Effect of heat-moisture treatment on the structural and physicochemical characteristics of sand rice (Agriophyllum squarrosum) starch

A small granule starch from sand rice (Agriophyllum squarrosum) was subjected to heat-moisture treatment (HMT) at different moisture contents (MCs,15%-30%). With MC≤20%, a higher MC resulted in increases in the starch orders (i.e., short-range and crystalline structure) with unchanged granule morphology. Nonetheless, a further elevated MC (>20%) gradually destroyed the granule morphology and starch orders. Also, HMT gradually vanished the lamellar structure as MC increased during HMT. These structural evolutions in HMT-modified starch resulted in greater thermal stability, higher pasting temperature, lower pasting viscosity and weakened digestibility. Particularly, HMT applied directly in sand rice starch at 20% MC obtained the highest amount of SDS and RS (23.6%), which was 2.2-fold higher than that of native starch. Therefore, the small granule sand rice starch can be modulated by HMT through controlled MC to expand their application range in food production.

Carioca bean starch upon synergic modification: characteristics and films properties

BACKGROUND

The use of damaged beans for starch isolation comprises an end-use alternative for a product that is not accepted by the consumer. For that reason, isolation and modification of Carioca bean starch should be explored and evaluated as a suitable source for biodegradable material. The present study aimed to evaluate the synergism of physical and chemical modifications on Carioca bean starch with respect to improving the properties of biodegradable films. A heat-moisture treatment (HMT) followed by oxidation by sodium hypochlorite was performed and vice versa.

RESULTS

Synergism was noted in the starch properties compared to the single modification. When the oxidation was applied first, a higher amylose and carbonyl content was noted. HMT, isolated and as a second modification, caused a more pronounced effect on viscosity profile than the oxidized starch, with an increase in paste temperature and a decrease in viscosity, breakdown and final viscosity.

CONCLUSION

The results obtained in the present study reflect a decrease in water vapor permeability, although a higher tensile strength was noted when oxidation was applied, as a single and as a first modification. © 2020 Society of Chemical Industry.

In vitro digestibility of hydrothermally modified Bambara groundnut (Vigna subterranean L.) starch and flour

In-vitro digestibility and functional properties of Bambara groundnut (Vigna subterranean) (BG) flour, and its native and hydrothermally modified starches were investigated. The isolated native starch (BNS) was modified by annealing at 50°C for 48 hr (BAS), and heat-moisture treated at 100°C for 16 hr at 25% moisture level (BHS). The crude protein of BG flour was 16.88%. The amylose content of the flour and native starch was 6.10% and 27.70%, respectively. Hydrothermal modification increased the gelatinization profile of the starch but reduces its pasting properties. Swelling and solubility of the flour and starches increased with increase in temperature. X-ray diffraction revealed BNS and BAS exhibited "Type C" crystallinity pattern while BHS was "Type A." The BNS granule was oval, its diameter between 22 and 30 μm, with no significant change in the morphology of BAS and BHS. The BG flour had 33% resistant starch and 11.63% digestible starch. Heat-moisture treatment enhanced the resistant starch content of the native starch significantly.