Starch Lipids of Barley and Malt

Barley and malt starches were compared with respect to their lipid content and composition. The starch lipids were first fractionated into internal and surface lipid fractions followed by lipid class and fatty acid analyses of each fraction. Barley starch contained 13 mg/g lipids, of which 9.3 mg were internal lipids and 3.7 mg were surface lipids. The total lipid content of malt starches varied between 11 and 13 mg/g of starch. However, malt starch contained only 1 mg of surface lipids; therefore, the internal lipid contents were as high as or even higher than those in the corresponding fraction of barley starch. Lipid class analyses suggested that the ability for hydrolysis of starch surface lipids was increased in malt. The hydrolysis occurred during the malting or the isolation process, resulting in reduced surface lipid content in malt starch. However, no reduction in the portion of polyunsaturated fatty acids was seen; therefore, lipid oxidation could not have been responsible for the lower content of malt starch surface lipids. Also, not only was the content of starch internal lipids higher in malt, but the composition of these lipids was different when compared to barley starch. The increase in starch internal lipids during malting may be due to transportation and reacylation of free fatty acids that had been liberated by hydrolysis from surface lipids.     

Fragmentation of Waxy Rice Starch Granules by Enzymatic Hydrolysis

Small starch particles were prepared by hydrolyzing waxy rice starch using α‐amylase and then ultrasonicating in ethanol. Differential scanning calorimetry (DSC) revealed that a mild hydrolysis for 3 hr increased the melting enthalpy of the starch, which might indicate that the hydrolysis was selective in the amorphous regions. Later, at 6–24 hr, the hydrolysis rate was reduced, with gradual decreases in DSC melting enthalpy, indicating that the crystalline regions were eroded simultaneously. X‐ray diffraction patterns revealed the same trend as the DSC results. Average diameter of starch granules or particles was decreased dramatically in both volume‐ and number‐based measurements (5.94→1.64 μm, and 0.45→0.18 μm, respectively) during the early stage of rapid hydrolysis (up to 3 hr). Native waxy rice starch exhibited a particle size distribution with a major peak at 5.6 μm. After hydrolysis for 3 hr, the volume distribution of starch granules changed to two major size peaks at 0.5 and 3.6 μm. The starch fragment of 0.5 μm was assumed to consist of crystalline blocklets. With excessive hydrolysis (24 hr) or ultrasonication, however, starch particle diameter was increased, indicating that the particles might be swollen or aggregated into clusters.     

Enzymatic and Acidic Hydrolysis of Cationized Waxy Maize Starch Granules

A series of wet‐cationized starch granules from waxy maize with different degrees of substitution (DS) were solubilized with either 2.2M HCl (lintnerization) or with the α‐amylase of Bacillus amyloliquefaciens. The maximum rate of the enzymatic hydrolysis occurred in starches with intermediate DS. It appeared that the cationic substituents interfered with the binding to the active site of the enzyme at high levels of substitution. The DS remained fairly constant in the granular residues after the enzymatic attack. The rate of the acidic hydrolysis increased with increasing DS but the final level of solubilization slightly decreased. The DS of the residual starch material decreased to 40% of the original level, showing that a large part of the cationic groups was found within the amorphous parts of the granules. A dry‐cationized sample with a high DS was also treated with the acid and lost a major part of its substituents at low levels of lintnerization. Probably most of the substituents were associated with the surface and channels of these granules. The cationized starches possessed branches that were resistant to isoamylase attack and the samples also contained β‐amylolysis resistant dextrins. The proportion of resistant dextrins in the granular residues decreased after lintnerization, but remained constant after the enzymatic hydrolysis.     

