不同大蒜精油成分及生物活性对比分析

为了解白皮大蒜和紫皮大蒜精油成分及生物活性差异,采用水蒸气蒸馏法提取白皮大蒜和紫皮大蒜精油,通过气相色谱质谱联用仪(GC-MS)分析测定两种大蒜精油的可挥发性成分;用对倍稀释法研究两种大蒜精油对几种常见病原菌的抑制活性;采用小叶碟法测定两种大蒜精油对斜纹夜蛾的拒食活性;并检测白皮、紫皮大蒜精油对ABTS、DPPH和OH自由基的清除作用。结果表明:白皮大蒜精油鉴定出26种成分,占精油的95.79%;紫皮大蒜精油鉴定出22种成分,占精油的94.26%,主要杀菌物质大蒜辣素和大蒜新素在紫皮大蒜(59.34%)中的含量比白皮大蒜(50.11%)多;两种大蒜精油对实验用菌有明显抑制作用,尤其紫皮大蒜精油对枯草芽孢杆菌、白色念珠菌、热带假丝酵母菌和板栗疫病的抑制效果比白皮大蒜好;白皮大蒜和紫皮大蒜精油对斜纹夜蛾24h平均拒食率分别为52.97%和100%;白皮大蒜精油对ABTS和DPPH自由基的清除率高于紫皮大蒜精油,对OH自由基的清除率基本相当。     

玉米淀粉对大蒜中大蒜素的包合及其复合物的抑菌活性

以玉米淀粉和鲜大蒜为原料,尝试高速剪切混合制备淀粉-大蒜素复合物,并对其抑菌活性进行评价。结果表明,当高速剪切混合处理时间为40 min,大蒜(干基)/淀粉质量比为3:2时,复合物中大蒜素的含量为1.17±0.02μg/mg,包埋率为89.71%±1.20%。碘结合实验表明,淀粉与大蒜中的大蒜素通过主客体相互作用形成复合物。玉米淀粉经高速剪切混合处理后颗粒形态的变化不大,但是与大蒜共同处理后淀粉颗粒的形态发生较大的变化。形成复合物后淀粉的结晶度降低;淀粉复合物比大蒜粉具有较高的热稳定性。抑菌实验表明,复合物的抑菌活性良好,当大蒜(干基)与玉米淀粉质量比为3:2时,其对E.coli,S.aureus,B.subtilis和S.Typhimurium的抑菌圈直径分别为19.92±0.03、23.02±0.03、34.51±0.20、23.21±0.15 mm。淀粉-大蒜素复合物的形成,提高了大蒜素的生物活性。     

Formation,nutritional value,and enhancement of characteristic components in black garlic: A review for maximizing the goodness to humans

Black garlic (BG) is essentially a processed food and obtained through the transformation of fresh garlic (FG) (Allium sativum L.) via a range of chemical reactions (including the Maillard reaction) and microbial fermentation. This review provides the up‐to‐date knowledge of the dynamic and complicated changes in major components during the conversion of FG to BG, including moisture, lipids, carbohydrates (such as sugars), proteins, organic acids, organic sulfur compounds, alkaloids, polyphenols, melanoidins, 5‐hydroxymethylfurfural, vitamins, minerals, enzymes, and garlic endophytes. The obtained evidence confirms that BG has several advantages over FG in certain product attributes and biological properties (especially antioxidant activity), and the factors affecting the quality of BG include the type and characteristics of FG and processing technologies and methods (especially pretreatments, and processing temperature and humidity). The interactions among garlic components, and between garlic nutrients and microbes, as well as the interplay between pretreatment and main manufacturing process, all determine the sensory and nutritional qualities of BG. Before BG is marketed as a novel snack or functional food, more research is required to fill the knowledge gaps related to quantitative monitoring of the changes in metabolites (especially those taste‐active and/or biological‐active substances) during BG manufacturing to maximize BG's antioxidant, anticancer, antiobesity, anti‐inflammatory, immunostimulatory, anti‐allergic, hepatoprotective, cardioprotective and oxidative stress‐/hangover syndrome‐reducing functions, and beneficial effects on memory/nervous systems. Assessments of the quality, efficacy, and safety of BG should be performed considering the impacts of BG production conditions, postproduction handling, and intake methods.     

