发酵法提取青稞麸皮中β-葡聚糖的工艺优化及其理化性质研究

为提高青稞麸皮β-葡聚糖的产量和纯度,选用发酵法提取制备青稞麸皮β-葡聚糖。运用单因素、正交试验确定最优提取条件,并对该条件下得到的青稞麸皮β-葡聚糖进行了分子量、单糖组成等理化分析。结果表明,发酵法提取青稞麸皮β-葡聚糖最佳工艺参数为:料液比1:6,接种0.05%高活性干酵母,在32℃条件下发酵34 h。在最优条件下生产的β-葡聚糖,得率为5.21%±0.02%,与传统水提法相比提高了60.8%,纯度为91.21%。发酵法提取的青稞麸皮β-葡聚糖理化分析特征为单糖组成主要为D-葡萄糖,其平均相对分子质量为1.366×105,水提法提取的青稞麸皮β-葡聚糖单糖组成有D-阿拉伯糖、D-半乳糖、D-木糖、D-甘露糖、D-葡萄糖,平均分子量为7.759×105。     

ENZYMIC QUANTIFICATION OF (1→3) (1→4)-β-D-GLUCAN IN BARLEY AND MALT

A simple and quantitative method for the determination of (1→3) (1→4)-β-D-glucan in barley flour and malt is described. The method allows direct analysis of β-glucan in flour and malt slurries. Mixed-linkage β-glucan is specifically depolymerized with a highly purified (1→3) (1→4)-β-D-glucanase (lichenase), from Bacillus subtilis, to tri-, tetra- and higher degree of polymerization (d.p.) oligosaccharides. These oligosaccharides are then specifically and quantitatively hydrolysed to glucose using purified β-D-glucosidase. The glucose is then specifically determined using glucose oxidase/peroxidase reagent. Since barley flours contain only low levels of glucose, and maltosaccharides do not interfere with the assay, removal of low d.p. sugars is not necessary. Blank values are determined for each sample allowing the direct measurement of β-glucan in maltsamples.α-Amylasedoes not interfere with the assay. The method issuitable for the routineanalysis of β-glucan in barley samples derived from breeding programs; 50 samples can be analysed by a single operator in a day. Evaluation of the technique on different days has indicated a mean standard error of 0–1 for barley flour samples containing 3–8 and 4–6% (w/w) β-glucan content.     

Probabilistic methodology for assessing changes in the level and molecular weight of barley β-glucan during bread baking

The objective of this study was to create a probabilistic model to assess changes in the levels and molecular weight (Mw) of β-glucan during the bread baking process using Monte Carlo simulation techniques. Three different composite flours were formulated by substituting wheat flour (WF) with barley whole meal flour (BWMF), barley straight grade flour (BSGF) or barley fibre rich fraction (BFRF). The β-glucan level in the flour increased significantly (by approximately 10-fold) when barley was substituted for WF. The baking process resulted in approximately a 47–48% reduction in the β-glucan level in the baked bread (base-line model). The base-line model observed ∼25% and 7% reduction in high molecular weight (HMw) and medium molecular weight (MMw), respectively and a subsequent increase in low molecular weight (LMw). The analysis also showed the importance of various steps involved in bread baking, such as mixing time (Mt), fermentation time (Ft) and baking (BGloss), on the level and Mw of β-glucan in baked breads. A parallel experimental validation study provided confidence in model predictions of β-glucan levels. This study aids in optimising the various unit operations involved in the bread baking process to give a final product with increased nutritional qualities.     

Effect of formulation on protein breakdown, in vitro digestibility, rheological properties and acceptability of tarhana, a traditional Turkish cereal food

Three formulations of tarhana, a traditional Turkish fermented yogurt-wheat mixture used in soups, were prepared in the laboratory. The effects of white or wholemeal wheat flours and amount of yogurt on the protein breakdown, rheology and acceptability of the samples were measured and the samples were compared with single samples of homemade and commercial tarhana from Turkey.
Replacement of white wheat flour with wholemeal flour and increasing the yogurt had little effect on protein breakdown, but the true- to crude-protein ratio fell slightly during fermentation. Tarhana soups behaved as pseudoplastics (ñ < 1) at 80°C, and those with ñ values (>0.8) closer to Newtonian flow (ñ= 1) were most liked in mouth feel; however high apparent viscosity and samples with less liked mouth feel were not less liked in overall acceptability than the commercial sample. In vitro digestibility of commercial tarhana was lower than the laboratory prepared tarhana.     