小黄鱼边角料的酶解工艺及酶解液性能研究

为开发利用小黄鱼边角料制备浓缩鱼汤,本研究采用酶解工艺对小黄鱼边角料进行酶解并对其酶解液的功能活性进行研究。以氨基酸态氮含量为指标,通过单因素及响应面试验探究酶制剂种类及添加量、pH值和酶解时间对酶解效率的影响;采用DEAE层析柱对酶解液进行分离纯化,SDS-PAGE凝胶电泳测定酶解多肽的分子量;通过测定酶解多肽对·OH和DPPH自由基的清除率、对细菌生长曲线的影响判断酶解多肽的抗氧化性和抗菌性。结果表明,以碱性蛋白酶为酶制剂,当酶与底物蛋白比为322 U·g^-1、固液比(m∶v)为1∶2、pH值为11.0、温度为55℃、酶解时间为2 h时,小黄鱼酶解液中氨基酸态氮含量为0.545 2 g·100g^-1;酶解液经DEAE柱分离得到了Ⅰ、Ⅱ、Ⅲ、Ⅳ四组多肽,其中组分Ⅲ多肽的分子量小于3.3 kDa;当酶解液中氨基酸态氮含量分别为8.62和25.59 mg·mL^-1时,对·OH和DPPH自由基的清除率分别约为80%和61%;组分Ⅲ多肽对枯草芽孢杆菌、酵母菌、金黄色葡萄球菌、大肠杆菌均有不同程度的生长抑制作用。本研究为小黄鱼边...     

鼠李糖脂二糖脂强化酶解木质纤维素

将经过纯化的鼠李糖脂二糖脂添加于纤维素酶酶水解试验中,以稻草、竹叶为底物,分析水解过程中纤维素酶酶活（以FPA计）及还原糖浓度的变化特征,探讨和分析鼠李糖脂二糖脂对稻草和竹叶中木质纤维素水解产还原糖能力、纤维素酶活的稳定性、发酵液表面张力和pH值的影响作用。结果表明,添加鼠李糖脂二糖脂对木质纤维素类底物酶水解过程中还原糖浓度的增加、酶活稳定性的提高有明显的促进作用,并且其促进作用随着表面活性剂添加量的适量增加而增强,当添加量为0．24％时,稻草和竹叶还原糖的产量分别提高了17．19％和27．68％。此外,水解反应结束后,加入鼠李糖脂二糖脂的水解液表面张力值显著降低,且随着添加量的增高而降低,当添加量为0．24％时,可分别降至63．4和60．8mN·m^-1左右,而pH值的变化微小。     

Pretreatment and Enzymatic Hydrolysis of Sorghum Bran

Sorghum bran has potential to serve as a low‐cost feedstock for production of fuel ethanol. Sorghum bran from a decortication process (10%) was used for this study. The approximate chemical composition of sorghum bran was 30% starch, 18% hemicellulose, 11% cellulose, 11% protein, 10% crude fat, and 3% ash. The objective of this research was to evaluate the effectiveness of selected pretreatment methods such as hot water, starch degradation, dilute acid hydrolysis, and combination of those methods on enzymatic hydrolysis of sorghum bran. Methods for pretreatment and enzymatic hydrolysis of sorghum bran involved hot water treatment (10% solid, w/v) at 130°C for 20 min, acid hydrolysis (H₂SO₄), starch degradation, and enzymatic hydrolysis (60 hr, 50°C, 0.9%, v/v) with commercial cellulase and hemicellulose enzymes. Total sugar yield by using enzymatic hydrolysis alone was 9%, obtained from 60 hr of enzyme hydrolysis. Hot water treatment facilitated and increased access of the enzymes to hemicellulose and cellulose, improving total sugar yield up to 34%. Using a combination of starch degradation, optimum hot water treatment, and optimum enzymatic hydrolysis resulted in maximum total sugar yield of up to 75%.     

Physicochemical Properties of Zero Amylose Hull-less Barley Starch

Zero amylose starch isolated from hull-less barley (HB) showed a typical A-type diffraction pattern. The X-ray analysis suggested that granules of zero amylose (SB94794) and 5% amylose (CDC Candle) HB starches had lower crystallinity than did commercial waxy corn starch. Differential scanning calorimetry showed lower transition temperatures and endothermal enthalpies for the HB starches than for the waxy corn starch. The zero amylose HB starch showed a Brabender pasting curve similar to that of waxy corn starch, but with lower pasting and peak temperatures and a higher peak viscosity. Noteworthy characteristics of zero amylose HB starch were its low pasting temperature and high paste clarity and freezethaw stability, which make this starch useful for many food and industrial applications.     

Differences in Starch Granule Composition and Structure Influence In Vitro Enzymatic Hydrolysis of Grain Meal and Extracted Starch in Two Classes of Canadian Wheat (Triticum aestivum L.)

