Polyphenol Oxidase from Bean Sprouts (Glycine max L.)

ABSTRACT: Polyphenol oxidase (PPO) was purified and characterized from bean sprouts by ammonium sulfate precipitation, DEAE‐Toyopearl 650M, CM‐Toyopearl 650M, SuperQ‐Toyopearl 650S and QAE‐Toyopearl 550C column chromatographies. Substrate staining of the crude extract on electrophoresis showed the presence of 2 isozymic forms of this enzyme. The molecular weight of the purified enzyme was estimated to be about 54 kDa. The optimum pH was 9.0 and optimum temperature 40 °C. Heat inactivation occurred about 30 °C. PPO showed activity to catechol, pyrogallol and dopamine. These compounds such as ascorbic acid, L‐cysteine, 2‐mercaptoethanol, and glutathione used was the effective inhibitor. Enzyme activity was maintained for 7 d at 4 °C but suddenly decreased after 8 d.     

发酵与发芽处理对绿豆淀粉黏度性质的影响

将绿豆进行发酵及发芽处理,研究不同处理对绿豆淀粉黏度的影响。采用快速黏度分析仪（RVA）测定了不同处理的绿豆淀粉糊化特性。结果表明自然发酵对绿豆淀粉黏度影响不大,只有峰值黏度略有下降：生物混合发酵可使样品的峰值黏度和热浆黏度均出现较大幅度的下降,最终黏度下降。绿豆发芽后提取的淀粉其黏度变化较大,其峰黏度上升1248．00mPa·s,热浆黏度上升698．00mPa·s,淀粉的黏度显著上升。     

Comparative Studies on Physico-Chemical Properties of Starches from Jackfruit Seed and Mung Bean

The physico-chemical properties of starch from jackfruit seed and mung bean were investigated. Jackfruit seed starch had much higher resistant starch content (26.99%) than that of mung bean starch (4.04%). Furthermore, jackfruit seed starch had a higher gelatinization temperature (T_o) that required more gelatinization energy (ΔH) compared to mung bean starch. However, mung bean starch had higher amylose content and its granules were much larger than that of jackfruit seed starch. Mung bean starch had the highest peak viscosity, breakdown, and setback whereas jackfruit seed starch had the highest pasting temperature. Amylopectin chain length of mung bean starch contained higher proportion of short chains (degrees of polymerization 6–12) but lower proportion of very long chains (degrees of polymerization > 37 ) comparing with jackfruit seed starch. The X-ray diffraction patterns showed both starches to be Type-A crystallinity. In addition, both starch gels showed higher the storage modulus (G′) than the loss modulus (G?) designating as rubber like material. However, mung bean starch gel exhibited higher G’ and less tan δ than that of jackfruit seed starch indicating much stronger of gel structure.     

不同发芽条件对蚕豆植酸酶活性的影响

以蚕豆为试材,研究发芽过程中植酸酶在蚕豆不同部位的变化和性质.发芽蚕豆不同部位植酸酶活性呈现先高后低的变化趋势,子叶植酸酶在发芽第6天达最高值.超声波处理对发芽蚕豆胚根、子叶和胚芽植酸酶活性有一定促进作用,其中以15min超声波处理对胚根和胚芽植酸酶活性影响最大,5min处理、10min处理和15min处理均对子叶植酸酶活性有显著影响.在发芽过程中不同光照对蚕豆进行处理,不论胚根、子叶还是胚芽,黑暗处理植酸酶活性高于光照处理.核酸抑制剂放线菌素(Act-D)和蛋白质抑制剂环已酰胺(CHM)对发芽蚕豆胚根、子叶和胚芽中的植酸酶活性有一定影响,其中以CHM的抑制效果最为明显.     

A Rapid High-Performance Liquid Chromatography Photodiode Array Detection Method to Determine Phenolic Compounds in Mung Bean (Vigna radiata L.)

