Effect of physico‐chemical properties of tropical starches and hydrocolloids on rice gels texture and noodles water retention ability

The links between the physico‐chemical properties of rice flour (RF), cassava (CS), sago (SS), canna (CaS), sweet potato (SPS), and mung bean (MS) starches, and the gelling properties of rice flour blends with these starches in different proportions (0, 20, 40, 60, 80, and 100% pure starches) and with xanthan (XG) and carrageenan (CG) gums were studied. Water retention ability of starches and hydrocolloids blends in noodle systems during drying at 40°C was also investigated. The mean granule diameter and AM content values of RF, CS, SPS, SS, CaS, and MS were in the range of 12.8–41.0 µm and 21.9–39.4%, respectively. Thermal properties showed significant differences (p < 0.05) between the starches in terms of gelatinization temperature and enthalpy, as well as retrogradation tendency. Different starches produced gels with a wide range of textural properties. Results confirmed the role of AM content in determining the gel strength, and indicated a possible role of retrogradation in increasing the dissipation of mechanical energy during compression and relaxation tests, which can have an effect on mouth feel. Blends of RF with other starches and hydrocolloids generally improved the characteristics of RF‐based gels, by increasing gel strength. In particular, the use of MS markedly increased the strength of RF‐based gels. Addition of hydrocolloids significantly reduced the drying rate of noodles, although overall water retention ability was reduced only to a limited extent. This may be used to produce starch‐based products, especially noodles, in a range of desired characteristics.     

Controlling rheology and structure of sweet potato starch noodles with high broccoli powder content by hydrocolloids

Incorporating high volume fractions of broccoli powder in starch noodle dough has a major effect on its shear modulus, as a result of significant swelling of the broccoli particles. Several hydrocolloids with distinct water binding capacity (locust bean gum (LBG), guar gum, konjac glucomannan (KG), hydroxypropyl methylcellulose (HPMC) and xanthan gum), were added to systems with 4 and 20% (v/v dry based) broccoli particles, and the effect of this addition on dough rheology, mechanical properties and structure of cooked noodles was investigated. Hydrocolloids with low (LBG and guar gum) and intermediate (KG) water binding capacity had no significant effect on shear rheology of the dough. Adding hydrocolloids with high water binding capacity (HPMC and xanthan gum) decreased the shear modulus of dough with 20% broccoli particles significantly. CLSM analysis of cooked noodles showed that in samples containing xanthan gum there was also an inhibition of swelling of starch granules. Strength and stiffness of cooked noodles with 20% broccoli particles were higher for samples containing xanthan gum, than samples without xanthan gum. The cooking loss and swelling index of samples with added hydrocolloids were slightly lower than samples without hydrocolloids. Our results showed that hydrocolloids with high water binding capacity can be used to control the degree of swelling of vegetable particles and starch granules in starch noodle products, and thereby control both dough rheology and textural properties of the cooked noodles.     

Quality improvement effects of electrolyzed water on rice noodles prepared with semidry-milled rice flours

Food Science and Biotechnology - To investigate the effects of electrolyzed water treatment on the qualities of rice noodles prepared with semidry- milled rice flour, pasting properties and thermal...     

Retarding effects of organic acids,hydrocolloids and microwave treatment on the discoloration of green tea fresh noodles

Superfine green tea powder (SGTP) was premixed with organic acids (ascorbic acid, citric acid) and hydrocolloids (sodium alginate, curdlan), and then mixed with microwave-treated wheat flour to produce green tea fresh noodles (GTFN). Darken-retardant effects of organic acids, hydrocolloids and microwave treatments on GTFN were evaluated, as well as pH, polyphenol oxidase activity, sensory and microstructure characteristics. The results revealed that organic acids exhibited a suppressive effect on discoloration, among which citric acid (CA) displayed more efficient influence with lower pH. After adding hydrocolloids and microwave treatments, retardant effects exhibited more significant (P < 0.05). Specifically, employing citric acid 0.6 g/100 g, sodium alginate 0.2 g/100 g, and 800 W microwave (MW) 50 s would contribute to lower darkening index ΔE^* (24 h, 25 °C) at 3.88 ± 0.314, 4.94 ± 0.297, 2.78 ± 0.212, respectively. Furthermore, the combined effect of the above process restrained discoloring rate considerably (ΔE^* = 1.92 ± 0.101), also provided pleasant sensory characteristics. The confocal scanning laser microscopy (CSLM) images demonstrated the microstructure of the noodle was strengthened compared with blank GTFN, and sodium alginate could serve as a binding agent to parcel SGTP and starch granules.     