Physicochemical Characteristics and Functional Properties of Starch from a High β-Glucan Waxy Barley

The physicochemical properties and functional characteristics of starch from a high β-glucan waxy barley were compared with those of starches isolated from normal and high amylose barleys. Amylose content of the starches ranged from 1.9 to 34.8%. There was no relationship between amylose content and water binding capacity and gelatinization temperature of the starches. Amylose content and swelling power as well as enzyme susceptibility were negatively correlated. Waxy barley starches had a lower solubility than amylose-containing starches. High amylose barley starch registered no swelling in the Amylograph. Amylose content in starch proved to be very important for good bread- and cake baking quality. Waxy starches did not produce acceptable breads and cakes. The starch from the high β-glucan barley variety “Shonkin” will be suitable as a thickening agent, but not as an ingredient in bakery products.     

Nutritional and functional performance of high β-glucan barley flours in breadmaking: mixed breads versus wheat breads

The ability of high β-glucan barley (HBGB) flour versus regular commercial barley (CB) to make highly nutritious wheat (WT) blended breads meeting functional and sensory standards has been investigated. Mixed breads obtained by 40 % replacement of WT flour by HBGB flours are more nutritious than those replaced by CB flours and much more than regular WT flour breads in terms of elevated levels of dietary fibre fractions (soluble, insoluble, resistant starch and β-glucans), slowly digestible starch subfraction and bioaccessible polyphenols providing higher antiradical activity. WT/CB and WT/HBGB breads can be, respectively, labelled as source of fibre (3 g DF/100 g food) and high-fibre breads (6 g DF/100 g food), according to Nutritional Claims for dietary fibre foods. The consumption of 100 g of WT/HBGB can meet up to almost 50 % the required dietary fibre, providing a β-glucan intake high enough to meet the requirements of the EFSA health claim (3 g/day), contributing a reduced blood cholesterol level. The techno-functional performance of fresh blended breads and the sensory appreciation were in general preserved or even improved.     

Effects of genotype and environment on β-glucan and dietary fiber contents of hull-less barleys grown in Turkey

In this study, the effects of cultivar and environment on β-glucan and total dietary fibre (TDF) contents and various quality characteristics of hull-less barley samples grown in Turkey were investigated. There were significant differences among the barley genotypes and different locations in terms of β-glucan and TDF content (p < 0.05). Significant correlations were found between β-glucan content and some quality criteria (sieve analysis and 1000 kernel weight). The correlations between TDF and grain yield, hectolitre weight, 1000 kernel weight and protein content were also generally significant. These results indicated that environmental and genetic factors are involved in the total β-glucan content of barley.     

Carbohydrate content and structure during malting and brewing: a mass balance study

A holistic view of the fate of barley starch, arabinoxylan and β-glucan throughout malting and brewing is largely missing. Here, an industrial scale malting trial and pilot brewing trial were performed, and the concentration and structural characteristics of carbohydrates were analysed at 28 key points in the process. The barley starch content decreased during malting from 75.0% to 69.7%. During mashing, malt starch was converted to fermentable sugars (75.3%), dextrin (22.8%) or was retained in spent grains (1.8%). Arabinoxylan was partially hydrolysed during malting. Despite mashing-in at 45°C, no further solubilisation of arabinoxylan was observed during mashing. However, the average degree of polymerisation of the soluble arabinoxylan fraction decreased slightly. During fermentation, the arabinoxylan content decreased to 2.5 g/L. The amount of barley β-glucan decreased gradually in time during malting. Of the solubilised β-glucan, 31% was retained in the spent grains during wort filtration, slightly lowering the β-glucan content in the wort. The β-glucan content remained at 0.5 g/L during fermentation. Sucrose was hydrolysed during mashing, probably by barley invertases. From the total amount of malt used, 41.0% was converted to fermentable sugars. This mashing yield could have been improved by the full hydrolysis to fermentable sugars of the present β-glucan (to 41.1%), the remaining starch in spent grains (to 42.0%) and dextrin in wort (to 50.3%). These results provide more insight into the carbohydrate conversions during malting and brewing and can act as a baseline measurement for future work. © 2020 The Institute of Brewing & Distilling     