A fast method was developed for simultaneous detection and quantification of 12 phenolic compounds in mung bean, using reversed phase high-performance liquid chromatography. The method was optimized for mobile phase combination, elution gradient, detection wavelength, and solvent extraction. All the phenolic compounds (gallic acid, neochlorogenic acid, catechin, chlorogenic acid, caffeic acid, p-coumaric acid, t-ferulic acid, vitexin, isovitexin, myricetin, quercetin, and kaempferol) were eluted for 18 min and recovered within a limit as per International Council for Harmonization guidelines. The method showed good linearity with correlation coefficient of 0.998. The limit of detection and quantification of all the compounds ranges from 0.27 ± 0.01 to 3.65 ± 0.3µg/mL and 0.91 ± 0.1 to 12.17 ± 0.9µg/mL, respectively. Vitexin (28.10 ± 0.20 to 29.60 ± 0.6 mg/100 g raw material) and isovitexin (34.09 ± 0.14 to 36.83 ± 0.82 mg/100 g raw material) were the major phenolic compounds along with other phenolic compounds found in mung beans.     

Fermentation and enzyme treatment of tannin sorghum gruels: effects on phenolic compounds,phytate and in vitro accessible iron

The presence of polyphenols and phytate in cereal products has been shown to interfere with the bioavailability of minerals such as iron. In the present study, we added enzymes (wheat phytase and mushroom polyphenol oxidase) during fermentation of tannin sorghum gruels prepared from flour with or without addition of 5% flour of germinated tannin-free sorghum grains (power flour), and investigated the effects on phenolic compounds, phytate and in vitro accessible iron. Assayable phenolic compounds were significantly reduced by fermentation, with high reductions observed in gruels with added enzymes. Fermentation of the gruels with addition of enzymes reduced (on average) total phenols by 57%, catechols by 59%, galloyls by 70% and resorcinols by 73%. The phytate content was significantly reduced by fermentation (39%), with an even greater effect after addition of power flour (72%). The largest reduction of phytate (88%) was, however, obtained after addition of phytase. The in vitro accessible iron was 1.0% in the sorghum flour and it increased after fermentation with power flour and/or with enzymes. The highest in vitro accessibility of iron (3.1%) was obtained when sorghum was fermented with addition of power flour and incubated with phytase and polyphenol oxidase after the fermentation process.     

浸泡处理对红芸豆的物理性质及蒸煮品质的影响

以红芸豆为原料,探讨不同浸泡温度(25、45、65℃)对芸豆物理性质及蒸煮品质的影响。结果表明:芸豆在浸泡过程中,随着浸泡温度升高与时间延长,其吸水率、体积膨胀率、固形物溶出率等均呈增加的趋势,平衡吸水率常数则呈下降趋势;浸泡温度的提高有利于达到浸泡平衡及缩短浸泡时间。在加工性能方面,45℃下浸泡可显著缩短煮豆时间并提高煮熟红芸豆的品质。     

The purification and characterisation of polyphenol oxidase from green bean (Phaseolus vulgaris L.)

Four isoforms of polyphenol oxidases (PPOs) were characterised in purified extracts of coats (PPOIa and PPOIb) and pods (PPOIIa and PPOIIb) of green bean (Phaseolus vulgaris L.). The molecular weights of four isoforms have been estimated to be from 57.5 to 39.0 kDa by SDS–PAGE. The PPOII (mixture of PPOIIa and PPOIIb) was used to characterise the PPO of green bean pods. All isoforms activities were stable between pH 6.8 and pH 7.2. PPOIa and PPOII have similar thermal inactivation profiles, and PPOIb has higher thermal stability than that of PPOIa and PPOII. PPOs showed the highest affinity to pyrogallol in all selected substrates. Although activities of PPOs were markedly inhibited by l-ascorbic acid, the activity of PPOI (mixture of PPOIa and PPOIb) was significantly activated by MnSO₄ and CaCl₂.     

番石榴多酚氧化酶的部分纯化及其特性研究

番石榴PPO的粗提取液经过80%硫酸铵盐析和DEAE-Toyopearl 650M、CM-Sephadex C-50离子交换柱层析分离后,被纯化了约126倍,回收率为16.13%。该酶迅速地催化焦性没食子酸的酶促氧化反应,而对对苯二酚和绿原酸则完全无催化活性。该酶对焦性没食子酸的Km值为4.6 mmol/L,其最适pH为7.5,pH稳定性范围在pH4.0~11.0,最适温度为50℃,热稳定性相对较高,在≥90℃加热10 min后仍残留约15%的酶活性。该酶的最佳抑制剂是抗坏血酸和NaHSO3,其次是植酸、盐酸-L-半胱氨酸、柠檬酸,Ca2+、Mg2+等金属离子对该PPO也有较强的抑制作用。     

小麦多酚氧化酶(PPO)活性的基因型、环境及其互作效应的分析

选用16个有代表性的小麦品种(系)，分别在山东8个地区进行小麦多酚氧化酶(PPO)活性的基因型与环境效应分析。结果表明，在随机效应中，小麦籽粒PPO活性的品种与试点互作效应最为显著。在对面团白度性状进行选择时，既要选择多酚氧化酶(PPO)活性低的品种，又要注意选择在PPO积累低的地区种植，以实现优质品种的优质生产。     

Effect of Soaking and Cooking on the Oligosaccharide Content of Dry Beans (Phaseolus vulgaris, L.)

