Physicochemical Characterization and Nutrient Assessment in Seeds of Three Species of Castanopsis (Chestnut)

Nadia, Mat (2017) Physicochemical Characterization and Nutrient Assessment in Seeds of Three Species of Castanopsis (Chestnut). Masters thesis, Universiti Malaysia Sarawak (UNIMAS).

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Abstract

Genus of Castanopsis belonging to Fagaceae family consistS" of 120 speCIes distributed throughout tropical and temperate forest of Asia. Nutrient assessment of Castanopsis sp were evaluated in this study. The chemical characterization on the Castanopsis seed oils and seed extract were also determined. Castanopsis megacarpa seeds were colle<;led from Limbang, while C. inermis and C. carlesii seeds were collected from Kuching, Sarawak. Seed samples were Soxhlet extracted using a mixture of n-hexane:dichloromethane (1: 1; v/v) for 8 hours and methylated seed oils were analyzed on Gas Chromatography-Flame Ionisation Detect 0f (GC-FID). Fiber and lipids in all seeds of three Castanopsis species in the range of 0.67­ 9.83% and 0.28-4.18%, respectively. C. megacarpa seeds can be a good source of protein as protein was highest in C. megacarpa seeds. Considerable amount of carbohydrate was showed in C. inermis seeds. Zn and Mn were detected in all Castanopis seeds in the range of 0.28-0.86 and 1.00- 2.96 mg/L, respectively, while Pb, Cd and As were not detected in any seed samples. Considerable amount of nutrients such as Ca, K and Na were detected in all seeds studied. Anti-nutrient such as oxalate and phytate were detected in all seeds studied but the amount is not harmful enough to prevent the consumption of these fruits. Palmitic acid, a-linolenic acid, oleic acid and palmitoleic acid have been identified in all seed oils studied, and these fatty acids can be considered as fingerprint for the genus of Castanopsis. ¥ajor fatty acids in C. megacarpa seed oil were palmitic acid and linolelaidic acid, while C. inermis seed oil contained high amount of linoleic acid and palmitic acid. Linoleic acid and oleic acid are major composition of C. carlesii seed oil. Non-polar fractions (CF A-CFc) of C. megacarpa seeds methanol extract contained hydrocarbons and several siloxanes. Gas Chromatography-Mass Spectrometer (GC-MS) analysis on derivatized polar fractions (CFoIII CFG) of C. megacarpa seeds methanol extracts showed additional peaks in their chromatograms compared to underivatised fractions. These additional peaks correspond to carbohydrates, alcohols and fatty acid compounds. C. megacarpa seed oil showed antioxidant properties with ECso 699.15 mg/L. Toxicity test against A. salina for seed oils showed C. megacarpa seed oil was toxic with LCso of 2.83 mg/L, while C. inermis and C. carlesii seed oils were not toxic with LCso > 100 mg/L. C. megacarpa seeds methanol e~-tract and polar combined fraction showed antioxidant properties as indicated by lower ECso «300 mg/L). Toxicity test against A. salina showed C. megacarpa seeds methanol extract and polar combined fractions were toxic with LCso <100 mg/L. This study showed all three Castanopsis seeds contain appreciable amounts of macronutrients (fiber, lipid, protein and carbohydrate), mineral elements (K, Ca, Na), low level of anti-nutrients (oxalate and phytate) and undetected toxic metals (Cd, Pb, As). High amounts of polyunsaturated fatty acids (PUF As), reasonable ratio of PUF As to saturated fatty acid and remarkable of antioxidant properties showed that Castanopsis seeds oils can be used as an important nutritional source for human consumption.

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