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1.
The effects of steep regime, nature of alkaline steeping agent, and kilning condition on α‐amylase development were studied for four Nigerian sorghum cultivars. Malt α‐amylase activity was highly significantly (p<.001) influenced by all the four factors as well as their various assortments of interaction. Generally malts from the Local Red (LR) variety produced the highest a‐amylase values, followed by those of SK 5912, Local White and KSV 8 in the above sequence. The presence/absence of air‐rest processes in steep regimes was a significant factor (p<.001) influencing malt α‐amylase response to final warm steeping as well as to the other factors under study. Similarly, the nature of the steeping agent was a very significant determinant of malt α‐amylase response to kilning condition and regime of steeping. Of significant interest was the observation that Ca (OH)2 steeps enhanced malt α‐amylase activity at the higher temperature of kilning. The significantly lower α‐amylase values given under similar conditions by the other alkaline liquors suggest a possible increase in malt thermostability due to steeping in Ca (OH)2. Additionally, the fact that the extent of enhancement of malt α‐amylase activity by Ca (OH)2, at 50°C Kiln temperature, was regime‐dependent, suggests that the latter was an important modulator of sorghum germination physiology.  相似文献   

2.
Steep regime, nature of alkaline liquor, and kilning conditions were studied for their effects on sorghum malt β‐amylase development in four Nigerian sorghum cultivars. Malt β‐amylase activity was markedly (p < .001) influenced by all the four factors as well as their various interactions. Overall, malts from KSV 8 variety were the most β‐amylolytic followed in sequence by those from Local Red (LR), SK 5912, and Local white (LW) respectively. The presence or absence of air rests in steep regimes was a significant (p < .001) determinant of sorghum β‐amylase response to final warm steeping, steep liquor and kilning condition. The nature of the alkaline steep liquor was also a major determinant of the pattern of malt β‐amylase response to the kilning condition. Steeping in Ca(OH)2 enhanced malt β‐amylase activity at the higher temperature of kilning, while KOH produced the opposite effect. Ca(OH)2 enhancement of β‐amylase development, at a kilning temperature of 50°C, was variety‐dependent suggesting that different sorghum cultivars may employ different biosynthesis models for β‐amylase synthesis. The regime‐dependence of β‐amylase response to kiln temperature suggests that this was an important modulator of sorghum germination physiology.  相似文献   

3.
In previous studies, Bacillus subtilis has been used to control mould growth during red sorghum malting. The use of this biocontrol in steeping liquor has been optimized with some success and the combined use of a 0.2% NaOH steep, followed by a re‐steep in a B. subtilis‐based biocontrol, has been proposed. The sharpness and variability of the β‐amylase peak and the higher levels of β‐glucanase, obtained in the presence of B. subtilis cells, were highlighted. In this work, the suitability of the Weibull four‐parameters model to predict sorghum malt α‐amylase activity during the enzyme induction stage of red sorghum germination has been compared with that of a second order polynomial model and a general linear model. Results obtained showed that the Weibull four‐parameters model could be used to predict α‐amylase activity, with significant goodness of fit when compared with the second order polynomial model and the general linear model. The effects of steeping treatment (combined use of 0.2% NaOH and B. subtilis‐S499 starters) and the germination temperature are presented. When the B. subtilis culture used as a starter was diluted, the treatment efficacy to develop α‐amylase activity was lost. This study also showed that the germination temperature affected the α‐amylase activity rate increase during the induction phase. Copyright © 2013 The Institute of Brewing & Distilling  相似文献   

