ABSTRACT
Effects of sodium carboxymethyl cellulose (CMC) and hydroxypropyl methyl cellulose (HPMC) on the pasting, viscoelastic, and morphological properties of rice starch gel were studied. The addition of CMC increased the peak and trough viscosities, while decreased the final and setback viscosities of rice starch. The peak and trough viscosities of rice starch gel were only little affected by the addition of HPMC. The dynamic viscoelastic result showed that the addition of CMC significantly increased the values of storage modulus (G') and loss modulus (Gâ³), while reduced the value of tanδ as compared to the control sample. Only a small increase in values of G' and Gâ³ was observed in the case of HPMC. The rice starch gel with CMC addition exhibited higher resistances to the stress and produced a stronger gel network. The creep recovery data were well fitted by a four-element Burger's model. Furthermore, the morphological characteristics were in agreement with the finding of rheological results. It was concluded that the addition of CMC and HPMC modified the rheology of rice starch gel in different ways and interacted under different models based on their molecular structures. PRACTICAL APPLICATIONS: Gluten-free foods such as rice cake are essential for people who suffer from celiac disease which is a digestive disorder caused by the consumption of grains containing gluten. The use of CMC and HPMC represents the most widespread approach used to mimic gluten in the manufacture of gluten-free breads based on rice starch, due to their structure-building and water-binding properties. Therefore, it is necessary and crucial to investigate the physical-chemical properties such as pasting and rheological properties of the rice starch with these hydrocolloids. In addition, a better understanding of the interactions of CMC and HPMC on the rice starch could provide additional tools for selection of gluten free recipes with improved rheological and textural properties.
Subject(s)
Carboxymethylcellulose Sodium/chemistry , Cellulose/analogs & derivatives , Food Additives/chemistry , Food, Formulated/analysis , Oryza/chemistry , Starch/analysis , Cellulose/chemistry , Diet, Gluten-Free , Elastic Modulus , Gels , Microscopy, Electron, Scanning , Rheology , ViscosityABSTRACT
Effects of sucrose fatty acid esters (SEs) with hydrophilic-lipophilic balance (HLB) values of 5 (S-570), 9 (S-970), and 15 (S-1570) on the pasting and rheological properties of waxy rice flour (WRF) were investigated. Rapid Visco Analyzer (RVA) showed that addition of SEs affected the pasting properties of WRF. Rheological experiment includes the steady shear flow characteristics, and dynamic viscoelastic properties were also determined using a controlled-stress rheometer. The steady shear tests demonstrated that the viscosity data fitted well with the power law model (R 2≥0.976) and all WRF pastes exhibited typical pseudoplastic and shear-thinning properties. Dynamic rheological measurements revealed that the addition of S-970 and S-1570 significantly increased the values of G' and Gâ³ of samples, whereas the addition of S-570 decreased these values. The addition of S-1570 reduced the value of tanδ, whereas S-570 and S-970 increased it.
