Physicochemical properties and in vitro digestibility of flours and starches from taro cultivated in different regions of Thailand

This research aimed to study physicochemical properties and in vitro digestibility of flours and starches from taro cultivated in different regions of Thailand, that is, Kanchanaburi (KB), Chiang Mai (CM), Phetchaburi (PB) and Saraburi (SB). Taro starches were extracted from taro flours using either water or alkaline extraction. The taro flours had significantly (P ≤ 0.05) larger particle size, higher pasting and gelatinisation temperatures, and resistant starch content but lower total starch content, whiteness (L* value), paste viscosities and clarity than their corresponding extracted starches. All the taro starches exhibited polygonal and irregular granules and gave A-type X-ray diffraction pattern. The alkaline-extracted taro starches had significantly (P ≤ 0.05) higher extraction yield, total starch content, L* value, pasting and gelatinisation temperatures, and paste clarity but lower granular size, amylose content, resistant starch content, paste viscosities and relative crystallinity than their water-extracted counterparts.     

不同干燥条件对张溪香芋全粉品质的影响

以张溪香芋为原料,经去皮切片蒸煮,采用日晒(约35℃)、不同温度(60℃、70℃和100℃)热风干燥四种不同干燥条件进行干燥,以干燥后粉碎所得的香芋全粉的色泽、水分、吸水性、吸油性、含糖量、蛋白质含量和颗粒分散性为指标,研究了不同干燥条件对张溪香芋全粉品质的影响。结果表明采用60℃低温热风干燥得到的张溪香芋全粉综合品质最佳,全粉色泽较浅偏白色,颗粒粒径均匀,分散性好,营养成分含量较高,具有较好的吸水性和吸油性。     

马铃薯-小麦粉混粉的理化性质与消化特性研究

以不同比例马铃薯全粉(PG)和小麦粉(WF)混粉为研究对象,探讨了马铃薯全粉与小麦粉混合比例对混粉还原糖、溶解度、膨胀度、冻融稳定性、糊化特性、快消化淀粉含量、慢消化淀粉含量、抗性淀粉含量及消化速率的影响。结果表明,马铃薯全粉具有较低的还原糖含量,较高冻融稳定性、糊化温度、快消化淀粉含量和消化速率。小麦粉的慢消化淀粉和抗性淀粉含量较高,消化速率较低。马铃薯全粉与小麦粉比例为9∶1时,溶解度和膨胀度最高。比例为1∶9时,糊化温度最低。马铃薯全粉和小麦粉的混合比例对混粉的理化性质及消化特性有明显影响。      

挤压膨化对大米粉糊化度及蛋白质体外消化率的影响

以大米粉为原料,采用挤压膨化法研究挤压膨化对大米粉糊化度及蛋白质体外消化率的影响,通过单因素及正交实验分析了物料含水量、螺杆转速、第五区温度对大米粉糊化度及蛋白质体外消化率的影响,分析得出挤压膨化大米粉的最佳参数为:物料含水量为18%,螺杆转速为190 r/min,第五区温度为190℃;在此实验条件下进行验证实验,糊化度为90.72%,蛋白质体外消化率为82.80%,挤压膨化后大米粉蛋白质体外消化率比未经挤压处理的大米粉蛋白质体外消化率提高了10.31%。本研究为大米精深加工提供一定的参考。      

Effects of alkali treatment on the in-vitro digestibility of proteins and the release of amino acids

Three protein sources, casein, soya bean and rapeseed concentrates, were subjected to alkali treatment (0.2 M, 60° C) for 2 or 6 h. The impact of these treatments on protein digestibility and on release of amino acids, especially lysinoalanine, was evaluated by an in-vitro enzymic digestion method with simultaneous dialysis of digestion products. The impairment of digestibility was higher for casein and soya bean concentrate than for rapeseed concentrate. Whatever the amount of lysinoalanine produced in each protein, it was poorly released by proteolytic enzymes. The rate of release of other amino acids was reduced by the treatments, but to different levels for each protein. Arginine and lysine were particularly affected. As can be inferred from the release of the target amino acids, the hydrolytic capacity of chymotrypsin was not specifically impaired, in contrast to that of trypsin for casein and of elastase for all protein sources. This technique was useful to evaluate quickly the effects of processing on the digestibility of proteins.     