The effect of cooking conditions commonly used in Brazilian homes was determined by measuring the oligosaccharide content (sucrose, raffinose and stachyose) of beans (Phaseolus vulgaris, L.) by thin-layer chromatography. Soaking in water caused a small decrease in the oligosaccharide content of the beans and the relative amount removed was not proportional to the solubility of the sugars in water. Cooking of the whole seeds led to a larger decrease in oligosaccharide content, especially when large amounts of water were used.     

Functional and Nutritional Properties of Extruded Whole Pinto Bean Meal (Phaseolus Vulgaris L.)

Pinto bean meals with 18, 20, and 22% moisture were extruded at 140,160 and 180°C, using screw speeds of 150,200 and 250 rpm in a single-screw laboratory extruded. Expansion index, bulk density, water absorption and solubility indices, in vitro protein digestibility, and trypsin inhibitor activity in extrudate were measured. Temperature and feed moisture influenced (p<0.05) expansion index, bulk density, water absorption index and in vitro protein digestibility. Water solubility index was affected by temperature only. Trypsin inhibitors were inactivated completely for all conditions. Screw speed had no effect on any dependent variable. Best product was produced with 22% feed moisture at 160°C.     

热烫处理对黑莓果汁营养成分和多酚氧化酶活力的影响

黑莓榨汁前采用蒸汽热烫处理,可以明显提高果汁中功能性成分———花色苷和总酚的含量,并且可以使导致果汁褐变和品质下降的主要内源酶多酚氧化酶失活,热烫3min,压榨得到果汁的花色苷和总酚含量达到最高值,当热烫时间2min,黑莓中的多酚氧化酶已完全失活。随着热烫时间延长,果汁出汁率有所下降。添加0.05%Vc进行护色处理,不能促进花色苷和总酚的溶出。黑莓榨汁前最佳的蒸汽热烫处理时间为3min。     

桑叶多酚氧化酶分离及活性研究

采用分光光度法和扫描电子显微镜对桑叶多酚氧化酶(PPO)的结构、活性以及不同抑制剂的抑制效果进行研究。结果表明:桑叶多酚氧化酶为纤维状蛋白;其最适pH值为7.0,最适温度为40℃;在相同抑制剂浓度下,总体抑制效果为:抗坏血酸>亚硫酸氢钠>柠檬酸>氯化镁>氯化钠。     

Polyphenol oxidase activity,phenolic acid composition and browning in cashew apple (Anacardium occidentale, L.) after processing

This study describes the extraction and characterisation of cashew apple polyphenol oxidase (PPO) and the effect of wounding on cashew apple phenolic acid composition, PPO activity and fruit browning. Purification factor was 59 at 95% (NH₄)₂SO₄ saturation. For PPO activity, the optimal substrate was catechol and the optimum pH was 6.5. PPO K_m and V_max values were 18.8 mM and 13.6 U min⁻¹ ml⁻¹, respectively. Ascorbic acid, citric acid, sodium sulphite and sodium metabisulphite decreased PPO activity, while sodium chloride increased PPO activity. Wounding at 2 °C and 27 °C for 24 h increased PPO activity but storage at 40 °C reduced PPO activity. Gallic acid, protocatechuic acid and cinnamic acid (free and conjugate) were identified in cashew apple juice. Cutting and subsequent storage at 40 °C hydrolysed cinnamic acid. 5-Hydroxymethylfurfural content in cashew apple juice increased after injury and storage at higher temperatures, indicating non-enzymatic browning.     