Starch granule composition and amylopectin structure affect starch digestibility, an important factor influencing wheat grain utilization for human food consumption. Six bread wheat cultivars with four belonging to the Canada Western Red Spring (CWRS) and two Canada Prairie Spring Red (CPSR) market classes were analyzed for the relationship between their grain constituents and in vitro enzymatic hydrolysis of starch. CPSR cultivars had higher starch and amylose concentrations compared with CWRS cultivars, which had a higher protein concentration. Starch granule size distribution did not differ among the genotypes, except AC Foremost, which had significantly (P < 0.05) higher volume percent of B‐type starch granules (≈15%) and lower volume percent of A‐type starch granules (≈9%) compared with other cultivars. Fluorophore‐assisted capillary electrophoresis revealed a lower content of R‐IV (DP 15–18, ≈6%) and a higher content of R‐VII (DP 37–45, ≈7%) chains in the CPSR cultivars compared with the CWRS cultivars. Starch in vitro enzymatic hydrolysis showed that compared with CWRS cultivars, the two CPSR cultivars had reduced amounts of readily digestible starch and higher amounts of slowly digestible starch and resistant starch. Consequently, the two CPSR cultivars also showed lower hydrolysis indexes in grain meal as well as extracted starch. CPSR cultivars, with higher starch and amylose concentrations, as well as a higher content of long chains of amylopectin, showed a reduced starch in vitro enzymatic hydrolysis rate.     

Characterization of Maize Starch Nanoparticles Prepared by Acid Hydrolysis

Starch nanoparticles (SNP) from maize starches of varying amylose content (0–71%) were prepared by acid hydrolysis (3.16M H₂SO_4, at 40°C up to 6 days) followed by repeated water washings. During the washing cycles, nonwaxy starches (normal, Hylon V, and Hylon VII) had suspended particles in the water washings, which were not evident in waxy starch. Microscopic examination revealed the presence of SNP in the “cloudy supernatants” of nonwaxy starches and in the “final washed residue” of waxy maize. The objective of this study was to collect SNP fractions accordingly and determine whether variation in the native starch amylose content would influence the yield, morphology, and crystallinity of the SNP. In nonwaxy starches, the yield of SNP increased up to 26.6% with hydrolysis time and was proportional to the amylose content. Morphology of SNP differed with starch type: flat/elliptical (500 nm) in waxy, oval/irregular (50–200 nm) in normal, oval/round (40–50 nm) in Hylon V, and square/polygonal (50–100 nm) in Hylon VII. X‐ray diffraction confirmed the presence of A‐type crystals in SNP from all starch types and a crystalline transformation from B‐ to A‐type in Hylon starches. The relative crystallinity of SNP was higher than their native starch counterparts.     

Composition of Functional Lipids in Hulled and Hulless Barley in Fractions Obtained by Scarification and in Barley Oil

Two cultivars of hulled barley (Thoroughbred and Nomini) and two cultivars of hulless barley (Doyce and Merlin) were scarified to abrade the outer layers of hull and pericarp. The resulting scarification fines fractions were evaluated as potential sources of functional lipids (phyto‐sterols, tocopherols, and tocotrienols). The levels of total phytosterols and total tocotrienols in the barley scarification fine fractions were probably not high enough to justify their use as functional foods. However, the levels of total phytosterols and total tocotrienols in the oils extracted from both whole kernels and scarified fines were both sufficiently high to make it reasonable to consider their potential use as new functional oils. Indeed, the levels of total tocotrienols in barley oils (2,911–6,126 mg/kg of oil) are several‐fold higher than those reported in two other oils that are being marketed as high in tocotrienols: palm oil (530 mg/kg) and rice bran oil (770 mg/kg). The levels of total phytosterols in barley oils range from 1.20 to 9.60 g/100 g of oil.     

Structural Changes of Starch Molecules in Barley Grains During Germination

The germination of barley grains is an important step in malt production for beer brewing. This study examines the changes in starch molecular structure in barley grains under optimal conditions for sprouting. Two barley varieties were tested: Schooner and Grimmett, which are low and moderate dormancy grains, with >90 and <5% of grains germinating within two days in sprouting conditions, respectively. The barley grains were germinated in humid conditions after being soaked in excess water for 24 h. The grain weight and starch content of Schooner decreased significantly (P < 0.05) with germination time, whereas those of Grimmett showed no significant changes (P > 0.05). The starch chain‐length distributions, analyzed from enzymatically debranched starch molecules with size‐exclusion chromatography, indicated that the shorter amylopectin branches of Schooner were degraded at a faster rate than its longer amylopectin branches, which was also confirmed by the decreasing degree of branching with germination time. The changes in starch molecular structure of Grimmett grains were less apparent. The results of this study showed that barley grains containing shorter starch chains can produce sugars more quickly, which indicates that starch structure can serve as one of the specifications when selecting barley grains for brewing.     