4.
A preliminary study of malting conditions for six Thai rice cultivars was conducted. Three non‐glutinous rice cultivars (KDML105, PT60, and WR) and three glutinous rice cultivars (SPT, RD6, and KND) were selected. The steeping durations (24, 48, and 72 h) and temperatures (20, 25 and 30°C) were investigated for their effect on α‐ and β‐amylase, the key enzymes for malt quality evaluation. During steeping, the production of both enzymes was lower than at the germination process. The longer the steeping duration, the lower the maximum β‐amylase activity obtained. The contradictory effect was observed for α‐amylase activity, near the end of the germination time. Additionally, temperature influenced the water absorption content as well as the amylolytic enzyme activity. Particularly at 30°C, the maximum β‐amylase activity (6.7 unit/mg protein) was found in KND malt steeped for 24 h, and maximum α‐amylase activity (20 unit/mg protein) was found in PT60 malt steeped for 72 h. The amount of enzyme production depended on the variety rather than the amylose content in the rice. The optimal condition for malting rice regarding β‐amylase activity and α‐amylase activity was analyzed at 30°C, with steeping for 24 h and germination for 4–5 days.  相似文献   

5.
Previous work has shown that Bacillus subtilis‐S499‐based biocontrol treatments applied without aeration at the steeping stage of red sorghum malting offer good mould reduction, but yield malts with low levels of key hydrolytic enzymes. Thus we attempted to raise these levels by aerating the steeping liquor, varying the steeping time (from 8 to 40 h) and temperature (from 25 to 35 °C), and combining a biocontrol treatment with prior steeping in 0.2% NaOH. Aeration proved particularly important whenever B. subtilis cells were present in the steep liquor. The optimal temperatures for α‐ and β‐amylase were 30 and 25 °C, respectively. By increasing the steeping time, it was possible to improve the α‐amylase activity, but the β‐amylase activity peaked sharply between 16 and 20 h, depending on the steeping medium. A good compromise was steeping in a biocontrol medium for 14–16 h at 30 °C. Combination steeping treatments (0.2% NaOH for 8 h followed by biocontrol for 8 h) yielded malts of a quality approaching that afforded by dilute alkaline treatment. Copyright © 2012 The Institute of Brewing & Distilling  相似文献   

6.
Three phytosterols were isolated from Musa spp. flowers for evaluating their capabilities in inhibiting glucosidase and amylase activities and glycation of protein and sugar. The three phytosterols were identified as β‐sitosterol (PS1), 31‐norcyclolaudenone (PS2) and (24R)‐4α, 14α, 4‐trimethyl‐5α‐cholesta‐8, 25(27)‐dien‐3β‐ol (PS3). IC50 values (the concentration of inhibiting 50% of enzyme activity) of PS1, PS2 and PS3 against α‐glucosidase were 283.67, 11.33 and 43.10 μg mL?1, respectively. For inhibition of α‐amylase, the IC50 values of PS1, PS2 and PS3 were 52.55, 76.25 and 532.02 μg mL?1, respectively. PS1 was an uncompetitive inhibitor against α‐amylase with Km at 5.51 μg mL?1, while PS2 and PS3 exhibited a mixed‐type inhibition with Km at 52.36 and 2.49 μg mL?1, respectively. PS1 and PS2 also significantly inhibited the formation of advanced glycation end products (AGEs) in a BSA–fructose model. The results suggest that banana flower could possess the capability in prevention of the diseases associated with abnormal blood sugar and AGEs levels, such as diabetes.  相似文献   

7.
The Plackett‐Burman multifactorial design was employed to screen the important malting parameters for superoxide dismutase (SOD) in final malt of Ganpi‐3. The eight factors screened for SOD were steeping temperature, steeping time, peroxide hydrogen concentration in steeping water, germination temperature, germination time, withering temperature, drying temperature and kilning temperature. Variance analysis showed that steeping time, germination temperature and kilning temperature were significant for SOD activity. Box‐Behnken experimental design was further used to optimize the levels of the above three factors. By response surface methodology and canonical analysis, the optimal malting factors for higher SOD activity in final malt were: steeping time 42.2 h, germination temperature 16.9°C and kilning temperature 82.9°C. Under these conditions, the model predicted a SOD activity of 2234 U/g of dry weight malt. Verification of the optimization showed that a SOD activity of 2220 U/g was observed under optimal conditions. It showed that the experimental data could be reliably predicted by the polynomial model. Besides Ganpi‐3, three other barley varieties including Ganpi‐4, Ken‐2 and Hamelin were malted under optimal and common conditions under laboratory conditions. To some extent, SOD activities were higher in malts from the optimal malting process than those from the common malting process. Especially, SOD activities in Ganpi‐3 and Hamelin increased by 18.8% and 15.3%, respectively. Furthermore, twenty‐nine samples of malts, including eleven imported malts and eighteen domestic malts, were used. Relationships between SOD activity in malt and the reducing power of wort were examined. There was significant correlation between SOD activity and the reducing power of wort (R2 = 0.8069).  相似文献   

