长柄扁桃仁及其水酶法油脂的品质研究

本文分析了新油料资源长柄扁桃仁的主要成分,同时采用水酶法提油技术提取长柄扁桃仁油脂,并对该油脂特性进行了研究。结果表明,长柄扁桃仁中粗脂肪含量44.10%,粗蛋白含量24.70%。仁中氨基酸种类齐全,属于完全蛋白,其中鲜味氨基酸含量最高,达72.50 mg/g,占味觉氨基酸含量的29.95%。鲜味氨基酸谷氨酸(Glu)和门冬氨酸(Asp)、甜味氨基酸甘氨酸(Gly)、脯氨酸(Pro)和丙氨酸(Ala)、芳香氨基酸苯丙氨酸(Phe)含量相对较高,占总氨基酸含量的55.50％,为长柄扁桃仁增添了良好风味。在水酶法提油工艺参数料液比1:4(g/mL),酶解温度60℃,酶添加量2%,酶解pH8.5时,长柄扁桃仁总出油率为39.51%,萃取率达89.59%,其中不饱和脂肪酸含量达97.4%,油酸和亚油酸含量分别高达66.6%和29.6%,油中活性物质生育酚含量为989.3 mg/kg,这些数据的分析为长柄扁桃籽资源多方位的开发利用提供参考。     

典型木本油料油脂的特性分析

本文研究了油茶籽油、核桃油、橄榄油、杏仁油、文冠果油、长柄扁桃油6种木本油料种仁油脂的脂肪酸组成、微量营养成分含量以及荧光特性。研究表明,油茶籽油、橄榄油、杏仁油、长柄扁桃油的脂肪酸以油酸为主(杏仁油65.61%~油茶籽油80.58%),核桃油的脂肪酸以亚油酸(64.19%)为主,文冠果油的脂肪酸以油酸和亚油酸为主;6种油脂中,橄榄油微量营养组分中总酚含量最高,为725.64 mg没食子酸/kg,长柄扁桃油中生育酚和植物甾醇含量均最高,分别为61.06 mg/100 g和314.53 mg/100 g;6种毛油中,长柄扁桃油的氧化稳定性最佳(OSI值13.87 h);荧光扫描显示6种木本油料油脂具有不同的荧光光谱特性,一定程度上可以作为木本油料鉴伪的手段。     

提取方法对长柄扁桃油稳定性及货架期的影响

采用冷榨法(CP)和超临界CO_2萃取法(SFE)提取长柄扁桃油,分析其理化指标和营养成分;通过烘箱储存试验,以过氧化值(POV)为参考指标,研究了长柄扁桃油在65、50、40、30、20℃下的氧化稳定性;采用油脂氧化酸败仪(Rancimat)法比较了长柄扁桃油与其他油的氧化稳定性。结果表明,超临界CO_2萃取法提取的长柄扁桃油(SFEO)营养成分含量高于冷榨法提取的长柄扁桃油(CPO);温度越高,氧化速度越快;长柄扁桃油的氧化稳定性要高于其他油。CPO和SFEO氧化均遵循一级化学反应,通过外推法得出CPO在20、25、30℃的货架期分别为194、127、84 d;SFFO在20、25、30℃的货架期分别为180、126、90 d,均具有较好的稳定性。     

长柄扁桃油脂肪酸成分分析

长柄扁桃是一种新型的沙生木本油料植物。采用GC-MS法对长柄扁桃油的脂肪酸成分进行分析。结果表明,长柄扁桃种仁中油含量在55%以上,由棕榈酸、棕榈油酸、油酸、亚油酸、亚麻酸、花生烯酸和芥酸7种脂肪酸组成,其中不饱和脂肪酸高达98.1%,单不饱和脂肪酸与多不饱和脂肪酸的比例与橄榄油比例相似,芥酸含量仅为0.8%。表明长柄扁桃油是一种品质优良的食用油,具有广阔的开发前景。     

