Luangsakul, Naphatrapi

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Preferred name
Luangsakul, Naphatrapi
Alternative Name
Luangsakul, N.
Naphatrapi, Luangsakul
Main Affiliation
Email
naphatrapi.lu@kmitl.ac.th

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    The effects of ultrasound – assisted recrystallization followed by chilling to produce the lower glycemic index of rice with different amylose content
    (2020-09-01)
    Kunyanee, Kannika
    ;
    Luangsakul, Naphatrapi
    White rice is a major source of carbohydrates, but its high glycemic index makes it unsuitable for diabetics. The objective of this study was to lower the expected glycemic index (eGI) of two white rice cultivars, ‘KDML105’ (low amylose content) and ‘CN1’ (high amylose content), using ultrasound, chilling treatments, or the combination of both. Ultrasound was applied by ultrasonic bath with varied amplitude and duration; chilling was performed at 4 °C for 24 h. Fourier transform infrared spectroscopy, X-ray diffraction, and gelatinization assays revealed that ultrasound treatment induced changes in grain crystallinity These changes affected the eGI, increasing it for ‘KDML105’, and lowering it for ‘CN1’. The combination of ultrasound and chilling contributed to rearrangement of starch molecules, causing a decrease in the eGI of both cultivars. Therefore, the combination of ultrasound and chilling treatment strongly promoted lowering the eGI of both rice cultivars.
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    The utilization of ultrasound and chilling treatment to reduce GI in Thai glutinous rice (RD6)
    (2018-12-01)
    Kunyanee, K.
    ;
    Luangsakul, N.
    The source of carbohydrate in the North and North-Eastern areas in Thailand are predominantly based on glutinous rice which high glycemic index (GI75-92). Lower GI glutinous rice was interesting prospect to develop diabetics. There are modified methods to reduce GI by limit the accessibility of the digestive enzymes on starch molecule. The most common physical modification method used for reducing GI on starch are hydrothermal and gelatinization-retrogradation methods. Ultrasound is the sound wave at frequency exceeding audible threshold of the human hearing rang. It is studied on starch to change the molecular structure for improving some physicochemical properties. Therefore, this resecrch focused on the utilization of ultrasound and chilling treatment to reduce GI in Thai glutinousonrice (RD6). The glutinous rice was treated with ultrasound for 15 and 30 min and amplitude at 40, 70, and 100%. All of the ultrasound-treated rice was stored at 4 <sup>o</sup> Cfor 24 h. Then, thery were analyzed on the ratio crystalline to amorphous by FTIR, thermal properties by DSC, RVA pasting properties, and GI. With increasing time and amplitude of ultrasound, the ratio of crystalline to amorphous decreased from 0.779 to 0.662. The onset temperatureand enthalpy (∆H) decreased from 62.38 to 58.10 <sup>o</sup> C, and 1.81 to 0.70 J/g, respectively. The peak viscosity, and final viscosity from RVA increased from 3079 to 3838.67 cP and 2407.33 to 2922 cP, respectively. When increasing time and amplitude of ultrasound, the hydrolysis index (HI) and eGI slightly increased with longer time and higher amplitude than the others. The chilled samplesafter ultrasound treatment showed that the ratio of crystalline to amorphous, and ∆H increased while HI and eGI decreased when compared to unchilled ultrasound treated rice.