Effect of repeated heat-moisture treatments on digestibility, physicochemical and structural properties of sweet potato starch

Published Date
March 2016, Vol.54:202–210, doi:10.1016/j.foodhyd.2015.10.002

Title 
 Effect of repeated heat-moisture treatments on digestibility, physicochemical and structural properties of sweet potato starch

• Author 

• Ting-Ting Huang ^a
• Da-Nian Zhou ^a
• Zheng-Yu Jin ^b
• Xue-Ming Xu ^b
• Han-Qing Chen ^a,,

• aSchool of Biotechnology and Food Engineering, Hefei University of Technology, 193 Tunxi Road, Hefei 230009, Anhui, PR China
• bState Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, PR China

Received 23 April 2015. Revised 26 September 2015. Accepted 3 October 2015. Available online 22 October 2015.

Highlights

• •
  Sweet potato starch was modified by repeated heat-moisture treatments (RHMT).
• •
  The RHMT-3 starch samples had the maximum SDS content of 19.61%.
• •
  Thermo-stable SDS content reached the maximum (14.46%) by RHMT-3.
• •
  Thermal and pasting properties were significantly changed by RHMT.
• •
  RHMT changed the crystalline pattern from C_a to A type.

Abstract

In the present study, the effects of repeated heat-moisture treatments (RHMT) on the in vitro digestibility, physicochemical and structural properties of sweet potato starch were investigated. The cycling times of RHMT ranging from 1 to 5 and heat-moisture treatment for 6 h were designated as RHMT-1, RHMT-2, RHMT-3, RHMT-4, RHMT-5 and HMT-6h, respectively. The results showed that as the cycling times of RHMT increased, the SDS content of starch samples increased gradually and reached the maximum (19.61%) by RHMT for 3 times, and the thermo-stable SDS content also increased and reached the maximum (14.46%) by RHMT-3, while the swelling power and solubility decreased gradually. Compared with the native starch, the gelatinization transition temperatures of modified starch samples were significantly increased, gelatinization enthalpy and gelatinization temperature range decreased markedly. The values of degree of gelatinization (DG) showed that RHMT caused some gelatinization of the starch granules. Moreover, the RHMT starch samples exhibited significantly increased pasting temperatures, reduced viscosities, and no longer exhibited traditional pasting profiles for the lack of a true peak viscosity and no breakdown, and the agglomerations of granules were found in them. The variation in infrared absorbance ratio of 1047 cm⁻¹ and 1022 cm⁻¹ of RHMT starch samples were consistent with that in relative crystallinity, and RHMT starch samples exhibited A type crystalline pattern. These results suggested that structural changes of sweet potato starch by RHMT significantly affected the digestibility and physicochemical properties.

Graphical abstract

Keywords

• Sweet potato starch
• Slowly digestible starch
• Repeated heat-moisture treatment
• Digestibility
• Physicochemical properties
• Structural characteristics

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• ∗ 
  Corresponding author.

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