响应面法优化长柄扁桃肽的酶解制备工艺

为高值化开发长柄扁桃种仁蛋白,以长柄扁桃种仁为原料,脱脂后提取水溶性蛋白,采用蛋白酶对其酶解制备长柄扁桃肽。通过比较5种蛋白酶对长柄扁桃水溶性蛋白水解度及酶解产物抗氧化活性的影响,优选合适的酶解用酶,在此基础上,采用单因素实验和响应面实验优化了长柄扁桃多肽的制备工艺。结果表明：采用碱性蛋白酶酶解可以得到更高的长柄扁桃蛋白水解度(16.03%)和酶解产物DPPH自由基清除率(59.49%),更适于长柄扁桃蛋白的酶解;长柄扁桃蛋白的最优酶解工艺条件为酶解温度57℃、酶解时间4 h、碱性蛋白酶用量1 192 U/g、pH 8.4,在此条件下长柄扁桃蛋白水解度为18.12%。酶解长柄扁桃蛋白制备多肽可提高长柄扁桃种仁的附加值,同时可为功能性肽产品提供优质原料。     

不同产地野生长柄扁桃仁氨基酸组成及营养价值评价

采集主产区陕西省和内蒙古自治区11 个地区的长柄扁桃仁为实验材料,采用氨基酸自动分析仪测定其氨基酸组成,并进行了营养价值评价。结果表明,不同产地长柄扁桃仁总氨基酸含量在21.74～32.35 mg/g之间,平均为26.78 mg/g;必需氨基酸占总氨基酸比例范围在24.86%～28.22%之间,第一限制氨基酸为蛋氨酸,氨基酸比值系数分平均值为69.13;以氨基酸总量、必需氨基酸含量等指标,将11 个产地长柄扁桃仁氨基酸聚类分为4 类,其中呼和浩特市小井沟生态园长柄扁桃仁蛋白含量最高,品质最好;长柄扁桃仁中味觉氨基酸和药用氨基酸含量丰富,开发利用潜质较大。     

长柄扁桃加工产品中苦杏仁苷及其降解产物野黑樱苷质谱定性和定量分析

建立了长柄扁桃加工产品中苦杏仁苷及其降解产物野黑樱苷的定性和定量分析方法。长柄扁桃饼(粕)、长柄扁桃油样品经甲醇超声萃取后,采用HPLC-Q-TOF,经C18柱(100 mm×2. 1mm,2. 7μm)分离进行定性分析;采用UPLC-TSQ,在C18柱(100 mm×2. 1 mm,1. 7μm),电喷雾ESI源,正离子模式条件下进行定量分析。结果表明:建立的定性方法,经相对保留时间、精确相对分子质量和二级碎片比对,鉴定出苦杏仁苷及其降解产物野黑樱苷;建立的定量方法对于饼粕、油脂样品中苦杏仁苷和野黑樱苷线性范围分别为50～1 000 ng/m L,50～800 ng/m L;对于饼粕样品苦杏仁苷、野黑樱苷平均加标回收率分别为99. 2%～100. 5%和102. 0%～105. 8%,精密度分别为0. 1%～3. 3%和1. 6%～3. 6%,检出限分别为2. 5、5 mg/kg;对于油脂样品苦杏仁苷、野黑樱苷平均加标回收率分别为99. 1%～108. 3%和102. 9%～108. 9%,精密度分别为1. 5%～2. 2%和1. 0%～3. 5%,检出限分别为0. 06、0. 12 mg/kg。该定量方法快速简便,为保障长柄扁桃加工产品的安全提供了技术支撑。     