Stabilisation mechanism of various inulins and hydrocolloids: Milk–sour cherry juice mixture

Milk–fruit juice mixtures, such as the mainly acidic nutraceutical soft drinks, usually suffer from phase separation due to aggregation of caseins at low pH. In this study, short‐chain inulin (SCI), native inulin (NI), long‐chain inulin (LCI) and a combination of long‐ and short‐chain inulins (LCI:SCI) (MIX) in different ratios (20:80, 50:50 and 80:20) were added (up to 10% w/v) to a milk–sour cherry juice mixture and their stabilisation mechanisms investigated using rheological, microstructural and zeta potential observations. In addition, gum tragacanth (GT) and Persian gum (PG) as adsorbing and guar gum (GG) as nonadsorbing hydrocolloids were combined with inulin to enhance their stabilising properties. Finally, sensory analyses were carried out on the stabilised samples. According to our findings, LCI fully stabilised the mixture (8% w/v), while LCI: SCI and NI only reduced phase separation at very high concentrations, and SCI had no significant effect on the stabilisation. Moreover, no inulin aggregates and rheological changes were observed with SCI. However, LCI, LCI: SCI and NI formed inulin aggregates and the mixtures became even more viscous and thixotropic (LCI > LCI: SCL > NI). Based on these observations, it can be concluded that chain length and concentration are two important factors that affect the functionality of inulin. On the other hand, the combination of inulin with GT and PG did not have any pertinent effect on the stabilisation. However, the mixture of inulin and GG could stabilise the mixtures at certain ratios and concentrations. Furthermore, in mixtures containing GG and SCI, GG played the main role in the stabilisation by increasing the viscosity and forming gel network.     

半干米粉的发酵工艺优化及蒸煮品质、质构特性分析

以半干米粉的吐浆率和质构特性作为评价指标,探讨自然发酵和接种发酵对半干米粉蒸煮品质和质构特性的影响,并在单因素实验基础上应用响应面法优化发酵工艺,得出较优的发酵工艺条件,并对其进行蒸煮品质和质构特性分析。结果表明：半干米粉在(25±2)℃的温度下自然发酵3 d时蒸煮品质和质构特性的表现是能接受的,而接种发酵在发酵温度35℃、菌种添加量106 CFU/g时仅发酵48 h蒸煮品质和质构特性就达到最佳;响应面优化接种发酵工艺的参数为发酵温度35℃、发酵时间52 h、菌种添加量106 CFU/g,在此条件下半干米粉吐浆率为(4.32±0.05)%。本实验获得的半干米粉与不发酵的样品对比可知,硬度提高了55.61%、黏性降低了92.88%、弹性提高了4.34%、咀嚼性提高了125.89%、内聚性提高了6.46%、回复性提高了8.46%、吐浆率降低了50%。     

Effects of non-starch hydrocolloids on the physicochemical properties and stability of a commercial béchamel sauce

The aim of this study was to investigate the effects of non-starch hydrocolloids (NSH) on the physicochemical properties and stability of a béchamel sauce. Three different NSH (guar gum, xanthan gum and carboxymethylcellulose) were added at two concentrations (0.10 wt.% and 0.25 wt.%) hereby replacing an equal amount of modified starch. Sauce batches were stored at refrigerated temperatures during four weeks and were rheologically characterized at day 2, 16 and 30 after preparation. The addition of all hydrocolloids caused a marked increase of the consistency index compared to the model system whereas this parameter decreased for all sauces during refrigerated preservation. The yield stress was also increased by the NSH. Furthermore all studied NSH reduced the amount of syneresis, with xanthan gum being the most effective. Besides, sensory tests demonstrated that there were no significant differences in taste and general preference between the hydrocolloid sauces and the model system.     