Development of extruded snacks using taro (Colocasia esculenta) and nixtamalized maize (Zea mays) flour blends

Extruded snacks were prepared from flour blends made with taro and nixtamalized (TF-NMF) or non-nixtamalized maize (TF-MF) using a single-screw extruder. A central composite design was used to investigate the effects of taro flour proportion in formulations (0-100 g/100 g) and extrusion temperatures (140-180 °C) on the following indices: expansion (EI), water solubility (WSI), water absorption (WAI) and fat absorption (FAI). Moreover, selected TF-NMF and TF-MF extruded products were partially characterized through proximate chemical analysis, resistant starch, color, pH, water activity, apparent density, hardness, and sensory analysis. Results indicated that EI and WSI of both TF-MF and TF-NMF extrudates were significantly increased by the use of higher proportions of taro flour, while the opposite behavior was observed for the FAI (p < 0.05). Taro flour at higher proportions in both extrudates did not produce a significant change of WAI, while the use of higher extrusion temperatures only caused a significant increase of FAI in TF-MF extrudates (p < 0.05). This study showed that flour mixtures made from taro and nixtamalized maize flour produced puffed extruded snacks with good consumer acceptance.     

超声处理对黑米粉结构、理化及消化性的影响研究

为探究超声处理对黑米粉结构、理化及消化性的影响。本文以黑米粉（BRF）为研究对象,分析不同超声功率处理对黑米粉粒径分布、微观结构、结晶结构、短程有序结构、热力学、流变学和消化特性的影响。结果表明：超声处理后黑米粉颗粒被破坏,粒径减小,淀粉结晶度从45.14%降至28.53%,短程有序结构受到破坏。在理化性质方面,黑米粉吸水指数、冷水溶解度和膨胀度显著增加,分别从2.02 g.g-1、4.86%、3.20%上升至4.27 g.g-1、10.5%、6.17%。超声处理后黑米粉的糊化焓（ΔH）和储能模量（G′）与损耗模量（G′′）均降低。在消化性方面,经超声处理后黑米粉的RDS含量减少,SDS和RS含量显著升高。本研究为超声改性技术在黑米加工中的应用提供理论依据。     

Physicochemical,antioxidant properties and in vitro digestibility of wheat–purple rice flour mixtures

The physicochemical characteristics, antioxidant properties and in vitro digestibility of high‐antioxidant content flours made from different combinations of Thai purple rice flour and refined wheat flour from 25%, 50% to 75% (w/w) were investigated and these were compared with whole flour from purple rice and refined wheat flour. The increase in substitution levels of purple rice flour affected all the functional properties of flours, at the same time the levels of dietary fibre, protein digestibility and antioxidant compositions were also changed. The purple rice flour exerted a particularly strong effect on starch digestibility as the purple rice increased to 50% in the mixture. Moreover, purple rice flour showed lower amounts of rapidly digested starch (RDS), whereas slowly digested starch (SDS) of whole flour from purple rice and 75% substitution purple rice flour was found to be the highest for all samples. The in vitro starch digestibility of all samples also showed a positive correlation between dietary fibre and antioxidant compounds. Overall, the addition of purple rice flour improved the final nutritional properties, notably a lower predicted glycaemic index, and a higher antioxidant potential, which are two important nutritional properties for human health.     

Effect of drying methods on physico-chemical and antioxidant properties of date fibre concentrates

Effects of different drying methods (freeze-, oven- and sun-drying) on physico-chemical properties of date fibre concentrates (DFC) from three potential Tunisian cultivars were investigated. DFC had high contents of dietary fibre (71.01–93.46% dry matter), with high proportions of insoluble dietary fibre. Freeze dried DFC had the highest values of swelling, water holding and oil holding capacities. This drying method gave also the lightest DFC colour. Kentichi fibre produced by freeze-drying had the highest viscosity and the lowest bulkier particles. The present work assessed polyphenol content and antioxidant activity of DFC using 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. The highest polyphenol content was found for freeze dried DFC, contrary to radical scavenging activity which was not affected by drying methods. Results suggest that freeze dried DFC had the highest potential to be used as a functional ingredient in food products.     