响应面法优化超声-微波协同提取长柄扁桃油工艺

研究超声微波辅助提取长柄扁桃油的工艺。利用响应面法对长柄扁桃油的提取工艺条件进行优化。在单因素试验的基础上,根据中心组合设计原理采用3因素3水平的响应面分析法,依据回归分析确定最优提取工艺条件。选取提取温度、提取时间和液料比作为影响因子进行优化,研究结果表明,长柄扁桃油的最佳工艺条件为:提取温度50.56℃,提取时间19.73 min,提取料液比13.77 mL/g,在此条件下所能达到油的最大得率为53.11%。     

沙生植物长柄扁桃种子油营养成分分析

探讨以长柄扁桃为原料开发新型食用植物油的可能性。采用国家标准对内蒙古产长柄扁桃仁压榨油进行了常见理化指标、营养成分、卫生指标分析及急性毒性试验研究。长柄扁桃种子油理化性能良好,是一种营养丰富的植物油源;总砷、铅、及黄曲霉毒素B_1含量符合食用植物油卫生标准;急性毒性实验结果初步判定其安全性。长柄扁桃油可开发为新型高品质食用油。     

响应面法优化长柄扁桃中苦杏仁苷的提取工艺

为了综合利用长柄扁桃,提高利用价值,本实验通过响应面实验设计,以苦杏仁苷提取率为响应值,对长柄扁桃中苦杏仁苷的提取参数进行优化。优化后的最佳工艺条件为:乙醇浓度90%,料液比1∶6g/mL,提取时间55min,苦杏仁苷的提取率为提取率为86.91%。     

反式脂肪酸危害与控制

通过对食品中反式脂肪酸含量强制标示,向广大消费者指出反式脂肪酸对人体健康危害;同时对油脂加工业而言,这也意味着一场旨在减少食品中反式脂肪酸变革开始。     

花生四烯酸分离纯化方法研究进展

花生四烯酸是人体必需不饱和脂肪酸,具有极高保健价值。该文介绍并比较花生四烯酸分离纯化方法,主要包括低温溶剂结晶法,脲包法,银离子络合法,超临界萃取法,高效液相色谱法等方法。     

Milk fatty acids as possible biomarkers to early diagnose elevated concentrations of blood plasma nonesterified fatty acids in dairy cows

Most cows encounter a state of negative energy balance during the periparturient period, which may lead to metabolic disorders and impaired fertility. The aim of this study was to assess the potential of milk fatty acids as diagnostic tools of detrimental levels of blood plasma nonesterified fatty acids (NEFA), defined as NEFA concentrations beyond 0.6 mmol/L, in a data set of 92 early lactating cows fed a glucogenic or lipogenic diet and subjected to 0-, 30-, or 60-d dry period before parturition. Milk was collected in wk 2, 3, 4, and 8 (n = 368) and blood was sampled weekly from wk 2 to 8 after parturition. Milk was analyzed for milk fatty acids and blood plasma for NEFA. Data were classified as “at risk of detrimental blood plasma NEFA” (NEFA ≥0.6 mmol/L) and “not at risk of detrimental blood plasma NEFA” (NEFA <0.6 mmol/L). Concentrations of 45 milk fatty acids and milk fat C18:1 cis-9-to-C15:0 ratio were subjected to a discriminant analysis. Milk fat C18:1 cis-9 revealed the most discriminating variable to identify detrimental blood plasma NEFA. A false positive rate of 10% allowed us to diagnose 46% of the detrimental blood plasma NEFA cases based on a milk fat C18:1 cis-9 concentration of at least 230 g/kg of milk fatty acids. Additionally, it was assessed whether the milk fat C18:1 cis-9 concentrations of wk 2 could be used as an early warning for detrimental blood plasma NEFA risk during the first 8 wk in lactation. Cows with at least 240 g/kg of C18:1 cis-9 in milk fat had about 50% chance to encounter blood plasma NEFA values of 0.6 mmol/L or more during the first 8 wk of lactation, with a false positive rate of 11.4%. Profit simulations were based on costs for cows suffering from detrimental blood plasma NEFA, and costs for preventive treatment based on daily dosing of propylene glycol for 3 wk. Given the relatively low incidence rate (8% of all observations), continuous monitoring of milk fatty acids during the first 8 wk of lactation to diagnose detrimental blood plasma NEFA does not seem cost effective. On the contrary, milk fat C18:1 cis-9 of the second lactation week could be an early warning of cows at risk of detrimental blood NEFA. In this case, selective treatment may be cost effective.     