Effects of banana flour and β-glucan on the nutritional and sensory evaluation of noodles

The purpose of this study is to determine the nutritional and sensory attributes of the yellow alkaline noodle (YAN) prepared from 30% matured green banana (Musa acuminata × balbisiana Colla cv. Awak) flour (BF) and with addition of 10% oat β-glucan. The substitution of wheat flour with BF resulted in significantly (p < 0.05) higher total dietary fibre (TDF), and especially insoluble dietary fibre (IDF), resistant starch (RS) and total starch contents. Thirty percent of BF significantly (p < 0.05) improved the antioxidant properties (AP) of noodles in terms of the total phenolic (TP) content and inhibition of peroxidation. Noodle incorporated with 30% BF and added oat β-glucan showed the lowest GI and carbohydrate digestibility rate, and higher concentrations of essential minerals (magnesium, calcium, potassium and phosphorus) and proximate components, with the exception of crude fat, when compared to the control. Sensory evaluation indicated that the quality of the 30% BF-substituted noodle was comparable to the control.     

Evaluation of commercial microbial hydrocolloids concerning their effects on plasma lipids and caecal formation of SCFA in mice

Exopolysaccharides (EPS) are excreted by microorganisms into the surrounding environment and have been shown to have various physiological effects and are commonly used as food additives due to their rheological properties. Four commercially available microbial EPS with different polymeric structures and composition were tested in LDL receptor knock-out mice to investigate their effect on blood cholesterol, lipoproteins and caecal formation of SCFA. After four weeks on a Western diet supplemented with 4% EPS there were significant increases in caecal content and caecal tissue weight for the EPS groups compared to the control. The total pool of caecal short chain fatty acids was increased when mice were fed scleroglucan, xanthan and dextran. There were no differences in plasma cholesterol levels on the experimental diets compared to the control. Plasma triglycerides did not differ between groups. The results indicate that EPS supplementation to a Western diet may help in maintaining a healthy intestinal environment.     

Influence of hydrocolloids on dough handling and technological properties of gluten-free breads

BackgroundThe development of gluten-free breads has attracted great attention as a result of better diagnoses of relationship between gluten-free products and health. The market demand for gluten-free products is increasing day by day due to growing number of celiac disease cases. Development of gluten-free bread remains a technological challenge due to the key role of gluten in the breadmaking process and in bread structure, appearance, texture and shelf life.Scope and approachThis review covers recent advances in the application of hydrocolloids in dough handling, technological and nutritional properties of gluten-free breads, which affect its quality and value.Key findings and conclusionsGluten-free breads results from the combination of different ingredients and hydrocolloids required to building up network structures responsible for bread quality. Various gluten-free formulations have applied hydrocolloids to mimic the viscoelastic properties of gluten. In addition, the impact of different hydrocolloids on the characteristics of dough and bread quality is known to be highly dependent on raw materials, the nature and quantity of hydrocolloids. Hydrocolloids improve the texture, increase the moisture content and extend the overall quality of bread. The results of the reviewed studies indicate that some of those products were acceptable and presented similar or better sensory attributes than control formulations and some were even comparable to their wheat-based counterparts. Based on successful applications of hydrocolloids, it is suggested that novel nutritious ingredients, combined with hydrocolloids can be added to gluten-free bread formulations to improve the quality of life.     

Effect of rice wax on water vapour permeability and sorption properties of edible pullulan films

Edible films were prepared using various ratios of pullulan and rice wax. Freestanding composite films were obtained with up to 46.4% rice wax. Water vapour barrier properties of the pullulan film were improved with increased addition of rice wax. Moisture sorption isotherms were also studied to examine the impact of rice wax on the water sorption characteristics of the film. The Brunauer–Emmet–Teller (BET) and Guggenheim–Anderson–de Boer (GAB) sorption models were tested to fit the experimental data. The models gave a good fit up to the water activity (a_w) of 0.55 for BET and a full range of a_w from 0.12 to 0.95 for GAB (R² ? 0.98). Changes in the sorption parameters, particularly such as the decrease in monolayer moisture content (Mo), reflect the trend of reduced hydration capacity with increased addition of rice wax, providing useful information on water activity conditions to achieve stability for the composite films.     

Effect of starch and non-starch components on water migration,microstructure, starch retrogradation and texture of flat rice noodles made from different rice varieties

Effects of starch and non-starch components on rice noodle quality, water migration during rehydration, texture, microstructure and starch retrogradation of dried rice flour and rice starch noodles made from five rice varieties with similar high amylose contents were examined. Rice noodle qualities depended mainly on starch properties and to a lesser extent on the presence of non-starch components. Elongation of rice flour noodles was lower than rice starch noodles due to the presence of non-starch components that interrupted the starch network. Non-starch components reduced cooking loss of flour noodles in some varieties. Water migration in rice flour noodles with a looser microstructure was faster than in rice starch noodles. Nuclear magnetic resonance imaging revealed different water migration speeds in rice flour noodles among varieties, related to noodle microstructure and retrogradation properties. For production of good quality rice noodles, manufacturers should consider not only amylose content but also non-starch components.     