干燥方式对淮山全粉品质的影响

通过对热风干燥、变温压差干燥、喷雾干燥和真空冷冻干燥4种干燥方式所得淮山全粉的物理特性和营养成分进行分析测定,研究了不同干燥方式对淮山全粉品质的影响。结果表明:在物理特性方面:变温压差干燥、喷雾干燥和真空冷冻干燥淮山全粉色泽好,而热风干燥褐变严重;真空冷冻干燥淮山全粉的堆积密度显著低于其他干燥方式;喷雾干燥淮山全粉的吸水性显著低于其他干燥方式,溶解度显著高于其他干燥方式,且颗粒特征较好。在营养成分方面:4种淮山全粉的营养成分均有不同程度的差异,热风干燥淮山全粉的维生素B1含量显著低于其他干燥方式;喷雾干燥淮山全粉的蛋白质、氨基酸和尿囊素含量均较高;说明喷雾干燥淮山全粉的营养成分损失较小。喷雾干燥法干燥淮山全粉品质较好,且所需干燥时间短,生产效率高、成本低。      

Effect of partitioning the nonfiber carbohydrate fraction and neutral detergent fiber method on digestibility of carbohydrates by dairy cows

Many nutrition models rely on summative equations to estimate feed and diet energy concentrations. These models partition feed into nutrient fractions and multiply the fractions by their estimated true digestibility, and the digestible mass provided by each fraction is then summed and converted to an energy value. Nonfiber carbohydrate (NFC) is used in many models. Although it behaves as a nutritionally uniform fraction, it is a heterogeneous mixture of components. To reduce the heterogeneity, we partitioned NFC into starch and residual organic matter (ROM), which is calculated as 100 ? CP ? LCFA ? ash ? starch – NDF, where crude protein (CP), long-chain fatty acids (LCFA), ash, starch, and neutral detergent fiber (NDF) are a percentage of DM. However, the true digestibility of ROM is unknown, and because NDF is contaminated with both ash and CP, those components are subtracted twice. The effect of ash and CP contamination of NDF on in vivo digestibility of NDF and ROM was evaluated using data from 2 total-collection digestibility experiments using lactating dairy cows. Digestibility of NDF was greater when it was corrected for ash and CP than without correction. Conversely, ROM apparent digestibility decreased when NDF was corrected for contamination. Although correcting for contamination statistically increased NDF digestibility, the effect was small; the average increase was 3.4%. The decrease in ROM digestibility was 7.4%. True digestibility of ROM is needed to incorporate ROM into summative equations. Data from multiple digestibility experiments (38 diets) using dairy cows were collated, and ROM concentrations were regressed on concentration of digestible ROM (ROM was calculated without adjusting for ash and CP contamination). The estimated true digestibility coefficient of ROM was 0.96 (SE = 0.021), and metabolic fecal ROM was 3.43 g/100 g of dry matter intake (SE = 0.30). Using a smaller data set (7 diets), estimated true digestibility of ROM when calculated using NDF corrected for ash and CP contamination was 0.87 (SE = 0.025), and metabolic fecal ROM was 3.76 g/100 g (SE = 0.60). Regardless of NDF method, ROM exhibited nutritional uniformity. The ROM fraction also had lower errors associated with the estimated true digestibility and its metabolic fecal fraction than did NFC. Therefore, ROM may result in more accurate estimates of available energy if integrated into models.     

湿法超微粉碎对茶叶理化性质的影响

研究了湿法超微粉碎对质量分数分别为5%和10%的茶叶悬浮液理化性质(粒度、持水力、黏度、茶多酚溶出量等)的影响。结果显示:胶体磨磨齿间隙为5μm时,对茶粉进行超微粉碎可获得粒度小于25μm的细小颗粒,而且磨齿间隙减小,茶粉的持水力、茶浆的黏度、茶多酚的溶出量都增加。     