膳食中的脂肪酸平衡

本文综述了膳食中三类脂肪酸（饱和脂肪酸、单不饱和脂肪酸及多不饱和脂肪酸）的营养学功能，并就有关膳食脂肪酸的平衡及n-6与n-3的合适比例作了总结。     

东北不同杂豆油脂含量及脂肪酸组成分析

为开发与利用东北杂豆资源,本文以东北特有杂豆为原料,采用气质分析方法对杂豆脂肪含量及脂肪酸组成进行初步分析。结果表明：杂豆中含有丰富的不饱和脂肪酸,且在测定所有杂豆中均是高活性的n:3、n:2类不饱和脂肪酸含量高,而活性相对的n:1类不饱和脂肪酸含量低。芸豆类杂豆的脂肪酸中不饱和脂肪酸含量均大于80%;且高活性的n:3类不饱和脂肪酸含量较多,紫花芸豆的n:3类不饱和脂肪酸含量达到了48.99%,具有进一步开发应用的价值。本研究为东北杂豆的综合利用提供了理论参考与依据     

α-亚麻酸研究进展

α-亚麻酸属于n-3系列多不饱和脂肪酸,分子结构为△9,12,15-18:3,主要来源于陆地植物, 如杜仲、藿香、亚麻、紫苏等。在体内代谢过程中,它主要作为EPA和DHA前体物质,并具有降低胆固醇、血脂,预防心血管疾病、保护视力和抑制过敏反应等功能。该文主要介绍α-亚麻酸的来源、分离提取方法进展及生理功能,并对α-亚麻酸发展前景进行展望。     

近红外光谱法快速检测婴儿配方奶粉中的脂肪酸含量

采用傅里叶近红外光谱结合偏最小二乘法(PLS)法建立了测定婴儿配方奶粉中的总脂肪酸、饱和脂肪酸和不饱和脂肪酸含量的近红外数学模型,并通过交互验证和外部检验两种方式考察了近红外数学模型的可靠性。通过选择不同的波长范围,采用平滑、矢量归一化、一阶求导、二阶求导和散射校正对近红外光谱进行处理,总脂肪酸、饱和脂肪酸和不饱和脂肪酸的校正模型相关系数(R2)分别为0.9337、0.9374、0.9020,RPD分别为3.63、3.65、2.90。结果表明近红外数学模型具有良好的预测性能。采用建立的模型对验证集中的20个婴儿配方奶粉样品进行预测,总脂肪酸含量、饱和脂肪酸和不饱和脂肪酸的预测值与化学测定值之间经配对t检验分析,与常规化学方法得到的检验结果无显著差异。     

坚果中脂肪含量及脂肪酸组成分析

目的分析16种市售坚果中脂肪含量及脂肪酸组成,比较不同品种坚果间脂肪含量、饱和脂肪酸和不饱和脂肪酸组成的差异。方法采用气相色谱分析法测定坚果中37种脂肪酸的含量,用最小显著性差异法(least-significant difference,LSD)法进行多重比较。结果坚果的平均脂肪含量为(55.6±0.86)g/100 g,变化范围为40.2~71.3 g/100 g,碧根果脂肪含量显著高于其他品种坚果脂肪含量(P0.05);坚果中的不饱和脂肪酸含量为72.77~95.47 g/100 g脂肪,平均值为(86.68±0.12)g/100 g脂肪,显著高于饱和脂肪酸4.53~22.19 g/100 g脂肪,平均值为(11.31±0.16)g/100 g脂肪(P0.05),东北榛子中单不饱和脂肪酸总含量最高,为84.34 g/100 g脂肪,而纸皮核桃中的多不饱和脂肪酸总含量最高,为74.17 g/100 g;坚果中不含短链脂肪酸和中链脂肪酸。结论坚果中不饱和脂肪酸含量较多,富含ω-6和ω-3脂肪酸,营养价值较高。     