8.
Pito is a traditional fermented beverage produced from malted sorghum or millet grains. Steeping is usually performed at 30°C. Limited information exists on the effect of temperature on the characteristics of the malted grains and the Pito. The aim of this work was to study the effect of varying the steeping temperature (30, 35 or 40°C) on the quality of malt and of the Pito brewed from Kadaga sorghum and to specifically determine the diastatic power, extract yield and attenuation limit of the malt. Total soluble solids, pH and alcohol content, as well as the sensory evaluation of the Pito brewed at both 40 and 30°C were assessed. Results from analysis showed that the 40°C malts had the highest diastatic power (88.1 SDU/g), extract yield (96.75% d.m.) and attenuation limit (78.95%). Pito produced from malt steeped at 40°C yielded a significantly higher alcohol content of 3.54 g/100 g, a total soluble solids of 4.34 and a pH of 3.57 and this Pito was preferred over the traditionally prepared Pito at the steeping temperature of 30°C. Therefore steeping sorghum at 40°C yields a quality malt and a quality Pito. This study should aid in the adoption of sorghum for brewing purposes. Copyright © 2015 The Institute of Brewing & Distilling  相似文献   

9.
Rhizopus microsporus, recently isolated from a solid culture of Heng‐Shui Lao‐Bai‐Gan (HSLBG, a famous distilled liquor in Northern China) was found to produce a novel extracellular acid stable and thermostable α‐amylase. This fungal α‐amylase was purified using ammonium precipitation, Sephadex G‐25 desalination and DEAE‐52 cellulose chromatography. Its molecular weight was estimated to be 75 kDa by SDS–PAGE. The optimum pH and temperature of this enzyme was pH 5.0 and 70°C respectively. Thermostability and kinetic analysis through the Arrhenius and Michaelis–Menten equations revealed that this enzyme showed an exceptional activity at low pH and high temperature. A combination of this thermostability and acid stability could be a valuable trait for the efficient hydrolysis of amylose to glucose in large‐scale biotechnology applications. Copyright © 2012 The Institute of Brewing & Distilling  相似文献   

10.
The low β‐amylase activity of sorghum malt is a major concern when malts are intended for use in brewing. Several studies have shown that the germination temperature plays an important role in β‐amylase synthesis. In this study, the cold shock treatment was envisioned as a means of improving β‐amylase synthesis during red sorghum malting. The results show that, when a high‐frequency decrease in the germination temperature is used, the obtained malt exhibits a significantly increased β‐amylase activity. This study shows that this increase is not sufficient to consider cold shock as a means of improving β‐amylase activity for red sorghum brewing use, as the processabilty of the malts is unsatisfactory. Copyright © 2015 The Institute of Brewing & Distilling  相似文献   

11.
Pito is an alcoholic beverage obtained through a yeast (Saccharomyces cerevisiae) fermentation of wort extracted from sorghum (Sorghum bicolor L. Moench) malt. The malting conditions of sorghum are thought to influence the quality characteristics of the malt, and subsequently the quality of the pito obtained from it. Studies were carried out on a local sorghum cultivar grown in Ghana – chireh, to optimize the conditions for malting conditions for pito production in Ghana. A 33 full factorial experimental design was replicated with steeping times of 12, 16 and 22 h, germination times of 3, 4 and 5 days, and malt drying temperatures of 30, 40 and 50 °C as factors. Diastatic power, extract yield, attenuation limit and free amino nitrogen were determined. Germination duration significantly affected diastatic power and free amino nitrogen (p < 0.001). Extract yield was also significantly influenced by germination duration (p = 0.001). The germination time, steeping time and drying temperature had no significant effect on the attenuation limit. The optimal conditions for malting this specific cultivar grown in Ghana to obtain critical malt quality indices are 12.0–12.5 h steeping, 5 days of germination at 30 °C and drying at 40 °C. Free amino nitrogen levels in all treatments were higher than the minimum requirement for good yeast nutrition and fermentation. Copyright © 2015 The Institute of Brewing & Distilling  相似文献   