糖类化合物对糯性谷物淀粉品质的影响

糯性谷物淀粉与普通淀粉相比具有较低的糊化温度、较强的抗老化性和冻融稳定性等特点, 在食品工业中具有更好的应用前景。糖类化合物能提高糯性谷物淀粉的糊化温度和峰值黏度, 抑制淀粉的长期回生, 影响淀粉的微观结构, 并且非淀粉类多糖能够降低糯性谷物淀粉的消化率。本文针对我国传统的粮食产物-糯性谷物, 综述了糖类化合物对糯性谷物淀粉的作用机制、理化性质和消化性。为后续糖对糯性谷物淀粉影响的研究提供更加完整的理论依据。     

马铃薯全粉对小麦粉及面条品质的影响

通过在小麦粉中添加不同比例的马铃薯全粉,测定其面筋特性、粉质特性、热特性及面条的蒸煮、质构特性和感官评价,并用扫描电镜观察面条微观结构,来探讨马铃薯全粉对小麦粉及面条品质的影响。结果表明:随着马铃薯全粉添加量的增大,混合粉湿面筋含量逐渐减少。面团的形成时间和稳定时间下降,稳定时间从5.1 min下降到0.8 min,弱化度增大。起始温度To、峰值温度TP变化不明显、终止温度TC呈上升趋势,热焓值H呈下降趋势,热焓值从257.56 J/g下降到179.46 J/g,面团的热稳定性下降。面条的干物质损失率、断条率逐渐增大。面条的硬度、弹性随着马铃薯全粉添加量的增加而逐渐减小。扫描电镜观察结果显示,随着马铃薯全粉添加量的增大面条表面变得松散,面筋断裂,淀粉颗粒暴露在面筋网络结构之外。结果得到,当马铃薯全粉添加量在20%以下时,面条具有较好的品质。      

Effect of the milling process on quality characteristics of rye flour

BACKGROUND: Most of rye flour is obtained by a gradual reduction system using roller flour mills, which generate different flour streams. The study of the different flour streams composition is necessary since it determines the flour quality and the flour uses. Four break streams and nine reduction streams were analysed for moisture, ash, starch, protein, damaged starch, falling number, amylose/amylopectin ratio, β‐glucans and colour. Mixing and pasting properties were also determined with a doughLAB and a Rapid Visco Analyser respectively. RESULTS: As the milling process advanced, moisture and starch content decreased but protein, ash, β‐glucans and damaged starch increased. The differences in composition are probably related to the effect of the roller mills and the increase in the contamination with bran. The absorption, development time, and pasting viscosity increased as the milling proceeded, in detriment of the peak time. The β‐glucan content was positively correlated to absorption, mixing tolerance index and pasting viscosity, and negatively correlated to peak time. CONCLUSION: Differences in composition, above all, in bran, showed different mixing and pasting properties in rye streams. The most different streams corresponded to the last streams in the break process, in the sizings and in the middlings. Copyright © 2008 Society of Chemical Industry     

Effect of wheat flour characteristics on sponge cake quality

BACKGROUND: To select the flour parameters that relate strongly to cake‐making performance, in this study the relationship between sponge cake quality, solvent retention capacity (SRC) profile and flour physicochemical characteristics was investigated using 38 soft wheat samples of different origins. Particle size average, protein, damaged starch, water‐soluble pentosans, total pentosans, SRC and pasting properties were analysed. Sponge cake volume and crumb texture were measured to evaluate cake quality. Cluster analysis was applied to assess differences in flour quality parameters among wheat lines based on the SRC profile. RESULTS: Cluster 1 showed significantly higher sponge cake volume and crumb softness, finer particle size and lower SRC sucrose, SRC carbonate, SRC water, damaged starch and protein content. Particle size, damaged starch, protein, thickening capacity and SRC parameters correlated negatively with sponge cake volume, while total pentosans and pasting temperature showed the opposite effect. CONCLUSION: The negative correlations between cake volume and SRC parameters along with the cluster analysis results indicated that flours with smaller particle size, lower absorption capacity and higher pasting temperature had better cake‐making performance. Some simple analyses, such as SRC, particle size distribution and pasting properties, may help to choose flours suitable for cake making. © 2012 Society of Chemical Industry     

Effects of maturity and drying method on the physico-chemical and reconstitution properties of plantain flour

