超临界流体萃取柚子皮香精油的工艺研究

采用超临界CO2萃取技术提取柚子皮香精油,研究了萃取温度、萃取压力、CO2流量等因素对柚子皮精油萃取率的影响,并进行了最佳工艺优化。结果表明,超临界CO2流体萃取柚子皮香精油的工艺是可行的,最佳工艺条件：原料粒度60目、流量25L/h、萃取时间80min、温度50℃、压力25MPa,其萃取率为5.12%。     

紫花苜蓿芽及其产品中氨基酸含量的测定与营养分析

通过氨基酸分析仪分别测定了紫花苜蓿芽及其产品中氨基酸的含量,分别计算了必需氨基酸含量、必需氨基酸/氨基酸总量(E/T)、必需氨基酸/非必需氨基酸(E/N)、氨基酸评分(AAS)和必需氨基酸指数(EAAI),综合评价苜蓿芽及其产品的食用价值。测定结果表明,紫花苜蓿芽及其产品中含有18种氨基酸,包含9种必需氨基酸。紫花苜蓿芽和苜蓿芽产品中氨基酸总含量、必需氨基酸、E/T、E/N分别为25.27%和18.75%、9.34%和7.757%、36.96%和41.37%、58.63%和70.56%。紫花苜蓿芽及其产品必需氨基酸中苏氨酸的含量都最高,色氨酸是紫花苜蓿芽及其产品共同的第一限制性氨基酸,氨基酸评分分别是56.74%和98.58%。在紫花苜蓿芽中含硫氨基酸(蛋氨酸 胱氨酸)是第二限制性氨基酸,而在其产品中不是。必需氨基酸指数计算结果表明,苜蓿芽及其产品蛋白均属优质蛋白。综合评价认为苜蓿芽及其产品中蛋白质具有很高的食用价值,该苜蓿产品加工工艺提高了苜蓿蛋白的食用价值。     

肉桂精油抑茵活性研究

利用滤纸片液相和气相扩散法进行体外抑菌试验,测定肉桂精油对6种供试菌的抑菌圈直径和最小抑菌浓度,以及加热处理和pH值对精油抑菌效果的影响.结果表明:肉桂精油对各供试茵的抑茵圈直径在19.6～43.5mm,对细菌、霉菌和酵母均有很强的抑制作用,对霉菌的抑菌作用高于酵母菌和细菌;气相也具有较强的抑茵作用;120℃加热处理20min对内桂精油的抑菌效果无明显影响;在pH值偏酸或偏碱时内桂精油的抑菌效果增强.     

植物精油防控果蔬采后病害的应用探究

我国是世界果蔬产销大国之一。果品蔬菜在满足人们需求的同时,也面临着严峻的贮藏问题。作为一种天然植物源保鲜剂,精油类果蔬防腐保鲜剂的研发与应用广受关注。植物精油多提取于香辛料及中草药植物的花、叶、茎、根或果实,具有显著的抑菌效果,因而被广泛用于果蔬采后病害的防控。目前,精油及其抑菌成分在国内果蔬采后贮藏的应用研究已取得了一定的成效,但较之国外的研究还相对落后。该文依据国外内最新的研究动态,通过综述精油的植物源种类、应用现状趋势的最新研究进展,以期为果蔬采后病原微生物的抑杀和生理性病害的防控提供理论基础和实践参考。     

超临界CO2提取八角茴香精油及其对肉类抑菌效果稳定性的研究

文章采用超临界CO2提取八角茴香精油,研究了精油浓度、温度、光照时间及热处理等因素对八角茴香精油抑菌效果和肉类感官特征的影响。结果表明,超临界CO2提取八角茴香精油的得率为4.5%;八角茴香精油的最低抑菌浓度为7.0%,且能够保持肉糜优良的感官特征;加入精油的新鲜肉糜的保存期随着温度的改变而改变,在4,25,35℃条件下分别可以保存4天,6 h和4 h;当温度为37℃时,光照显著破坏挥发油的稳定性,254 nm紫外光照射40 min以上或365 nm紫外光照射30 min以上将使精油失去活性;长时间热处理导致精油的抑菌活性下降。     

Oregano: chemical analysis and evaluation of its antimalarial, antioxidant, and cytotoxic activities