Effects of garlic oil on milk fatty acid profile and lipogenesis‐related gene expression in mammary gland of dairy goats

BACKGROUND: Garlic oil (GO) has blood lipid‐lowering effects. Milk fatty acid (FA) originates partly from plasma, and can be affected by the mammary lipogenesis. This study aimed to investigate GO effects on milk FA profile and mammary lipogenesis‐related gene expression. Early‐lactation goats were randomly allocated to four treatments with six goats each, and offered corn silage ad libitum and fixed amount of 0.79 kg day^?1 dry matter (DM) concentrate mixed with GO (0, 0.57, 1.14, 1.71 g kg^?1 DM) for 30 days consisting of 26‐day adaptation. RESULTS: Intake of corn silage reduced (P≤0.05) as GO level increased in the concentrate. Lipase activity and lactose content linearly increased, while non‐esterified FA concentration quadratically decreased with increasing GO level (P≤0.05). The proportions of short‐ and medium‐chain (C14:0, C15:0 and C16:0) and saturated FA decreased, whereas C18, cis9 trans11 conjugated linoleic acid (c9t11 CLA), t10c12 CLA, monounsaturated and polyunsaturated FA, and some ≥ C20 FA proportions increased in a linear manner with increasing GO level (P≤0.05). The mRNA abundance of genes remained unchanged (P > 0.1) as GO level increased. CONCLUSION: Garlic oil altered milk FA profile and these effects may not be related to the mammary lipogenesis‐related genes expression. © 2012 Society of Chemical Industry     

A comparative study on the antioxidative and anti‐allergic activities of fresh and aged black garlic extracts

The antioxidative and anti‐allergic activities of fresh and aged black garlic extracts were investigated. The garlic samples were extracted with 70% ethanol (v/v) and the total phenolic content was measured. The antioxidant capacity of extracts was assessed by determining the scavenging activities on 1,1‐diphenyl‐2‐picrylhydrazyl and hydroxyl radicals, ferricyanide reducing power, ferrous ion‐chelating ability and inhibitory effect on linoleic acid peroxidation. The anti‐allergic activity of extracts was analysed by measuring their inhibitory effects against β‐hexosaminidase release. The aged black garlic exhibited significantly higher phenolic content and greater antioxidative activity than fresh garlic. Both garlic extracts showed strong antioxidant capacity in a dose‐dependent manner. On the other hand, a considerably higher suppression of β‐hexosaminidase release was found in fresh garlic extract at lower concentration compared with that of the black garlic. Results of this study illustrate that ageing of garlic could enhance its antioxidant capacity, but could decrease its anti‐allergic activity.     

INSTRUCTIONS FOR PREPARATION OF MANUSCRIPTS FOR DIRECT REPRODUCTION

ABSTRACT

The bulk density of garlic slices at different moisture levels (ranging from approximately 3 to 65% MC wet basis) was determined by weighing the contents of a container of known volume. The porosity was calculated using its relationship with bulk and apparent densities. An analysis of variance (ANOVA) revealed that bulk density and porosity were affected significantly by moisture and slice thickness as well as the interaction of these variables. Bulk density varied in a positive linear fashion with moisture and thickness while a negative linear correlation was found for the calculated bulk porosity. The linear model met me adequacy criterion for characterising the behaviour of garlic. Using a laboratory unit, the vertical resistance to airflow through the product and die effect of moisture and slice thickness were investigated for an airflow rates of 0.09 to 1.2 m³/s-m². A higher resistance to airflow was noted for the wet product with the experimental data fitting to Shedd's model when the airflow range was divided into two sub-flow rates and to a modified Ergun's equation for the full range.     

蒜素快速检测方法的建立及应用

建立了一种测定鲜蒜中蒜素(二烯丙基硫代亚磺酸酯)含量的高效液相色谱分析方法.样品提取后以C18柱(250 mm×4.6 mm,5μm)为色谱柱分离,以乙腈与0.1％甲酸为流动相进行梯度洗脱,流速为1.0 mL/min,检测波长为245 nm,进样量为10μL,色谱柱温度为40℃.对鲜蒜试样进行3个浓度水平3个重复的添加试验,得到平均回收率为95.5％～106％,相对标准偏差为1.39％～2.83％.线性范围为10～500mg/L.该方法具有样品预处理简单、灵敏度较高等优点.     

Evaluation of pre‐heating and extraction solvents in antioxidant and antimicrobial activities of garlic,and their application in fresh pork patties

The objectives of this study were to screen the optimum conditions for antioxidant and antimicrobial activities of garlic as affected by pre‐heating and different extraction solvents, and to evaluate the antioxidant and antimicrobial effects of these extracts in ground meat during refrigerated storage. Methanol extracted garlic had a greater total phenolic content, 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH)‐radical scavenging activity and reducing power than water extracted one (P < 0.05), whereas the latter had a greater yield and iron chelating ability than the former (P < 0.05). Moreover, water extract from fresh garlic (WEFG) and methanol extract from heated garlic (MEHG) produced an inhibition zone against Escherichia coli O157:H7 and Listeria monocytogenes. The addition of garlic extracts (WEFG, MEHG and their combinations WEFMEHG)) to pork patties decreased the pH, hunter a values (redness), thiobarbituric acid substances values and the number of total plate count and Enterobacteriaceae (P < 0.05), while the hunter b values (yellowness) increased (P < 0.05). Results of this study indicated that the use of the garlic extracts was able to control lipid oxidation and microbial growth in pork patties.