Effects of maturity and drying method on physical, physico-chemical and reconstitution properties of plantain flour were investigated. Colour ( L*a*b* ) parameters of dried flours were measured, and the delta chroma (Δ C ) and colour difference (Δ E ) were calculated. Particle size, physico-chemical (pasting) using Rapid Visco-Analyser and reconstitution properties of dried plantain flour were determined. Colour parameters of foam-mat [ L* (57.56–66.33), a* (5.29–6.77), b* (11.82–13.33)], sun [ L* (60.18–67.45), a* (5.43–5.88), b* (13.19–13.25)] and oven [ L* (58.78–66.44), a* (6.08–6.33), b* (11.96–12.78)] dried flours were significantly different ( P  < 0.05). Generally, more than 40% of the flours were retained by the 710 μm sieve. Generally, peak (–2.08–166.00), breakdown (1.25–29.42), final (–1.00–298.67) and setback (1.50–156.92) viscosities varied with drying method and maturity. Peak time and pasting temperature varied from 5.20–6.87 s and 92.30–94.55 ^°C, respectively. pH (4.26–4.97), titratable acidity (0.10–0.50% citric acid), soluble solids (3.25–30.76), moisture (8.77–65.99%) and dry matter (34.01–91.23%) contents were significantly ( P  < 0.05) affected by maturity and drying method.     

Physicochemical properties,resistant starch content and enzymatic digestibility of unripe banana,edible canna,taro flours and their rice noodle products

Unripe banana, edible canna and taro flours, which have been reported to contain significant amounts of fibre, were investigated for their physicochemical properties, resistant starch (RS) content and in vitro starch digestibility, and compared with commercial high‐fibre‐modified starches from corn and tapioca. Differential scanning calorimetry showed a single endothermic peak located around 70–83 °C for the samples except the modified starches, which exhibited no transition enthalpy. The samples showed different pasting behaviours in the Rapid Visco‐Analyser (RVA) ranging from full to restricted swelling. The RS content varied from 1–26 g per 100 g dry sample, and the estimated glycaemic indices (GIs) of the samples were from 67% to 99%. Generally, samples with high RS were low in GI values. The starches produced acceptable rice noodles but with reduced rate of starch digestion and GI. The effects of the unripe banana, edible canna and taro flours on starch digestibility were either comparable or better than the commercial modified starches. These flours can substitute commercial modified starches to lower GIs of noodles and identical foods.     

Phenolic profile and carbohydrate digestibility of durum spaghetti enriched with buckwheat flour and bran

The potential of common buckwheat flour (Supreme) and bran (Farinetta) in improving upon the phenolic and antioxidant properties of durum spaghetti was investigated. The cooking quality and carbohydrate digestibility of products were also studied. Significantly large increments of between 114 and 522% for total phenolic content (TPC), 50 and 242% for total flavonoids content (TFC), and over 359% for 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant activity were recorded for uncooked experimental spaghetti samples over the control. Farinetta contributed more phenolic and antioxidant compounds than Supreme flour. Processing and cooking resulted in decreases in phenolic content and antioxidant activity. Cooking losses of up to 8.8% were recorded for the experimental samples and were higher in Farinetta-substituted products. These were generally higher than that of the control (6.3%). The introduction of buckwheat increased carbohydrate digestibility of products, but at the same time, resulted in an overall lower amount of reducing sugars after 120 min of in vitro hydrolysis. Results show that the phenolic and antioxidant properties of durum spaghetti fortified with buckwheat milling fractions can compare favourably with those of 100% whole buckwheat soba pasta, and at the same time, maintain a higher cooking quality due to the presence of semolina.     

Effect of pasta drying temperature on gastrointestinal digestibility and allergenicity of durum wheat proteins

The effects of different drying temperatures (20, 60, 85, 110 and 180 °C) on digestibility and potential allergenicity of durum wheat proteins were studied in model pasta samples, cooked in boiling water (MPSs). Increasing the drying temperature resulted in increased protein denaturation and aggregation. In vitro treatment of MPSs with pepsin and pancreatin showed similar protein degradability up to a drying temperature of 110 °C, resulting in the disappearance of the main prolamin components. In contrast, the MPS treated at 180 °C was much less digestible, due to the presence of Maillard-type protein aggregates.