β-GLUCAN AND β-GLUCAN SOLUBILASE IN MALTING AND MASHING

During malting the water-insoluble β-glucan of barley is diminished whilst water-soluble gum is little decreased. The amount of β-glucan surviving into malt depends on variety but barleys rich in glucan give malts with high β-glucan levels. The β-glucan content of barley depends on variety and growth site. β-Glucan solubilase survives mashing and catalyses the release of hemicellulose into solution. There is no correlation between the β-glucan content of malt and the amount released into wort. However, barley adjuncts containing high levels of β-glucan give worts rich in β-glucan. β-Glucan dissolution in mashing is dependent on time, temperature, grist particle size and liquor: grist ratio. Use of adjuncts derived from barley contribute relatively more β-glucan in wort, coinciding with reduced rates of wort separation, but these can be increased by using a β-glucanase produced by growing the fungus Trichoderma viride on spent grains.     

Effects of hull-less barley flour and flakes on bread nutritional composition and sensory properties

Barley is a desirable food ingredient, with health benefits provided by a β-glucan fibre fraction. A hull-less barley flour and flakes were incorporated into white and wholegrain wheat bread in quantities usually applied in practice. The breads were evaluated for nutritional composition and sensory properties and compared to standard products as controls. The supplemented breads were high in fibre, zinc and selenium content. It was estimated that a 300-gram daily portion of such breads could meet up to 40% of dietary recommended intakes for selenium and 70–75% of recommended daily values for β-glucan. Regarding sensory quality, the only significant differences (p < 0.05) were higher taste and lower volume in the white supplemented breads and lower crumb elasticity in the white bread made with barley flour. Hull-less barley can substantially contribute to an adequate intake of selenium and β-glucan. In addition, supplemented breads were not found to pose a significant risk, with regard to excessive intakes of heavy elements (Pb, Cd, As).     

EFFECTS OF CULTIVAR AND ENVIRONMENT ON β-GLUCAN CONTENT AND MALTING QUALITY OF TURKISH BARLEYS

Eight barley cultivars grown under the same agronomic conditions and samples of Tokak cultivar grown at six different sites of Turkey were used in this study. There were significant differences among the barley cultivars and growing locations in terms of β-glucan content (p<0.05). Among malt quality criteria tested for the 8 barley cultivars; friability, viscosity, Kolbach index and extract difference showed significant correlations (p<0.05) with the total β-glucan content. Similar correlations were also observed between the malt quality criteria (Kolbach index and extract difference) and β-glucan contents for the Tokak samples grown at different sites.     

Effects of various phytase sources on phytic acid content,mineral extractability and protein digestibility of tarhana

Changes in phytic acid (PA), HCl-extractability (HCl-E) of some minerals and in vitro protein digestibility (IVPD) during the production of tarhana prepared with the addition of different phytase sources (bakers’ yeast, barley malt flour and microbial phytase) were investigated. PA content of tarhana decreased significantly (p < 0.01) after addition of the yeast, malt and phytase. With respect to wheat flour used as raw material, PA content of tarhana decreased by 95.3%. After tarhana production, average values of HCl-E of Ca, Mg, Zn and K, and also IVPD of tarhana increased up to 80.2%, 86.4%, 73.9% and 92.6%, and 91.9%, respectively. Significant negative correlation coefficients were found between the PA and HCl-E of the minerals, and also IVPD. Tarhana production processes, including fermentation, drying and grinding, were able to remove the antinutritional effects of PA. Each one of the phytase sources used alone decreased the PA content to a limited extend. The results show that tarhana has good potential in the total amounts and bioavailability of the minerals and proteins.     

