ANTIOXIDANT AND FREE RADICAL SCAVENGING ACTIVITIES OF EDIBLE MUSHROOMS

The antioxidative potency of commercially available mushrooms in Taiwan was studied. The free radical scavenging activities of these mushrooms were demonstrated by using the DPPH method. The antioxidative activities of ethanol extracts of various mushrooms in an emulsified corn oil (o/w) system at 60C were compared. The addition of test compounds in corn oil emulsions significantly extended the induction period of lipid oxidation. The order of inhibitory activity of mushroom extracts on oxidation in emulsion system was Agaricus bisporus > Hypsizigus marmoreus > Volvariella volvacea > Flammulina velutipes > Pleurotus eryngii > Pleurotus ostreatus > Hericium erinaceus > Lentinula edodes. In the thermal oxidative stability test, using lard, the order of antioxidative activity of test materials showed similar tendencies, except for the extract of Lentinula edodes.     

THE INFLUENCE OF MICROWAVES AND SELECTED MANUFACTURING PARAMETERS ON APPLE CHIP QUALITY AND ANTIOXIDANT ACTIVITY

Apple chips belong to the group of low-processed food products and are an interesting alternative to currently popular snacks. The aim of the work was to estimate the influence of chosen technological parameters on quality and antioxidant properties of apple chips. Thickness of apple slices, drying temperature and initial microwave treatment were analyzed.
On the basis of experimental data, it was established that the drying temperature of 90C was optimal for obtaining products with advantageous sensory value. Apples before drying should be cut into slices 3.5 mm thick and immediately soaked in a solution containing saccharose, apple concentrate, citric acid and SO₂. It was shown that microwave pretreatment of apple slices (150–300 W, 5–10 min) shortened the drying time by about 25% and increased the antioxidant potential by about 30%.

PRACTICAL APPLICATIONS

Because of the increasing incidence of civilization diseases, worldwide interest in snack products that are low in calories and healthy is still growing. The optimum parameters of apple chip production (slice thickness and drying temperature) to obtain a product of high antioxidant potential are presented in this study. It is also shown that application of microwave pretreatment enabled us to shorten the process duration and to reduce the production costs while antioxidant activity remained at a relatively high level.     

海带中褐藻糖胶的提取及其对自由基清除能力的研究

以海带为原料提取褐藻糖胶，并初步研究了一些因素对褐藻糖胶的自由基清除能力的影响。研究表明，褐藻糖胶的最佳提取温度为100℃，提取时间为6h，加水量为90mL/g，得率为11．05％，温度对自由基清除能力影响不大，浓度与自由基清除能力正相关。     

CHEMICAL COMPOSITION AND ANTIOXIDANT ACTIVITY OF SAPOTA (ACHRAS SAPOTA LINN.) FRUIT

Sapota (Achras sapota Linn.) belongs to the family Sapotaceae and is assigned for various properties in the traditional system of Indian medicine. For the first time, nutritional quality and antioxidant activity of sapota juice with reference to its chemical composition have been investigated employing various well‐established in vitro methods. Chemical composition analysis of sapota juice revealed that it is one of the rich sources of sugars, proteins, ascorbic acid, phenolics, carotenoids and minerals like iron, copper, zinc, calcium and potassium. Apart from the nutritional components just given, sapota juice showed potential antioxidant activity against 1,1‐diphenyl‐2‐picrylhydrazyl free radicals and superoxide radicals. Sapota juice potentially inhibited the free radical‐mediated lipid peroxidation in a liposome model system. Total reducing‐power assay revealed the potential reducing power of sapota juice. The multiple radical‐scavenging potential of sapota juice was found to be due to its nutraceutical components, viz., phenolics, carotenoids and ascorbic acid.     

COMPARISON OF CHEMICAL COMPOSITION AND ANTIOXIDANT ACTIVITY OF GLYCOSIDICALLY BOUND AND FREE VOLATILES FROM CLOVE (EUGENIA CARYOPHYLLATA THUNB.)

The present article reports on the chemical composition and antioxidant activity of clove glycosidically bound volatile compounds in comparison with their essential oil. The comparison of chemical composition of volatile aglycones with the chemical composition of essential oil revealed only eugenol as identical. To measure the antioxidative activity of the clove enzymatically released aglycones and its essential oil, two different assays were performed: the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging method and the ferric reducing/antioxidant power (FRAP) assay. Both methods showed that the clove volatile aglycones possess lower antioxidant properties than its essential oil. The volatile aglycones radical-scavenging activity measured by DPPH method was lower than butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) activity. The reducing capacity measured by FRAP method for volatile aglycones was lower than BHA capacity and higher than BHT capacity. Some differences in activity obtained by two methods could be explained with different solvent polarity.

