สมบัติทางกายภาพ สมบัติทางเคมีและคุณสมบัติการต้านอนุมูลอิสระที่มีผลมาจากระยะการเจริญของผลและการอบแห้งแบบลมร้อนของส้มควาย (Garcinia pedunculata) และส้มแขก (Garcinia atroviridis)

Abstract

Somkhwai (Garcinia pedunculata Roxb., G. pedunculata) and Somkhaek (G. atroviridis Griffith ex T. Anderson., G. atroviridis) are Thai medicinal plants found most in the southern area of Thailand. This research aimed to study (1) growth developmental stages on the physical, chemical and antioxidant properties of Somkhwai and Somkhaek fruits. and (2) hot- air dehydration time on the physical, chemical and antioxidant properties of Somkhwai and Somkhaek slices. It was found that Somkhwai and Somkhaek fruits from the 5 developmental stage (maturity stage) had the firmness of 11.47±1.71 N and 7.64±0.33 N, and hue angle (h) of 84.03±2.31 degree and 92.54±1.13 degree, respectively, which both values were significantly (p<0.05) lower than those of other stages. The Somkhwai fruit at this stage also contained highest in the total phenolic content (TPC) of 5.34±0.10 mg GAE/g (db) and DPPH scavenging activity of 0.53±0.07 μg/ml. Also, the contents of hydroxycitric acid (HCA) and hydroxycitric acid lactone (HCAL) were 531.26±4.49 and 396.79±4.30 mg/g (db), respectively. Whereas the Somkhaek fruit from the 5th maturity stage contained both TPC of 1.50±0.09 mg GAE/g (db) and DPPH scavenging activity of 0.91±0.10 mg/ml, gradually lower than those of the 1 maturity stage. While the contents of HCA and HCAL were 348.19±1.70 and 199.20±0.89 mg/g (db), respectively. In addition, the hot-air drying at 51°C of each stage of Somkhwai and Somkhaek slices (1.0 mm average thickness) until obtaining the final moisture content of proximately 9% was performed. During dehydration, drying rates of both Somkhwai and Somkhaek slices from each maturity stage showed changes in similar trends with increasing in the rate during 0 to 4 hours and decreasing during 4 to 8 hours except Somkhwai slices from the 3rd maturity stage had quite constant in the dryings rate at the beginning of 4 hours and great reduction in the later of 4 hours. It was found that the maturity stage of fruits significantly effected (p<0.05) on the cutting force, color values, TA, TPC and DPPH scavenging activity. Somkhwai and Somkhaek slices during dehydration had the moisture contents great tentatively reduction in every maturity stage at drying time of 4 hours. And at the dehydration time of 8 hours, it was found that dried Somkhwai slices from the 5th maturity stage had the least of h value. Which were in the range from 45 to 90 degree, while the cutting force was the least of 37.20 N. Furthermore, dried Somkhaek slices from the 5" maturity stage had the greatest in cutting force of 42.81 N and C* higher than those of other stage dried ones. Also, the least h value was in the range of 90 to 135 degree. As the dehydration times of both Somkhwai and Somkhaek slices from each maturity stage increased, the TPC and DPPH scavenging activity trended to significantly reduce. Moreover, the correlation number (r) of TPC and DPPH scavenging activity (EC) of dried Somkhwai and Somkhaek slices were -0.531 and -0.247, respectively. It was also found that hot-air dehydration effected on the reduction in contents of HCA and HCAL of dried Somkhwai slices obtaining from the maturity stage of 4" and 5". At the end of dehydration process of 8 hours, it was found that dried Somkhwai slices from both maturity stages contained HCA and HCAL of 254.39±1.06 and 221.63±1.26 mg/g (db), and of 222.06±0.30 and 196.55±0.61 mg/g (db), respectively. Dried Somkhaek slices from the 4th maturity stage had the decrease in HCA and HCAL contents of 160.41±0.45 and 111.46±0.46 mg/g (db), respectively. While the observed dried Somkhaek slices from the 5" maturity stage contained greater in HCA and HCAL contents of 398.60±0.80 and 270.86±3.11 mg/g (db), respectively. This research showed that fresh Somkhwai fruit from the 5 maturity stage provided the highest in the contents of TPC, DPPH scavenging activity, HCA and HCAL. Whereas fresh Somkhaek fruit from the 5th maturity had highest only HCA and HCAL contents. While dried Somkhwai slices from the 5" maturity stage at drying time of 8 hours had decrease in contents of both hydroxycitric and hydroxycitric lactone. However, dried Somkhaek slices from the same maturity stage and drying time had greater in both amounts of two compounds.