Effects of non-starch polysaccharides on physicochemical properties and in vitro starch digestibility of rice starches (original) (raw)
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Food Chemistry, 2011
The starch digestibility and rheological properties of gels were evaluated in the presence of three nonstarch polysaccharides (agar, xanthan gum and konjac glucomannan) with rice starch. Each polysaccharide was added to 30% (w/w) rice starch suspension at defined concentrations and starch gels were prepared. The extent of starch gel digestibility was determined by an in vitro method and rheological properties by a dynamic oscillatory test and a compression test. The added polysaccharides suppressed starch hydrolysis in the gels compared with the control, and a concentration dependency of this suppressive effect was observed. Adding agar and xanthan gum increased the storage shear modulus (G 0 ) of starch gels, while adding konjac glucomannan decreased G 0 values. The results indicate that the suppressive effect of non-starch polysaccharides on starch digestibility appears to be not only due to the rigidity of the gel, but also the interaction between starch and non-starch polysaccharides.
Food Chemistry, 2009
Starches were isolated from three waxy rice varieties: Koganemochi (Kog), Hakuchomochi (Hak), and Kantomochi 172 (K172). Forty percent starch gels were prepared and the extent of starch gel digestibility was determined by an in vitro method. The distribution of chain lengths of amylopectin was analyzed and differential scanning calorimetry was used to analyze gelatinization and retrogradation of waxy rice starch. The K172 gel had significantly higher resistance to hydrolysis than had the other gels. The K172 starch contained lower proportions of the short chains of amylopectin and showed higher gelatinization temperature and enthalpy. The retrogradation peak was measured using waxy rice starch gels stored for 1 and 7 days at 5°C. The K172 gel was observed to retrograde more quickly and to have a greater extent of retrogradation than the other gels. The difference in amylopectin chain length distribution and recrystallinity contributed to the variation in the starch gel digestibility of waxy rice.
Carbohydrate Polymers, 2011
Digestibility of starches in four rice samples with amylose content (AC) from 1.7 to 55.4%, including a newly developed high-amylose rice, was investigated. An in vitro enzymatic starch digestion method and an AOAC method were applied to correlate rapidly digestible starch (RDS), slowly digestible starch (SDS), resistant starch (RS), and total dietary fiber (TDF) content with the AC in the samples. SDS content decreased and RS and TDF content increased with the increase in AC. The low-amylose rice (AC = 16.1%) had starch granules with weak crystalline structure and was lower in RS and TDF content even though it had a higher AC compared to waxy rice. The digestibility of the starches was not correlated with granule size or degree of crystallinity. The newly developed high-amylose rice starch exhibited a predominant B-type X-ray diffraction pattern, a great proportion of long chains in amylopectin, high gelatinization temperature, and semi-compound starch granules which are attributed to its increased resistance to enzyme digestion.
Physicochemical characteristics of rice starch supplemented with dietary fibre
Food Chemistry, 2011
Various dietary fibres (DF) from rice flours of Taichung Sen 10 (TCS10) and Tainung 67 (TNu67) rice cultivars were isolated while their roles in governing the pasting and the rheological properties of the rice starch were examined. The addition of DF (at 5 wt.% on dry starch basis), most notably from TCS10 cultivar generally caused significant increases in swelling power and pasting viscosities of 10 wt.% rice starch dispersions. Furthermore, the addition of DF was found to improve the rheological parameters of the 10 wt.% rice starch gel. Nuclear magnetic resonance (NMR) relaxation measurements revealed that the water mobility of starch gel was decreased with the addition of DF. The statistically significant factors were concluded to be arabinoxylan-related compositions for the increments of pasting and rheological characteristics, meanwhile the swelling power and setback viscosity mainly depend on b-glucan compositions and arabinose-to-xylose molar ratio (R AX).
Intrinsic and extrinsic factors affecting rice starch digestibility
Trends in Food Science & Technology, 2019
Background: The current incidence of obesity and type 2 diabetes is at global epidemic levels. To mitigate their impact, there is a need to develop starch-containing foods that give rise to a low and stable postprandial blood glucose response by increasing the proportion of slowly-digestible and indigestible carbohydrate content. Rice is an ideal target food for such dietary intervention because it is a staple food for over half the world's population. Scope and approach: The starch digestion of cooked white rice grains is usually complete or near complete upon consumption, but the rate of digestion is influenced by intrinsic food properties and extrinsic influences. This review provides an overview of the complex interplay between the starch granule and its interaction with non-starch components of the rice grain (intrinsic characteristics) as well as the effects of processing (extrinsic factors) on starch digestibility. Key findings and conclusions: The intrinsic properties of white rice grains play a significant role in starch digestibility which can be further enhanced after processing, especially by gelatinisation and retrogradation. Post-harvest storage conditions of rice were found to influence starch digestibility but this effect was temperature-dependent. Limited studies investigated starch-lipid and starch-protein interactions in rice, but changes to substrate accessibility have been implicated. Improving our understanding of the effects of processing on starch digestibility can provide an effective tool for food manufacturers to regulate starch digestibility of existing rice varieties.