PRACTICAL APPLICATIONS

Many secondary metabolites are glycosylated and accumulate as nonvolatile glycosides. Since the glycosides are able to release their aglycones by enzymatic hydrolysis, these compounds could be considered as possible precursors of antioxidant substances in plant. They may contribute to the total antioxidant activity of plant and could be used as natural antioxidants.     

SELECTED PHYSICAL AND MECHANICAL PROPERTIES OF COMMERCIAL APPLE CULTIVARS1

The compressive modulus of deforatability, strength and strain of failure of apple flesh of 12 commercial apple cultivars were determined using a Universal Testing Machine. The deformability modulus, calculated from the linear part of the corrected stress-Hencky's strain relationship was between 1.5 to 2.3 MPa with a coefficient of variation of 9–26%. The apparent upper limit of the strain in the linear region was on the order of 0.08–0.2. The compressive strength was on the order of 160–280 kPa, with the Baldwin apples a notable exception with strength twice as large. Failure usually occurred at a strain of 0.12–0.16 with the exception of the Baldwin and Granny Smith apples for which failure occurred at a strain of 0.25 and 0.2, respectively. The variability in the failure parameters     

肉豆蔻精油抗氧化性能及清除自由基能力的研究

测定肉豆蔻精油(NEO)的总体抗氧化能力、清除超氧阴离子自由基能力、清除羟基自由基能力、抗亚油酸脂质过氧化能力和清除DPPH自由基能力.并与合成抗氧化剂BHT、PG进行比较,对NEO抗氧化和清除游离基活性进行评价.结果表明:NEO具有良好的抗氧化效果,在一定浓度范围内,NEO的抗氧化活性比BHT和PG大,其清除羟自由基、DPPH自由基和超氧阴离子自由基能力优于BHT和PG,但精油抑制亚油酸过氧化能力比BHT和PG略弱.     

竹黄多糖BSP-1的组成和抗氧化活性分析

对竹黄子实体总多糖进行提取,分离纯化出2种均一的组分BSP-1和BSP-2.采用气相色谱和凝胶渗透色谱研究BSP-1的组成和分子量,并研究其对猪油的抗氧化作用.结果表明:BSP-1分子量为45.64 ku,主要由葡萄糖和甘露糖组成,摩尔比为2.46:1,红外光谱分析表明含有B-糖苷键,体外抗氧化实验证明BSP-1具有一定的抗猪油自动氧化能力.     

ANTIOXIDANT ACTIVITY AND QUALITY OF SOY ENRICHED APPLE BAR

Antioxidant activity of a soy enriched apple bar (SEAB) prepared from the pulp of culled apples and soy protein isolate (3%) was determined using a ferric reducing antioxidant power (FRAP) assay. The antioxidant activity was 8500 μM g⁻¹ FRAP and phenol content was 175 mg 100 g⁻¹. The soy enriched apple bar had 20 fold protein and 1.6 fold higher antioxidant activity than the plain apple bar. No significant change in antioxidant activity and total phenols was recorded during storage at ambient (22–31C) or low (4±1C) temperatures. The pectin, protein and ascorbic acid contents decreased while nonenzymatic browning and total sugars increased significantly with increase in storage periods. The product was organoleptically acceptable and microbiologically safe after 180 days of storage. A shelf stable soy enriched apple bar with high antioxidant activity, phenol content and sensorial quality can be an ideal source of dietary antioxidants.     

香菇中一种抗氧化活性成分的分离及组成分析

香菇全体经浸提,匀浆,脱色等预处理,经DEAE纤维素柱及Ultrogel ACA-44凝胶柱层析得到一种具有高抗氧化活性的成分(Le-Ⅱ).其浓度为1 g/L时可完全清除1,1-二苯基苦基苯肼自由基(DPPH).Le-Ⅱ红外扫描有典型的多糖和蛋白质的吸收峰.氨基酸分析表明其氨基酸种类齐全,其中酸性氨基酸与中性氨基酸较多,蛋白质质量含量为14.29%.气相色谱测得单糖组成为鼠李糖,阿拉伯糖,甘露糖,葡萄糖,摩尔比为0.58:0.67:0.78:3.69.多糖质量含量为1.29%.β-消去反应表明Le-Ⅱ中存在O-型连接的糖蛋白.刚果红反应初步表明其多糖部分存在三股螺旋构象.     

三种软骨多糖清除自由基活性研究

通过3个化学模拟体系:DPPH·(1,2-二苯代苦味肼基自由基)、羟自由基(·OH)、超氧阴离子(O2-·),检测并比较3种软骨多糖提取物清除自由基能力的大小.研究结果表明:在3个体系中,3种软骨多糖浓度与其清除自由基能力大小呈现一定量效关系;并且当多糖浓度达到一定值时,鼻骨多糖清除自由基能力最强,肋骨多糖次之,喉管骨多糖最弱.     