Effect of Microwave Radiation Pretreatment of Rice Flour on Gluten-Free Breadmaking and Molecular Size of β-Glucans in the Fortified Breads

Cereal β-glucan concentrates can be used in gluten-free breads to improve dough handling properties and quality of final products as well as to enhance their nutritional value; however, the presence of endogenous β-glucanases in rice flour, in combination with prolonged mixing, fermentation, and proofing time, can cause a substantial reduction in β-glucan molecular weight, affecting detrimentally their efficacy for bioactivity. In this study, microwave (MIWA) heating was applied to the rice flours before breadmaking at different flour water contents (13–25%) and treatment times (0-4 min) to reduce β-glucanase activity. Gluten-free breads made from the MIWA-treated rice flours were fortified with oat β-glucan concentrate to enhance their nutritional profile. The molecular weight of added β-glucan in the final products increased with increasing both flour water content and time of MIWA treatment, reflecting the magnitude of residual β-glucanase activity in the flour. Pretreatment with MIWA radiation for 4 min of the rice flour tempered at 25% moisture resulted in negligible residual β-glucanase activity and preserved to a great extent the molecular weight of β-glucans in the enriched breads. End-product quality was not affected by flour MIWA pretreatment, and even a slightly higher loaf specific volume was noted for breads made from the MIWA-treated flours (4 min MIWA at 25% moisture content) compared to that of untreated flour. These findings can contribute to the improvement of nutritional value of rice-based gluten-free breads for celiac consumers as well as of any β-glucan-containing yeast-leavened bakery product without altering its sensorial attributes. Additional studies are still required for further evaluation of the effect of more intense microwave treatment on rice flour and its application on breadmaking.     

Polymeric protein formation during pasta-making with barley and semolina mixtures,and prediction of its effect on cooking behaviour and acceptability

Spaghetti were produced in a pilot plant from semolina and semolina blended with increasing amounts of barley flour. According to size exclusion high-performance liquid chromatography (SE-HPLC), barley proteins interact with semolina proteins during pasta making, forming polymers of high molecular weight. Of these, the unextractable polymeric proteins (UPP) were at significantly higher concentrations than in spaghetti made from semolina. The decrease of both S–S bonds and –SH free groups in barley semolina spaghetti, with respect to that made of semolina, suggested that polymerisation among the different classes of proteins involves a new bonding arrangement. Due to β-glucan hydrophilicity and competition with starch for water, the replacement of increasing amounts of semolina with barley flour was able to increase the optimal cooking time. The sensory properties of composite spaghetti were judged as better than the control because of the higher firmness and the lower bulkiness and stickiness of the former.     

The use of β-glucan as a partial salt replacer in high pressure processed chicken breast meat

The effect of various ingredients such as sodium chloride (NaCl), sodium tripolyphosphate (STPP) and β-glucan (BG) on the biochemical properties of chicken breast proteins during temperature assisted high pressure processing was studied. Total protein solubility revealed that 600 MPa pressure and 40 ^oC are critical for the denaturation of proteins in STPP samples. Increase in reactive sulfhydryl groups with pressure indicate the exposure of buried sulfhydryl groups. Hydrophobicity and sulfhydryl contents revealed that hydrophobic interaction and disulphide bond formation are responsible for gel formation. The study revealed that 40 ^oC and 400/600 MPa pressure is optimum for high pressure processing of chicken breast meat. Addition of β-glucan with reduced NaCl and in the absence of sodium tripolyphosphate could produce gels with similar properties to those with 2.5% NaCl addition. Hence it is proposed that β-glucan can be used to reduce NaCl content of chicken products produced by temperature assisted high pressure processing.     