Effect of feeding tannic acid and kidney bean (Phaseolus vulgaris) on the intestinal absorption of D-galactose and L-leucine in chickens

Weight changes, food intake, in-vivo intestinal absorption of D -galactose (2.77mm) and L -leucine (5 mM) and in-vitro intestinal absorption of d-galactose (2 mm) were studied in male growing chickens fed ad libitum from hatching for periods of 21 and 49 days on 210 g kg^?1 protein diets containing either heated soya bean (HSB, control) with or without added tannic acid (25 and 30 g kg^?1) or raw kidney bean (RKB, Phaseolus vulgaris L) as the main sources of protein. As compared with HSB-fed birds, weight gain was significantly smaller (P <0.05) in the HSB + tannic acid- and RKB-fed birds; these chickens ate significantly more (P <0.05) than HSB-fed birds. Regardless of the number of days of feeding, both HSB + tannic acid- and RKB-fed birds showed a significant reduction (P <0.05) in the rates of in-vivo intestinal absorption of galactose and leucine and in-vitro intestinal absorption of galactose, as compared with HSB-fed chickens, these effects being especially marked in the RKB-fed birds. The possible implications of these findings are discussed.     

Thermal Effects on in vitro Protein Quality of Red Kidney Bean (Phaseolus vulgaris L.)

Significant thermal effects on in vitro protein quality of red kidney beans were observed. Beans autoclaved at 121°for 10 and 20 min, and common home-cooked beans had improved protein quality. Uncooked beans, and those autoclaved at 128°for 20 min and at 121°for 90 min had reduced protein quality compared to canned beans and those autoclaved at 110°for 20 min and at 121°for 40 and 60 min. Amino acid scores, essential amino acid index and available lysine (%), corrected for in vitro protein digestibility gave comparable results in evaluation of protein quality. Specific lysine, methionine, cysteine and other amino acid ratios overestimated protein quality.     

Mechanism of Browning in Fresh Highbush Blueberry Fruit (Vaccinium corymbosum L). Partial Purification and Characterisation of Blueberry Polyphenol Oxidase

The most efficient method for polyphenol oxidase (PPO) extraction from Highbush blueberry fruits was the preparation of an acetone powder. No activity was detected after direct extraction with phosphate buffer (pH 6·5) and detergents such as Triton X-100. PPO has been purified 19-fold, by ultrafiltration, ammonium sulphate precipitation and hydrophobic chromatography. Native-PAGE of the purified fraction revealed the presence of two isoforms. PPO has an observed optimum pH at 4·0, followed by a shoulder at pH 5·0. Caffeic acid is the best substrate (100%), followed by chlorogenic acid (60%) and pyrocatechol (32·5%). No activity was detected towards catechin, protocatechuic acid, resorcinol and monophenols. © 1997 SCI.     

微射流处理对红豆分离蛋白结构及功能特性的影响

采用高压微射流纳米均质机处理红豆分离蛋白,运用溶解度、比浊法、圆二色光谱法探讨了多次微射流处理对红豆分离蛋白构象和功能特性的影响规律.微射流处理诱导不溶性蛋白聚合物解聚,增加了蛋白质的溶解度,改善了蛋白的乳化活性指数;圆二色光谱分析表明,红豆蛋白的二级结构组成:α-螺旋结构为6.2％,β-类结构为59.3％,无规则卷曲...     

Effect of Germination on Chemical Composition,Biochemical Constituents and Antinutritional Factors of Soya Bean (Glycine max) Seeds

The published scientific data concerning the effects of germination on chemical composition, biochemical constituents and anti-nutritional factors of soya bean are reviewed. The amino acid profile did not change to a great extent; only a noticeable increase in aspartic acid was observed whereas there was a gradual decrease in the available lysine level and lipid content as germination progressed. Both the total protein content and the nonprotein nitrogen increased after 5 days of germination. Dietary fibres are partially degraded in germinated seeds. Germinated soya bean is an excellent source of ascorbic acid and riboflavin. Niacin contents increased distinctly after germination. Germination induced a reduction in lipase inhibitor activity. The galactosyl oligosaccharides drastically decreased in germinated seeds. After 4 days of germination, the activity of certain lectins decreased to 4% of that of ungerminated soya beans. The phytic acid in the seeds was degraded by the phytase activated during germination, thus increasing the availability of the minerals present in the germinated seeds. Germination can degrade both Kunitz soya bean trypsin inhibitor and the major Bowman–Birk soya bean trypsin inhibitor; the degradation is enhanced, if germination process lasts more than 4 days. © 1997 SCI.