水解产物的DE值为2．20。     

毛细管气相色谱法在山茶籽油掺伪检测中实际应用

该研究选择几种较廉价植物油以不同比例掺入纯山茶籽油,应用毛细管气相色谱法测定模拟掺伪山茶籽油脂肪酸组成与含量,建立由特征脂肪酸与掺入油百分含量近似线性关系标准曲线;并对计算法求出测定值进行误差分析,为实际检测时定量分析脂肪酸组分选取提供依据。     

Cooling causes changes in the distribution of lipoprotein lipase and milk fat globule membrane proteins between the skim milk and cream phase

Lipoprotein lipase (LPL) activity and free fatty acid levels were studied in freshly milked, uncooled milk from individual Danish Holstein or Jersey cows, or after storage for up to 24 h at either a cooling temperature (4°C) or at the milking temperature (31°C). Upon cooling for up to 24 h, LPL activity increased in the cream phase, whereas the activity in the skim milk was steady, as observed for Jersey cows, or increased, as seen for the Holsteins. Storage at 31°C decreased the LPL activity in both the cream phase and the skim milk phase. The increase in free fatty acid levels was found to depend on LPL activity, incubation temperature, substrate availability, and incubation time. Furthermore, the migration of milk proteins between the skim milk phase and the cream phase upon cooling of milk from Jersey cows or from Danish Holstein cows was studied using proteomic methods involving 2-dimensional gel electrophoresis and mass spectrometry. Proteins associated with the milk fat globules were isolated from all milk fractions and analyzed. Major changes in the distributions of proteins between the skim milk phase and the cream phase were observed after cooling at 4°C for 4 h, where a total of 29 proteins between the 2 breeds was found to change their association with the milk fat globule membrane (MFGM) significantly. Among these, the MFGM proteins adipophilin, fatty acid-binding protein, and lactadherin, as well as the non-MFGM proteins β-casein, lactoferrin, and heat shock protein-71, were identified. Adipophilin, lactadherin, and lactoferrin were quantitatively more associated with the MFGM upon cold storage at 4°C, whereas β-casein, fatty acid-binding protein, and heat shock protein-71 were found to be less associated with the MFGM upon cold storage.     

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。     

微生物外源酶对发酵肉制品品质的影响

发酵肉制品的品质特性和微生物外源酶的作用息息相关,蛋白酶、脂肪酶降解蛋白质和脂肪,产生对品质有积极影响的小分子物质,而谷氨酰胺转胺酶、过氧化氢酶、硝酸盐还原酶也对品质的形成起到了协助作用。文中针对微生物源酶与发酵肉制品中蛋白质及脂肪等降解的关系进行了综述。     

多孔淀粉在低脂贡丸中的代脂研究

贡丸是一种广受欢迎的肉制品,但其脂肪含量较高,随着人们对自身健康程度的不断关注,低脂低热食品的需求不断增加。研究了用多孔淀粉替代贡丸中部分脂肪,有效地降低了贡丸的脂肪含量,同时降低产品成本,达到原高脂贡丸所具有的口感和质构。     

利用籼米为基质的脂肪替代品制备低脂火腿肠

用籼米为基质的脂肪替代品替代高脂火腿肠中50%脂肪制得了低脂火腿肠;通过全质构分析和感官评定相结合的方式对低脂火腿肠进行了评价。结果表明,用DE2～3的脂肪替代品替代脂肪制备的低脂火腿肠具有良好的质构和口感,能为广大消费者所接受。DE4的麦芽糊精不适合作为脂肪替代品。     

酶法催化生产1,3-二油酸-2-棕榈酸甘油三酯

1,3-二油酸-2-棕榈酸甘油三酯(OPO)是母乳脂肪中甘油三酯的重要组成成分,可有效改善和保证棕榈酸在婴幼儿体内的吸收和利用。本文对其脂肪酶催化生产进行了简单探索,以三棕榈酸甘油酯(PPP)和油酸(OA)为底物,通过1,3-特异性脂肪酶RMIM催化的酸解反应成功制备了1,3-二油酸-2-棕榈酸甘油三酯。经单因素优化后最佳反应条件为:PPP与油酸摩尔比1:6,加酶量8%,反应温度50℃,反应时间6 h,反应产物中脂肪酸组成为:油酸54.86%,sn-2位棕榈酸含量为87.64%。     

Effects of lipid supplementation on the yield and composition of milk from cows with different β-lactoglobulin phenotypes

Responses to lipid supplementation differ between dairy breeds and genetic lines suggesting nutrition by genotype interactions. β-Lactoglobulin phenotype is associated with changes in yield and composition of milk. The response of cows with different β-lactoglobulin phenotypes to lipid supplementation has not been examined. Furthermore, we examined whether lipid supplementation alters milk protein composition. By using a randomized block design, we fed Holstein cows for 3 wk either a control diet containing 2.8% crude fat (n = 19) or an experimental diet that was supplemented with 4.2% tallow (n = 20). Before randomization, all cows were fed the supplemental tallow diet for at least 2 wk. Dry matter intake, body weight, milk yield, and milk composition were measured in the last week before and during the experimental period. Feeding supplemental tallow increased dry matter intake and yields of milk and milk components, including casein content, without decreasing milk component content or altering milk protein composition. On the low-fat control diet, cows with the β-lactoglobulin allele B had a greater milk and milk component yield than cows with the A allele, whereas no differences by β-lactoglobulin phenotype were observed in cows on the tallow supplement diet. Our results suggest that cows that differ in β-lactoglobulin phenotype respond differently to a low-fat diet and that feeding cows 4.2% of additional tallow increases milk yield without affecting milk component content and milk protein composition.