12.
The in vitro inhibitory activities of different seed extracts prepared from cranberry bean mutant SA‐05 and its wild‐type variety Hwachia against aldose reductase, α‐glucosidase and α‐amylase were examined. The results indicated that the polyphenolics‐rich extracts obtained using 800 g kg?1 methanol and 500 g kg?1 ethanol demonstrated inhibitory activities against aldose reductase (IC50 of 0.36–0.46 mg mL?1) and α‐glucosidase (IC50 of 1.32–1.94 mg mL?1). The 500 g kg?1 ethanol extracts also showed α‐amylase inhibitory activities (IC50 of 70.11–80.22 μg mL?1). Subsequent extracts, prepared further with NaCl and H2O from precipitates of 800 g kg?1 methanol or 500 g kg?1 ethanol extracts, exhibited potent α‐amylase inhibitory activities (IC50 of 17.68–38.68 μg mL?1). A combination of 500 g kg?1 ethanol extraction plus a subsequent H2O extraction produced highest polyphenolics and α‐amylase inhibitors. The SA‐05 α‐amylase inhibitor extracts showed greater inhibitory activities than that of Hwachia. Thus, cranberry bean mutant SA‐05 is an advantageous choice for producing anti‐hyperglycaemic compounds.  相似文献   

13.
A protease from sorghum malt variety KSV8–11 was purified by a combination of dialysis against 4 M sucrose, ion‐exchange chromatography on Q‐Sepharose (Fast flow), gel filtration chromatography on Sephadex G‐100 and hydrophobic interaction chromatography on Phenyl Sepharose CL‐4B. The enzyme was purified 5‐fold to give a 14.1% yield relative to the total activity in the crude extract and a final specific activity of 1348.9 U mg?1 protein. SDS‐PAGE revealed a single migrating protein band corresponding to a relative molecular mass of 16 KDa. Using casein as substrate, the purified protease had optimal activity at 50°C and maximal temperature stability between 30°C and 40°C but retained over 64% of its original activity after incubation at 60°C for 30 min. The pH optimum was 5.0 with maximum stability at pH 6.0 but 60% of the activity remained after 24 h between pH 5.0 and 8.0. The protease was inhibited by Ag+, Ca2+, Co2+, Fe2+, Mg2+, iodoacetic acid (IAA) and p‐chloromercuribenzoate (p‐CMB), stimulated by Cu2+, Sr2+, phenylmethylsulfonyl‐fluoride (PMSF) and 2‐mercaptoethanol (2‐ME) while Mn2+ and ethylenediaminetetraacetic acid (EDTA) had no effect. The purified enzyme had a Km of 18 mg·mL?1 and a Vmax of 11.1 μmol · mL?1 · min?1 with casein as substrate.  相似文献   

14.
Arabinoxylans (AXs) from wheat malts potentially affect beer quality and production. β‐ d ‐Xylosidase is a key enzyme that degrades the main chains of AXs to produce xylose. This study performed a partial characterization of β‐ d ‐xylosidase from wheat malts. The optimal temperature was 70 °C and the enzyme exhibited excellent thermostability, that is, residual activities were 92.6% at 60 °C for 1 h. The enzyme was stable over a pH range of 3.0–6.0 and showed optimum activity at pH 3.5 and 4.5. Kinetic parameters Km and Vmax of wheat malt β‐ d ‐xylosidase against p‐nitrophenyl‐xyloside were 1.74 mmol L−1 and 0.76 m m min−1, respectively. The enzyme activity was severely inhibited by Cu2+, moderately inhibited by Mn2+, Mg2+, Al3+, Ca2+, Ba2+ and Na+ and mildly inhibited by Fe3+ and Fe2+. The partial enzymatic characterization achieved in this study can be used as a theoretical basis for purifying β‐ d ‐xylosidase from wheat malts. Copyright © 2015 The Institute of Brewing & Distilling  相似文献   