Effects of barley flour and wheat bran supplementation on the properties and composition of Turkish flat bread, yufka

In this study, the effects of increasing levels of wheat bran and barley flour on dough properties and yufka quality were investigated. Yufka is a flat, circular, cream-colored unleavened bread commonly consumed in Middle Eastern countries. Flours of wheat varieties Gün and Gerek, flour of barley variety "Tokak" and Gerek bran mixture were used. Part of the wheat flours were replaced with barley flour at 10, 20, 30, and 40% levels and bran mixture at 5, 10, 15, and 20% levels. Yufka samples were subjected to sensory analysis for color and appearance, shape and symmetry, taste and aroma, mouthfeel and flexibility. Increasing levels of bran and barley flour caused slight decreases in all sensory properties. Detrimental effects of barley flour and bran on yufka properties were nearly the same. But all yufka samples were considered acceptable. It was observed that bran caused more changes in colors of yufka samples than barley flour. Yufka samples supplemented with bran had given lower L values and higher a and b values as compared to the barley flour added ones. In all samples, the effect of increasing levels of barley flour on residual #-glucan was found to be insignificant in both cultivars. As expected, acid detergent fiber (ADF) and neutral detergent fiber (NDF) values increased with increasing levels of bran and the changes in both cultivars were similar.     

Effect of Drying Methods on Functional Properties of Tarhana: A Wheat Flour-Yogurt Mixture

ABSTRACT: Changes in functional and sensory properties of tarhana prepared by different drying methods were investigated. While tunnel-dried (TD) tarhana had significantly ( P < 0.05) higher foaming capacity compared to freeze-dried (FD), home-microwave-oven-dried (HMD) and industrial-microwave-dried (IMD) samples, the FD tarhana showed the highest protein solubility. All tarhana samples exhibited pseudoplastic behavior described by power-law model. The drying methods used appeared to influence water and oil absorption capacities and emulsifying activity of tarhana. Microwave-dried tarhana exhibited higher overall sensory rating and color acceptability.     

Preparation of β-glucan and antioxidant-rich fractions by stone milling of hull-less barley

Stone milling of hull-less barley in combination with size-based separation of the milled fractions was used for preparation of flours with different compositions of macronutrients and bioactive compounds. According to similar compositions, specific milled fractions were combined to define three flours. The flour with the largest mass fraction (~70%) comprised particle sizes < 124 μm, which showed lower fibre, residual ash and antioxidant contents than the unfractionated flour. The flour with particles from 124 to 250 μm (~20% mass fraction) had >twofold greater β-glucan content, and the flour with particles > 250 μm (~10% mass fraction) had >threefold greater content of antioxidants than unfractionated flour. Each of these three flour fractions represents valuable material that can be incorporated into bakery products to enhance functional and health-related properties. Large enrichment factors of bioactive compounds in barley flours can be obtained using small-scale and widely available milling equipment.     

青稞β-葡聚糖对淀粉体外消化性的影响

对比青稞全粉和普通小麦粉体外消化性,研究青稞β-葡聚糖质量浓度和分子质量对青稞淀粉体外消化性的影响,从青稞β-葡聚糖流变学特性及其与α-淀粉酶的相互作用方面,探究青稞降血糖的可能机理。结果表明,青稞全粉中淀粉消化率明显低于小麦粉;随青稞β-葡聚糖质量浓度和分子质量的增大,其溶液黏弹性增大,对α-淀粉酶活性的抑制效果越明显,延缓淀粉体外消化效果越显著。青稞β-葡聚糖形成的高黏性环境是青稞全粉低淀粉消化率的潜在机理。     

The behaviour and susceptibility to degradation of high and low molecular weight barley β-glucan in wheat bread during baking and in vitro digestion

The behaviour and susceptibility to degradation of a high molecular weight (HMW) and low molecular weight (LMW) barley β-glucan in white bread during manufacture and in vitro digestion were investigated. The incorporation of both HMW and LMW barley β-glucan resulted in stiffer dough, lowered loaf volume and height compared to the control. The HMW barley β-glucan caused the greatest loss of dough and bread quality. Breads with HMW and LMW barley β-glucan exhibited attenuated reducing sugars release (RSR) over a 300 min in vitro digestion compared to the control, with generally no difference between the breads. HMW barley β-glucan was degraded during bread manufacture; however, degradation of the LMW barley β-glucan was not apparent. An in vitro digestion did not result in any further degradation of the molecular weight (MW) of either barley β-glucan.