苹果渣中总黄酮的超声波辅助提取及清除自由基活性研究

利用超声波辅助法提取苹果渣黄酮,对提取的苹果渣黄酮进行清除自由基活性试验.通过单因素试验,考察4个因素对黄酮提取率的影响.结果表明,苹果渣黄酮的最佳条件为:提取时间20min,超声波功率260W,提取温度55℃,料液比1 g:10 mL.在此条件下,通过实验验证得出,黄酮提取率平均值为2.5927%;当苹果渣黄酮浓度为0.085 1g/L时,苹果渣黄酮对DPPH自由基的清除率为52.50%.     

COMPOSITION OF MAJOR FLAVANONE GLYCOSIDES AND ANTIOXIDANT CAPACITY OF THREE CITRUS VARIETIES

This paper reported on the composition of major flavanone glycosides (FGs) and antioxidant capacity of three Chinese citrus varieties during maturity, namely, Ponkan (P; citrus poonensis Hort. ex Tanaka), Satsuma mandarin (S; citrus unshiu Marc.) and Huyou (H; citrus paradisi Macf. cv. Changshanhuyou). The results showed that citrus peel is a rich source of FGs. Total penolics contents (TPC) of methanol extract of P, S and H were determined. The total antioxidant capacity (TAC) of P, S and H extracts was compared based on vitamin C equivalent antioxidant capacity by 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH·), 2, 2 ' -azinobis (3-ethylbenzothiazoline-6-sulfonate) (ABTS ^·+ ), reducing power and ferric reducing antioxidant power (FRAP) assay. Phenolic compounds may contribute a lot to TAC of fresh fruits, especially for unripe fruits. The correlations among TPC, DPPH·, ABTS ^·+ , reducing power and FRAP assay were rather high ( P <  0.05).

PRACTICAL APPLICATION

Citrus flavonoids are abundant in citrus fruits, especially FGs, such as hesperidin and naringin; and they are attracting more attentions for their biological properties and health benefits. The sun-dried citrus peels ( chenpi ) are usually used in the traditional Chinese medicine for high content of hesperidin. Investigation on the composition of FGs in peel and edible part of citrus fruits during maturity is necessary to establish a database for the future use in health foods and ingredients. Meanwhile, four methods were employed simultaneously to achieve a comprehensive evaluation on the antioxidant capacity of the three citrus varieties. The high antioxidant potential of the three selected citrus varieties made them desirable for dietary prevention of cardiovascular and other diseases.     

COMPOSITION AND PASTING PROPERTIES OF STARCH FROM TWO COCOYAM CULTIVARS

ABSTRACT

The composition and pasting properties of starches from two cocoyam cultivars were evaluated and compared with cassava starch. The starch, amylose and amylopectin contents of Xanthosoma and Colocasia cultivars ranged from 79.2 to 79.8%, 23.3–23.6%, 56.1–56.2% and 77.6–77.8%, 25.4–25.7%, 52.1–52.2%, respectively. The Xanthosoma and Colocasia starches had significantly low levels (0.12–0.24%) of lipid, with trace concentrations of crude fiber. Manihot utilissima had significantly (P ≤ 0.05) higher starch and amylopectin but lower amylose contents than Colocasia and Xanthosoma starches. Average granule sizes of Xanthosoma and Colocasia starches ranged from 4.3 to 5.6 µm and 2.5–3.4 µm, respectively. Xanthosoma and Colocasia starches showed restricted swelling and solubility patterns with high initial gelatinization temperatures ranging from 78.3 to 78.5C and 74.6–74.8C, respectively. Between 19.0–19.2% and 16.8–17.1% soluble carbohydrates were obtained from Xanthosoma and Colocasia starches, respectively, at 95C. The Xanthosoma starches had higher peak, hot paste and cooked paste viscosities and stability than Colocasia starches.

PRACTICAL APPLICATIONS

This study shows that the application of cocoyam starches in food would depend largely on the knowledge of their physicochemical properties which differed with the cultivars. The properties of importance include composition, granular characteristics, swelling, solubility and pasting characteristics. The low lipid content of Xanthosoma and Colocasia starches was important to their functionality because lipid complexes with carbohydrates and reduce swelling and solubility of starches by restricting gelatinization. Xanthosoma starches had significantly higher amylopectin but lower amylose contents than Colocasia starches. The relatively high amylose contents and smaller granular characteristics were associated with the low swelling and solubility patterns of starches from both cultivars. Xanthosoma starch had higher solubilities than Colocasia starch at higher temperatures (80–95C). Xanthosoma brasillience and Xanthosoma sagittifolium starches had superior viscosity stabilities than Colocasia antiquorum and Colocasia esculenta starches, and would be useful in baked products like biscuits, cakes and breads. C. esculenta and C. antiquorum starches would be desirable in sauces, soups and as thickeners in products requiring continuous heating and stirring where viscosity is not desired.