Evaluation of enzyme-assisted extraction on quality of garlic volatile oil

Application of enzymes to garlic prior to steam distillation/hydrodistillation resulted in a two fold increase in the yield of oil. The oil yield in case of cellulase, pectinase, protease and viscozyme pretreatment was in the range of 0.39–0.51%, as against 0.28% in a control sample by steam distillation, and in the range of 0.45–0.57% by hydrodistillation as against 0.31% in a control sample. Profiling of the garlic oil thus obtained was carried out by GC–MS. Di-2-propenyl trisulfide (52%) along with the corresponding di- and tetra-sulphides (11% and 5%) constituted the major portion of the oil. The other major flavour compounds identified were methyl 2-propenyl trisulfide (11.8%), vinyl dithiins (9.9%) and dithianes (4.1%). The studies demonstrate that enzymes facilitate the extraction of garlic oil, resulting in an increase in the yield of oil, with little change either in flavour profile or physicochemical properties of the oil.     

Antioxidant Functions of E- AND Z-Ajoene Derived from Japanese Garlic

Antioxidative activities of E- and Z-ajoene prepared from Japanese garlic were studied using various radical scavenging effects. Among the various antioxidative activities tested, ajoene was found to show the highest hydroxyl radicals scavenging activity (E-ajoene = 50% and Z-ajoene = 63%). These ajoene were 5.2-13 times less efficient at reducing DPPH radical and 1.1-1.4 times less efficient at hydroxyl radical as compared with authentic α–tocopherol. Essentially E- and Z-ajoene were capable of scavenging superoxide anion (E- ajoene = 0.11%, Z-ajoene = 3.74%), but 80 minutes later antioxidant activity could not be detected. The effectiveness of Z-ajoene is significantly higher than E-ajoene.     

发酵方式对蔬菜质构和抗氧化性的影响

研究了5%NaCl腌渍预处理、发酵温度对白菜和大蒜泥混合物质构和抗氧化性能的影响。结果表明,腌渍预处理可改善产品质构,处理后半固态发酵与固态发酵产品质构无显著差异。腌渍预处理后接种乳酸菌对混合物进行发酵,得到的产品其甲醇提取物浓度是8mg/mL时,还原力是α-生育酚和丁基羟基茴香醚(BHA)的1.2～1.6倍;浓度是2mg/mL时,半固态发酵产品的2,2-二苯代苦味酰基苯肼(DDPH)自由基清除力是76.1%,固态发酵产品的是80.5%。     

Enzyme inactivation kinetics and colour changes in Garlic (Allium sativum L.) blanched under different conditions

The inactivation kinetics of the enzymes peroxidase, polyphenoloxidase and inulinase and changes in the color parameters L^∗, a^∗ and b^∗ of garlic cloves cut in slices, were studied during steam blanching at 100 °C and water at 80 and 90 °C. The garlic cloves were peeled, cut into slices and distributed uniformly in metal baskets and one batch placed in an autoclave generating steam at a temperature of 100 °C; and the others in water baths at 80 and 90 °C. The best blanching conditions were in steam for 4 min, where no changes in texture were observed, and the enzymatic activities were reduced by 93.53%, 92.15% and 81.96% for peroxidase, polyphenoloxidase and inulinase, respectively. Under these conditions the inulin concentration reduced by 3.72%. The color parameter L^∗ increased with increase in blanching time, the samples becoming lighter in color, and the parameters a^∗ and b^∗ decreased, obtaining slices that were greener and bluer.     

Physicochemical and release characterisation of garlic oil-β-cyclodextrin inclusion complexes

Garlic oil (GO), rich in organosulphur compounds, has a variety of antimicrobial and antioxidant activities, however, its volatility and low physicochemical stability limit its application as food functional ingredients. The aim of this study was to investigate the physicochemical and release characterisation of inclusion complexes of GO in β-cyclodextrin (β-CD). The formation of GO/β-CD inclusion complex was demonstrated by different analytical techniques including Fourier transform-infrared spectroscopy, differential scanning calorimetry and X-ray diffractometry. The stoichiometry of the complex was 1:1. The calculated apparent stability constant of GO/β-CD complex was 1141 M⁻¹, and the water solubility of GO was significantly improved by the phase solubility study. Furthermore, the release of GO from the inclusion complex was determined at a temperature range from 25 to 50 °C and in an acidic dissolution medium (pH 1.5), respectively. The release rate of GO from the inclusion complex was controlled.     

Preliminary investigation of the effects of low-level dietary inclusion of fragrant essential oils and oleoresins on pig performance and pork quality

Since the tissue characteristics of monogastric species are readily influenced by the composition of the feeds they consume, the objectives of this preliminary study were to assess the performance of finisher pigs on diets containing 0.05% of essential oils or oleoresins of rosemary, garlic, oregano, or ginger, and to determine the effect of these diets on pork quality. The pigs preferred the garlic-treated diet, and feed intake and average daily gain were significantly increased although no difference in feed efficiency was observed. Carcass and meat quality attributes were unchanged by dietary treatment, although a tendency towards reduction of lipid oxidation was noted in oregano-fed pork. Sensory panelists were unable to detect a flavour/aroma difference between treated and control pork. These results indicate that a higher level of dietary supplementation may be required in order to effect observable differences in pork characteristics.     

γ-谷氨酰转肽酶与蒜泥绿变的关系

本文研究了γ－谷氨酰转肽酶与蒜泥绿变的关系，测定了不同休眠期、不同温度贮藏不同时间的大蒜中γ－谷氨酰转肽酶的活性，并将从发芽的大蒜中所制备的γ－谷氨酰转肽酶添加到不能绿变的蒜泥中，确定了γ－谷氨酰转肽酶对蒜泥绿变的作用。     

Diatomaceous earth enhances the toxicity of garlic, Allium sativum, essential oil against stored-product pests

Laboratory bioassays were carried out to determine the efficacy of garlic, Allium sativum L. (Amaryllidaceae), essential oil applied alone or with diatomaceous earth (DE) against adult rice weevils, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and red flour beetles, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). The results showed that the combination treatment was significantly more effective than either treatment alone. In addition, the results also showed that the simultaneous application of essential oil plus DE significantly reduced the concentration of essential oil alone required for an effective treatment and the application rate of DE can be reduced when combined with essential oil. Moreover, the activity of the combination treatment lasted longer than that of essential oil alone and the survival of eggs or larvae to adult stage was significantly inhibited in the combined treatments against both species, compared with the use of essential oil alone. Our results suggested that garlic essential oil combined with DE has a strong additive effect, and therefore may have potential as an alternative to synthetic insecticides for the control of insect pests of stored products.     

Effect of sage and garlic on lipid oxidation in high-pressure processed chicken meat

Sage was found to protect minced chicken breast processed with high hydrostatic pressure up to 800 MPa for 10 min against lipid oxidation during subsequent chilled storage for 2 weeks. Garlic showed prooxidative effects especially at moderate high pressure around 300 MPa, an effect partly counteracted by simultaneous addition of sage. From the rate of lipid oxidation, measured as thiobarbituric acid reactive substances, the apparent volume of activation for pressure-induced lipid oxidation during subsequent chilled storage was estimated, which showed that the prooxidative effect of garlic and pressure-induced lipid oxidation were additive. Based on electron spin resonance (ESR) spectroscopy radical formation was measured in pressurized lipid and aqueous phases of minced chicken thighs, and a high radical scavenging capacity of sage in the lipid phase was identified as most important for the protective effect of sage.