Effect of ruminal pulse dose of polyunsaturated fatty acids on ruminal microbial populations and duodenal flow and milk profiles of fatty acids

The objective of this study was to examine the effect of ruminal pulse dose of free linoleic acid (LA) and free docosahexaenoic acid (DHA) on microbial populations in the rumen, duodenal fatty acid (FA) flow, milk composition, and milk FA profiles of Chinese Holstein dairy cows. Four rumen- and duodenal-fistulated Chinese Holstein cows in mid lactation (138.5 ± 10 d in milk) were randomly assigned to 3 treatment groups and 1 control group in a 4 × 4 Latin square design over 4 periods (3 wk per period). Diets contained either no LA or 2.7% LA and either no DHA or 0.5% DHA in a 2 × 2 factorial arrangement of treatments. Ruminal pulse dose with DHA increased counts of Megasphaera elsdenii, decreased Fibrobacter succinogenes, but did not affect Butyrivibrio fibrisolvens or Ruminococcus flavefaciens. The pulse dose of LA at 2.7% dry matter had no effect on the population sizes of the 3 major cellulolytic bacterial species or M. elsdenii, and no interaction was observed between LA and DHA. The pulse dose of LA or DHA, either alone or in combination, increased the duodenal flow of vaccenic acid (VA). The milk VA and cis-9,trans-11 conjugated linoleic acid (CLA) contents also increased in response to the fatty acid pulse dose, and the pulse dose of both LA and DHA together had the most profound stimulatory effect. This study indicated that ruminal pulse dose of LA or DHA could be used to increase duodenal flow of VA and the milk contents of potentially health-promoting FA, such as VA and cis-9,trans-11 CLA. These results might be useful in formulating dietary interventions to improve milk cis-9,trans-11 CLA contents.     

Unrestricted feed intake during the dry period impairs the postpartum oxidation and synthesis of fatty acids in the liver of dairy cows

The purpose of this study was to determine the activities of key hepatic enzymes of fatty acid synthesis and oxidation in cows that had excessive body fat at parturition. Dairy cows were allocated to either an experimental group or a control group. All cows were offered a total mixed ration with an energy content of 6.6 MJ of net energy for lactation per kilogram of dry matter and consisting of corn silage, beet pulp, rapeseed meal, and soybean meal. Control cows were restricted to 6.8 kg/dry matter of the mixed ration in the dry period. Experimental cows had unrestricted access to the mixed ration during the dry period to increase body fat and induce fatty liver postpartum. Blood and liver samples were collected 1 wk before and 1, 2, and 4 wk after parturition. Before parturition, neither the serum nonesterifled fatty acids nor the hepatic triacylglycerol concentrations differed between experimental and control cows. After parturition, the values for these variables were greater in experimental cows than in control cows. Plasma 3-hydroxybutyrate increased sharply after parturition in the experimental group. In liver, the activity of acetyl-CoA carboxylase was already significantly lower in the experimental group before parturition. After parturition, the activities of acetyl-CoA carboxylase and fatty acid synthase dropped in the experimental group. The activity of 3-hydroxy-acyl-CoA dehydrogenase in liver was less in experimental cows following parturition. Hepatic citrate synthase activity increased only in the control group after parturition. Unrestricted feed intake before parturition reduces de novo fatty acid synthesis as well as fatty acid oxidation after parturition. The reduction in fatty acid oxidation following parturition may contribute to postpartum accumulation of triacylglycerol in the livers of cows with unrestricted access to feed during the dry period.