Journal of Food Science and Technology, 2018
A comparison between structural, morphological, functional and digestibility studies of starches from cereals i.e. wheat (WS), corn (CS), low amylose corn (LACS) and rice (RS), tubers i.e. potato (PS) and sweet potato (SP), and legumes i.e. kidney bean (KB) were investigated. The shape of granules varied from oval to elliptical or spherical according to the source. Distribution of iso-amylase debranched materials revealed that long and short side chains fractions of amylopectin ranged from 12.6 to 33.1% and 40.5 to 52.5% respectively. KB starch showed the highest amylose content (49.50%) while RS showed the lowest (8.51%). Starches with greater granule size (PS, SP and KB) showed higher proportion of long side chains of amylopectin (AP) (Fr.II) than short side chains of AP (Fr.III). Peak viscosity (PV), breakdown viscosity (BV) and final viscosity (FV) showed significant positive relationship with Fr. II and negative with apparent amylose content (AAC) and Fr.III. Tuber starches showed greater paste viscosities followed by legume starches. Tuber and legume starches with higher apparent amylose content and Fr. II showed greater crystallinity. Gel hardness and gelatinization temperatures showed inverse relationship with RS starch having higher proportion of smaller granules (0-10 lm). KB with higher amylose content showed maximum rapidly digestible starch (RDS) content while SP showed the highest resistant starch. Above observations would be utilized in modifying properties of native starches and help in improving texture, moisture retention capacity and gel firmness of starch and its products. Keywords Starch Á Fine structure Á Scanning electron microscopy Á X-ray diffraction Á Fourier-transform infrared spectroscopy Á In vitro digestibility
Journal of Food Science and Technology-mysore, 2010
In vitro starch digestibility and glycemic indices of three rice varieties- ‘Njavara’, ‘Jyothi’ (pigmented rice verities) and ‘IR 64’ (non-pigmented rice) with similar amylose content were studied. Starch digestibility studies showed differences in glycemic response in three types of rice. The rate of starch hydrolysis was maximum (67.3%) in ‘Njavara’ rice compared to other two rice varieties. ‘Njavara’ exhibited the lowest kinetic constant (k) indicating inherent resistance to enzymatic hydrolysis. The glycemic load (GL) and glycemic index (GI) of ‘Njavara’ were similar to ‘Jyothi’ and ‘IR 64’. Resistant starch content was high in pigmented rice varieties compared to ‘IR 64’. The resistant starch content of dehusked and cooked rice increased with the storage time at refrigeration temperature (4°C). ‘Njavara’ is an easily digestible rice and can be used for baby and geriatric foods.
Comprehensive Reviews in Food Science and Food Safety, 2012
Rice starch is one of the major cereal starches with novel functional properties. Significant progress has been made in recent years on the characterization of rice starches separated from different rice cultivars. Studies have revealed that the molecular structure and functional properties are affected by rice germplasm, isolation procedure, climate, agronomic conditions, and grain development. Morphological studies (microscopy and particle size analysis) have reflected significant differences among rice starch granule shapes (polyhedral, irregular) and in granule size (2 to 7 μm). Nonwaxy and long-grain rice starches show greater variation in granular size than the waxy starches. Rice starch granules are smaller than other cereal starches with amylose contents varying from virtually amylose-free in waxy to about 35% in nonwaxy and long-grain rice starches. Amylose content appears to be the major factor controlling almost all physicochemical properties of rice starch due to its influence on pasting, gelatinization, retrogradation, syneresis, and other functional properties. Waxy rice starches have high swelling and solubility parameters, and larger relative crystallinity values than nonwaxy and long-grain starches. However, nonwaxy rice starches have a higher gelatinization temperature than the waxy and long-grain starches. The bland taste, nonallergenicity, and smooth, creamy, and spreadable characteristics of rice starch make it unique and valuable in food and pharmaceutical applications. This review provides recent information on the variation in the molecular structure and functional properties of different rice starches.