15.
A new amylolytic enzyme found in barley (Hordeum vulgare) grain was partially characterised with respect to physicochemical properties and enzymatic activity. The enzyme preparation showed one antigenically homogeneous amylolytic band. Isoelectric focusing resolved the new amylase into two components, one isoelectric at pH 4.5, the other at pH 3.0. During focusing the original activity of the new amylase decreased by 80%. The purified preparation was inactivated by pH-values below 4.5 and above 9.0 and also by temperatures above + 40°C for 1 h. The new amylase splits the 1,4-α-glycosidic linkages, clearly by endo-attack, of starch, amylopectin, amylose and β-limit dextrin optimally at pH 6.5 at +40°C giving Km-values 8.9 × 10?3, 4.4 × 10?3, 6.6 × 10?3 and 1.7 × 10?3 g/ml, respectively. The hydrolysis products from β-limit dextrin were 24% glucose and 46% maltose in the total digest. Mercuric chloride, pCMB,a EDTAa and TRISa have no noticeable effect on the new amylase, indicating that it is stable under conditions where the other amylolytic enzymes are deactivated. The new amylase seems to be a hydrolase acting on o-glycosyl compounds, EC 3.2.1., but could not be identified with any of the amylolytic enzymes of vegetable origin studied previously.  相似文献   

16.
Two black rice varieties, “black non‐waxy” and “black waxy”, were investigated as possible raw materials for the production of malt. The malting conditions were optimised using response surface methodology. The three process parameters were steeping, germination time and temperature. Each parameter was tested at three levels: adjustment degrees of steeping were 38, 41, and 44%, germination times were 6, 7, and 8 days, and the temperatures were 20, 25 and 30°C. At the end of the germination process, all samples were kilned at 50°C for 24 h, and shoot/rootlets were removed before a detailed quality assessment was performed. Data analysis was performed using the Design Expert Statistic Program. The optimal conditions found for both rice varieties were as follows: germination time of 8 days at 30°C and 44% grain moisture. Although the extract yield, and a‐amylase and β‐amylase activities of both rice malts were lower than barley malt, the higher activity of limit‐dextrinase enzyme and apparent attenuation limit (AAL), which was higher than 80%, suggests that rice malt has potential for use in brewing.  相似文献   

17.
The effect of different substances potentially inhibitory of ruminal amylase activity in sheep was assessed using biochemical and electrophoretic assays. Most amylase activity was detected in the particle‐associated fraction (70%) of the ruminal contents (which was selected for the assays) in comparison with the bacterial (21%) and extracellular (9%) fractions. Salts of divalent ions such as Sn2+, Hg2+, Cu2+ and Zn2+ produced 90, 82, 65 and 44% inhibition of amylase activity respectively when assayed at a relative concentration of 5 × 10?3 mol l?1. Organic acids such as tannic, formic, ascorbic and benzoic acid produced 79, 48, 43 and 37% inhibition respectively, whereas chelators such as EDTA, EGTA and 1,10‐phenanthroline produced an inhibition ranging from 32 to 37%. Substrate SDS‐PAGE zymograms allowed the identification of different amylase‐active bands in ruminal extracts, showing a wide range of relative molecular masses (from 36 to more than 100 kDa). Such zymograms also confirmed the effect of some inhibitors. The reversibility of the inhibitory effect of some of the assayed substances was assessed. ZnSO4 was the most persistent inhibitory substance even at low concentrations and, owing to its low toxicity, appears to be an adequate substance to reduce the high in vitro ruminal degradation of starch. Implications for the process of enzymatic digestion of starch are discussed. © 2002 Society of Chemical Industry  相似文献   