Abstract: GC‐FID and GC‐MS analysis of essential oil from oregano leaves (Origanum compactum) resulted in the identification of 46 compounds, representing more than 98% of the total composition. Carvacrol was the predominant compound (36.46%), followed by thymol (29.74%) and p‐cymene (24.31%). Serial extractions with petroleum ether, ethyl acetate, ethanol, and water were performed on aerials parts of Origanum compactum. In these extracts, different chemical families were characterized: polyphenols (gallic acid equivalent 21.2 to 858.3 g/kg), tannins (catechin equivalent 12.4 to 510.3 g/kg), anthocyanins (cyanidin equivalent 0.38 to 5.63 mg/kg), and flavonoids (quercetin equivalent 14.5 to 54.7 g/kg). The samples (essential oil and extracts) were subjected to a screening for antioxidant (DPPH and ABTS assays) and antimalarial activities and against human breast cancer cells. The essential oil showed a higher antioxidant activity with an IC₅₀= 2 ± 0.1 mg/L. Among the extracts, the aqueous extract had the highest antioxidant activity with an IC₅₀= 4.8 ± 0.2 mg/L (DPPH assay). Concerning antimalarial activity, Origanum compactum essential oil and ethyl acetate extract showed the best results with an IC₅₀ of 34 and 33 mg/mL, respectively. In addition, ethyl acetate extract (30 mg/L) and ethanol extract (56 mg/L) showed activity against human breast cancer cells (MCF7). The oregano essential oil was considered to be nontoxic.     

A Blend of Essential Plant Oils Used as an Additive to Alter Silage Fermentation or Used as a Feed Additive for Lactating Dairy Cows

A blend of essential plant oils was evaluated for its effects on silage fermentation and animal performance. In the first experiment, the blend of essential oils was mixed with freshly chopped whole-plant corn to achieve a concentration of 0, 40, or 80 mg of active product per kilogram of fresh forage weight. Whole-plant corn was also mixed with a buffered propionic acid-based product at 0.2% of fresh forage weight. The blend of essential oils did not affect the populations of yeasts, molds, lactic acid bacteria, or enterobacteria; the fermentation end products; or the aerobic stability of the corn silage. Addition of the buffered propionic acid additive moderately reduced the production of acids during fermentation and resulted in a small reduction in the numbers of yeasts after ensiling, but did not affect aerobic stability. In a second experiment, 30 Holstein cows (4 primiparous and 26 multiparous) averaging 118 ± 70 d in milk and producing 38 ± 16 kg of milk/d were fed a total mixed ration, once daily, that consisted of (on a DM basis) 25% corn silage, 15% alfalfa silage, 10% alfalfa hay, and 50% concentrate. One-half of the cows were fed a blend of essential oils that was mixed directly into their total mixed ration to provide 1.2 g/cow per d for 9 wk. Cows fed the essential oils ate 1.9 kg more dry matter/d and produced 2.7 kg more 3.5% fat-corrected milk/d than did cows fed the control diet. The percentages of milk fat and protein, the somatic cell count numbers, and the concentrations of milk urea nitrogen were unaffected by treatment. Feed efficiency, change in body weight, and change in body condition scoring were also similar between treatments. After 12 h of incubation, the addition of a moderate dose and a high dose of essential oils to in vitro ruminal fermentations had no effect on the concentration of total VFA compared with the control treatment. However, they decreased the molar proportions of acetic, butyric, and valeric acids and increased the proportion of propionic acid. The blend of essential oils evaluated in this study altered in vitro ruminal fermentation and improved animal performance when fed directly to cows, but it did not affect the fermentation or aerobic stability of corn silage.     

微波法和水蒸气蒸馏法提取丁香精油的研究

以丁香为原料,分别采用微波法和水蒸气蒸馏法提取精油,探讨微波萃取对丁香精油提取率和精油品质的影响。以丁香精油提取率为指标,通过正交试验优化微波提取条件,采用气相色谱-质谱(GC-MS)法鉴定其化学成分,并与水蒸气蒸馏法提取的精油进行比较。结果表明,微波萃取丁香精油的最佳工艺参数为微波功率300 W、料液比1∶4(m∶V)、微波时间25s、提取次数4,该条件下精油的提取率可达到20.65%,远远高于水蒸气蒸馏法的11.33%;从该精油中鉴定出19种成分,其中3种丁香精油有效成分的得率分别为丁香酚13.2%、石竹烯4.4%、乙酰基丁香酚2.2%,石竹烯和乙酰基丁香酚得率分别是水蒸气蒸馏精油的2.8倍和2倍。微波萃取是丁香精油较有效的提取方式。     

用淀粉酶提高雪糕中淀粉用量的研究

采用淀粉酶对雪糕中的淀粉进行水解,改变淀粉的分子结构,可以防止淀粉老化返生,消除淀粉味感;增加淀粉的用量,降低白砂糖、奶粉、奶油的用量,从而降低产品的生产成本,同时也可使产品口感细腻、柔软,质量得到改善,膨胀率在90-100%。     

生姜精油的研究新进展

生姜是我国一种历史悠久的药食兼用的香辛调味料 ,生姜精油是衡量生姜加工特性的重要指标 ,也是生姜加工产品质量的保证。文章主要综述了生姜精油的理化性质、生姜精油的组分、生姜精油的功能作用、生姜精油提取方法及产品开发应用方面的研究进展 ,并提出了生姜精油研究开发的新思路