Release of Bound Lipids in Cereal Starches Upon Hydrolysis by Glucoamylase

The raw starch granules from corn, rice, and wheat were hydrolyzed by practically pure glucoamylase (Rhizopus niveus). The bound lipids remaining in the residual starches were investigated, of which the major components of the lipids, free fatty acids (FFA) in corn starch, FFA and phospholipids (PL) in rice starch, and PL in wheat starch were determined. In each case, the bound FFA and PL were decreased to some extent during the initial stage of hydrolysis. During the later stages, the FFA continued to gradually decrease, while the level of PL stabilized. It was interesting that some of the bound lipids were released from the granules upon glucoamylase hydrolysis, differing from the model amylose-lipid complexes. Furthermore, the structures of the residual starches were investigated. The blue value and λ_max of the starches were increased by partial hydrolysis of the starch granules using practically pure glucoamylase. Two gel-permeation chromatography analyses revealed that the relative amount of amylose fraction was increased by glucoamylase hydrolysis, and also that the increments were reduced by the defatting of bound lipids. The results suggest that the increase in amylose fraction is attributable to the existence of bound lipids in the granules.     

α-Amylolysis of Large Barley Starch Granules

The α-amylolysis of large (volume average 16 μm) barley starch granules was studied by measuring the amount of carbohydrates solubilizing during hydrolysis, and the changes in morphology and molecular structure of the granule residues by scanning electron microscopy, particlesize analysis, size-exclusion chromatography, X-ray diffraction, and differential scanning calorimetry. X-ray diffraction showed that, in the earlier stages of α-amylolysis, both amorphous and crystalline parts of the granules were equally solubilized. More extensive hydrolysis caused a gradual decrease in A-type crystallinity and degradation of the granular structure. Scanning electron microscopy revealed that hydrolysis proceeded through pinholes, and pitted and partially hollow granule residues were formed. The lipid-complexed amylose was less susceptible to α-amylolysis than free amylose and amylopectin. Lipid-complexed amylose started leaching out of the granule residues only after half of the starch had solubilized due to the α-amylase treatment. Even though scanning electron microscopy indicated that there were intact granules left throughout the hydrolysis, the results obtained suggested that α-amylolysis of large barley starch granules proceeded rather evenly among the granules.     

Resistant Starch Content Is Related to Granule Size in Barley

Physical properties of resistant starch (RS) were examined in a range of barley genotypes to determine the contribution of starch and seed physical characteristics to the RS component. Thirty‐three barley genotypes were studied, which varied significantly in their RS, amylose, and starch contents and grain yield. From 33 genotypes, 13 exhibiting high RS were selected for detailed physicochemical analysis of starch. In high‐RS varieties, granule size and number were unimodal, compared with normal starches from a reference genotype, which showed a bimodal distribution. Principal component analysis (PCA) showed that a higher content of granules <15 µm was positively correlated with RS and amylose content, whereas the proportion of granules 15–45 µm was negatively correlated with the RS and amylose contents. Physical fractionation of starches by centrifugation into different population sizes demonstrated that size alone is not an accurate indicator of the population of A‐type and B‐type granules within a given genotype. PCA also showed that large 15–45 µm granules were positively correlated with seed thickness and that thousand grain weight was positively correlated with seed width. High‐RS and high‐amylose genotypes showed variation in overall yield and starch content, with some genotypes showing yield comparable to the reference genotype. Analysis of amylopectin chain length distribution showed that high amylose or RS content was not associated with a higher proportion of amylopectin long chains when compared with either waxy or reference (normal) barley genotypes. This study highlights useful markers for screening barley genotypes with favorable starch characteristics.     