18.
Sorghum malt α-glucosidase activity was highest at pH 3.75 while that of barley malt was highest at pH 4.6. At pH 5.4 employed in mashing sorghum malt α-glucosidase was more active than the corresponding enzyme of barley malt. α-Glucosidase was partly extracted in water but was readily extracted when L-cysteine was included in the extraction buffer, pH 8. Sorghum malt made at 30°C had higher α-glucosidase activities than the corresponding malts made at 20°C and 25°C. Nevertheless, the sorghum malts made at 20°C and 25°C produced worts which contained more glucose than worts of malt made at 30°C. Although barley malts contained more α-glucosidase activity than sorghum malts, the worts of barley had the lowest levels of glucose. The limitation to maltose production in sorghum worts, produced at 65°C, is due to inadequate gelatinization of starch and not to limitation to β-amylase and α-amylase activities. Gelatinization of the starch granules of sorghum malt in the decantation mashing procedure resulted in the production of sorghum worts which contained high levels of maltose, especially when sorghum malt was produced at 30°C. Although the β-amylase and α-amylase levels of barley malt was significantly higher than those of sorghum malted optimally at 30°C, sorghum worts contained higher levels of glucose and equivalent levels of maltose to those of barley malt. It would appear that the individual activities of α-glucosidase, α-amylase and β-amylase of sorghum malts or barley malts do not correlate with the sugar profile of the corresponding worts. In consequence, specifications for enzymes such as α-amylase and β-amylase in malt is best set at a range of values rather than as single values.  相似文献   

19.
BACKGROUND: Diabetes mellitus (DM) is a chronic metabolic disorder characterized by defects in insulin secretion and action, which can lead to damaged blood vessels and nerves. With respect to effective therapeutic approaches to treatment of DM, much effort has being made to investigate potential inhibitors against α‐glucosidase and α‐amylase from natural products. The edible marine brown alga Ecklonia cava has been reported to possess various interesting bioactivities, which are studied here. RESULTS: In this study, five phloroglucinal derivatives were isolated from Ecklonia cava: fucodiphloroethol G ( 1 ), dieckol ( 2 ), 6,6′‐bieckol ( 3 ), 7‐phloroeckol ( 4 ) and phlorofucofuroeckol A ( 5 ); compounds 1, 3 and 4 were obtained from this genus for the first time and with higher yield. The structural elucidation of these derivatives was completely assigned by comprehensive analysis of nuclear magnetic spectral data. The anti‐diabetic activities of these derivatives were also assessed using an enzymatic inhibitory assay against rat intestinal α‐glucosidase and porcine pancreatic α‐amylase. Most of these phlorotannins showed significant inhibitory activities in a dose‐dependent manner, responding to both enzymes, especially compound 2 , with the lowest IC50 values at 10.8 µmol L?1 (α‐glucosidase) and 124.9 µmol L?1 (α‐amylase), respectively. Further study of compound 2 revealed a non‐competitive inhibitory activity against α‐glucosidase using Lineweaver‐Burk plots. CONCLUSION: These results suggested that Ecklonia cava can be used for nutritious, nutraceutical and functional foods in diabetes as well as for related symptoms. Copyright © 2009 Society of Chemical Industry  相似文献   

20.
Ascorbic acid (AA) degradation and colour changes, measured by the lightness index (L*), were determined in cashew apples (at low dissolved O2 concentrations) heated at high temperature (100–180 °C) in a hermetically sealed cell. A nonisothermal method was developed to estimate thermal degradation kinetics. The results showed that reaction kinetics during heat treatments were well represented by first‐order reactions. The temperature dependence of the kinetic constants was described by an Arrhenius type equation. The activation energy (Ea) for AA degradation and lightness index were 94 ± 3 and 98 ± 3 kJ mol?1, respectively. The reaction rate constant at 140 °C for AA degradation (64 × 10?5 ± 3 × 10?5 s?1) was twice that for the lightness index change (33 × 10?5 ± 2 × 10?5 s?1). Results allow generating temperature profiles of heat processes that would help preserve the AA of cashew apples as well as control the colour formation during high‐temperature processes.  相似文献   

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