功能性米线配方优化及品质分析研究

本研究以早籼米、苦荞、黑麦和绿豆为原料加工低消化率的功能性米线,应用D-混料实验设计以期得到eGI值、蒸煮性质和感官特性同时较佳的功能性米线。获得原料的最佳配比,并分析各原料比例与米线功能和品质的关系。结果表明：经过优化后的功能性米线配方为苦荞6.43%、黑麦5.00%、绿豆20.85%、早籼米67.72%,其eGI值85.29、蒸煮性质-0.71、感官特性84.00。功能性米线原料与纯米线原料相比,其糊化黏度值、衰减值和回生值降低,糊化起始温度（To）、峰值温度（Tp）和最终温度（Tc）升高,而米线产品的硬度、黏着性、胶粘性、咀嚼性和回复性显著降低。研究结果可为功能性米线的开发提供参考,为主食营养化的实现开拓新的途径。     

Composite wheat–germinated brown rice flours: selected physicochemical properties and bread application

Selected physicochemical properties of composite [wheat/germinated brown rice (GBRF)/germinated glutinous brown rice (GGNBRF)] flours at 100:0:0 (control), 70:30:0, 60:30:10, 60:40:0 and 50:40:10 (%) were evaluated. Germination (steeping at pH 3 for 24 h at 35 °C) increased free gamma‐aminobutyric acid from 2.11 to 32.7 and 2.41 to 30.69 mg per 100 g flour for GBRF and GGNBRF, respectively. The 60:30:10 and 50:40:10 composite flours exhibited the lower peak viscosity (70.42 and 68.54 RVU, respectively). The setback viscosity of composite flours containing GGNBR was significantly lower than other flours. The presence of GBRF and GGNBRF significantly lowered specific volume and expansion ratio of breads. However, all sensory liking scores, except for appearance, were not significantly different among composite flour breads. Overall liking scores of all breads ranged from 6.8 to 7.2 (like moderately). This study demonstrated feasibility of incorporating GBRF and GGNBRF up to 50% by weight in bread formulations without compromising sensory liking.     

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 freezing temperature on rehydration and water vapor adsorption characteristics of freeze-dried rice porridge

Effect of freezing temperature of rice porridge on quality properties of freeze-dried rice porridge was investigated at various temperatures. Slow freezing produced porous freeze-dried rice porridges with large pores and more brittle structure than rapid freezing. All the quality properties tested were greatly influenced by both freezing temperature and temperature for the property evaluation. Both the initial rehydration ratio and the dissolution time of the freeze-dried rice porridge decreased with increase in water temperature. Results on the effect of freezing temperature on rehydration ratio and dissolution time indicated slow freezing is more preferable for the freeze-dried rice porridge. The Peleg model was fitted better than the Singh and Kulshrestha model to explain the water vapor adsorption kinetics. The activation energy for the water vapor adsorption of the freeze-dried rice porridge determined by using the Peleg model ranged 16.2-23.1 kJ/mol depending on the freezing temperature.     

Effect of dry- and wet-milled rice flours on the quality attributes of gluten-free dough and noodles

The rheological and cooking properties of gluten-free noodles prepared with dry- and wet-milled rice flours were characterized. Dry-milled rice flour with a higher degree of starch damage exhibited greater water hydration properties than wet-milled rice flour at room temperature. However, the pasting results of rice flour suspensions demonstrated that wet-milled rice flour showed a higher value of peak viscosity due to its great swelling power upon starch gelatinization. The similar thermo-mechanical tendency was observed in a rice dough system by Mixolab. In the planar extensional test, the noodle dough sample prepared with dry-milled rice flour exhibited higher elongational viscosity which could be favorably correlated to more resistance of dry-milled rice noodle strands to extension. When rice noodles were cooked, increased cooking loss was observed in dry-milled rice noodles which was attributed to great water solubility derived from a higher degree of starch damage.