Kittipongpatana Nisit, Wiriyacharee Pairote, Phongphisutthinant Rewat, Chaipoot Supakit, Somjai Chalermkwan, Kittipongpatana Ornanong S
Department of Pharmaceutical Sciences, Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand.
Research Center for Agricultural Innovation, Chiang Mai University, Chiang Mai 50200, Thailand.
Molecules. 2021 Jun 4;26(11):3405. doi: 10.3390/molecules26113405.
A large quantity of longan fruits ( Lour.) produced annually are processed into many products, one of which is black longan, from which the dried, dark-brown meat has been used medicinally in traditional medicine, while the starch-containing seeds are discarded. In this study, starch samples (BLGSs) were isolated from seeds of black longan fruits prepared using varied conditions. The in vitro digestibility was determined in comparison with those extracted from fresh (FLGS) and dried (DLGS) seeds. Scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy were employed to evaluate the starch properties. The results showed that the yields of FLGS, DLGS, and BLGSs were 20%, 23%, and 16-22% /, respectively. SEM images showed starch granules of mixed shapes, with sizes up to 15 µm in all samples. XRD patterns confirmed an A-type crystallinity for FLGS and DLGS, with strong refraction peaks at 2θ = 15°, 17°, 18°, and 23°, while BLGSs also showed detectable peaks at 2θ = 10° and 21°, which suggested V-type structures. Thermal properties corroborated the changes by showing increases in peak gelatinization temperature (T) and enthalpy energy (ΔH) in BLGSs. The paste viscosity of BLGSs (5% /) decreased by 20-58% from that of FLGS. The FTIR peak ratio at 1045/1022 and 1022/995 cm also indicated an increase in ordered structure in BLGSs compared to FLGS. The significant increase in the amounts of slowly digestible starch (SDS) and resistant starch (RS) in BLGSs compared to FLGS, especially at a prolonged incubation time of 20 (4.2×) and 30 days (4.1×), was proposed to be due to the heat-induced formation of starch inclusion with other components inside the seed during the black longan production process. Thus, black longan seed could be a new source of starch, with increased RS content, for potential use in the food and related industries.
每年生产的大量龙眼果实（Lour.）被加工成多种产品，其中之一是黑龙眼，其深褐色的干燥果肉在传统医学中被用作药物，而含淀粉的种子则被丢弃。在本研究中，从采用不同条件制备的黑龙眼果实种子中分离出淀粉样品（BLGSs）。与从新鲜（FLGS）和干燥（DLGS）种子中提取的淀粉相比，测定了其体外消化率。采用扫描电子显微镜（SEM）、X射线衍射（XRD）、差示扫描量热法（DSC）和傅里叶变换红外（FTIR）光谱法对淀粉性质进行了评估。结果表明，FLGS、DLGS和BLGSs的得率分别为20%、23%和16 - 22%。SEM图像显示所有样品中的淀粉颗粒形状混合，尺寸可达15 µm。XRD图谱证实FLGS和DLGS为A型结晶度，在2θ = 15°、17°、18°和23°处有强折射峰，而BLGSs在2θ = 10°和21°处也显示出可检测到的峰，这表明其为V型结构。热性质通过显示BLGSs中峰值糊化温度（T）和焓能（ΔH）的增加证实了这些变化。BLGSs（5%）的糊化粘度比FLGS降低了20 - 58%。1045/1022和1022/995 cm处的FTIR峰比也表明，与FLGS相比，BLGSs的有序结构增加。与FLGS相比，BLGSs中慢消化淀粉（SDS）和抗性淀粉（RS）的含量显著增加，尤其是在延长培养时间20天（4.2倍）和30天（4.1倍）时，这被认为是由于在黑龙眼生产过程中种子内部淀粉与其他成分因热诱导形成了包合物。因此，黑龙眼种子可能是一种新的淀粉来源，其RS含量增加，可潜在用于食品及相关行业。