Starch and By‐Products from a Laboratory‐Scale Barley Starch Isolation Procedure

Starch was isolated from three different barleys with normal, highamylose, or high‐amylopectin (waxy) starch. The laboratory‐scale starch isolation procedure included crushing of grains, steeping, wet milling, and sequential filtration and washing with water and alkali, respectively. Yield and content of starch, protein, and dietary fiber, including β‐glucan, were analyzed in isolated starch and in the by‐products obtained. Starch yield was 25–34%, and this fraction contained 96% starch, 0.2–0.3% protein, and 0.1% ash. Most of the remaining starch was found in the coarse material removed by filtration after wet milling, especially for the high‐amylose barley, and in the starch tailings. Microscopy studies showed that isolated starch contained mostly A‐granules and the starch tailings contained mostly B‐granules. Protein concentration was highest in the alkali‐soluble fraction (54%), whereas dietary fiber concentration was highest in the material removed by filtration after alkali treatment for the normal and waxy barleys (55%). The β‐glucan content was especially high for the waxy barley in this fraction (26%). The study thus showed that it was possible to enrich chemical constituents in the by‐products but that there were large differences between barleys. This result indicates a need for modifications in the isolation procedures for different barleys to obtain high yields of starch and different by‐products. Valuable by‐products enriched in β‐glucan or protein, for example, may render starch production more profitable.     

几种化学物质对稻草秸秆酶解糖化的影响

在木质纤维素酶解研究领域,高浓度还原糖的获得是实现其能源转化的基础。以稀硫酸预处理后的稻草秸秆为原料,初始酶解物料条件为20%（重量/体积）,木聚糖酶220U.g-（1底物）,纤维素酶6FPU.g-（1底物）,果胶酶50U.g-（1底物）,选取吐温80（Tween80）、MgSO4、FeSO4、聚乙二醇（PEG）和牛血清白蛋白（BSA）作为酶解体系添加物,分别考察了其添加量对还原糖浓度的影响。试验结果表明：在稻草秸秆酶解体系中,Tween80、MgSO4、FeSO4、PEG和BSA5种化学物质各自最佳添加量分别为0.05、0.0005、0.02、0.01g和0.0005g.g-（1底物）;助催化作用强度依次为MgSO4〉Tween80〉BSA〉FeSO4〉PEG。添加MgSO40.0005g.g-（1底物）,48h糖化后,还原糖浓度达到72.45g.L-1,比对照提高了7.98%。试验结果表明添加适量化学物质可以有效提高还原糖浓度。     

Starch Pasting Properties and Amylose Content from 17 Waxy Barley Lines

Starch pasting properties and amylose content from 17 waxy barley lines (waxy gene originating from indigenous lines and an artificial mutant) were analyzed using rapid viscosity analysis (Rapid Visco Analyser [RVA]). Amylose contents varied from 0% (Shikoku‐hadaka 97) to 9.5% (Shikoku‐hadaka 96) compared with 30% for normal barley. Eight parameters were obtained from RVA profiles of these lines and correlation between each of these parameters and amylose content were evaluated. These parameters include pasting temperature (PT), peak viscosity (PV), temperature at PV, minimum viscosity (MV), final viscosity (FV), breakdown (BD), setback (SB), and time maintained at >80% PV (hot paste stability [HPS]). Significant correlations (0.64 and 0.61) were found between amylose content and FV and SB, respectively. High correlation (0.72) was found between amylose content and temperature at PV. HPS calculated from RVA profiles showed the highest correlation (0.79) to amylose content. Outer part of barley grains contained higher amounts of amylose than the inner part. There was a tendency that both PT and FV positively correlated to the amylose content of these parts.     

Enzyme-Assisted Wet Separation of Starch from Other Seed Components of Hull-less Barley

A multiple enzyme cocktail containing cellulase, endo-(1→3), (1→4)-β-d -glucanase and xylanase was used in wet separation of starch, protein, β-glucan, bran, and tailings from four hull-less barleys (HB): SB94794 (0% amylose), CDC Candle (5% amylose), CDC Dawn (24% amylose), and SB550831 (40% amylose). Compared to a conventional procedure, the enzyme-assisted wet extraction reduced slurry viscosity by 50–99%, the amount of water and ethanol used in screening and β-glucan precipitation by 30–60%, and screening time by 20–80%. The enzyme-assisted extraction reduced starch contents and yields of tailings and bran fractions, resulting in a 10% increase in average starch extraction efficiency. However, β-glucan yield was reduced in the enzyme-assisted extraction, particularly in high-viscosity HB. The physicochemical properties of isolated starches were not affected by the enzyme-assisted extraction.     

Enzymatic Hydrolysis of Cellulose with Different Crystallinities Studied by Means of SEC-MALLS

The reactions of exo-cellulase （cellobiohydrolase, CBH） and endo-cellulase （endoglucanase, EG） were investigated by analyzing the insoluble residues of microcrystalline cellulose （MCC） and filter paper...