Physical and chemical properties of starfruit (Averrhoa Carambola L. cv. Bintang Mas) at different maturity indexes

Abstract

Bintang Mas is a new variant of starfruit (Averrhoa Carambola L.) developed by Malaysian Agricultural Research and Development Institute (MARDI) in 2019. This study determined the physical properties (length, diameter, width of ridge, weight, volume, and density) and chemical properties (oxalic acid, malic acid, reducing sugar, moisture content, vitamin C, carbohydrate, crude fiber, protein, ash, and fat) between maturity stages (index 2, 4 and 6) of Bintang Mas and compared the results with export-graded starfruit variant, B10. Bintang Mas had an oblong shape while B10 had an ovoid shape, larger width of ridge, diameter, weight and volume. Partial Least Squares Regression Discriminant Analysis (PLS-DA) revealed that all physical attributes except length were not influenced by the index changes for Bintang Mas. This would improve the uniformity of the fruit size which enhances the product’s quality during grading regardless of indexes. The average reading of oxalic acid for Bintang Mas was significantly lower (60.01 mg/kg) at all maturity indexes compared to B10 (1346.67 mg/kg). PLS-DA confirmed that the main chemical attributes found in Bintang Mas were malic acid, protein, and fat content while oxalic acid and vitamin C were most profound in B10. Since oxalic acid is deleterious to human health, Bintang Mas was recommended for consumers as it contains lower oxalic acid. Meanwhile, malic acid, protein and fat content of Bintang Mas was the highest at index 4, favorable to foster good health. Early index of Bintang Mas was also preferred for exports especially to distant regions given its higher firmness and smaller diameter and ridges, which could assist in reducing the rate of spoilage and prolonging the fruit’s shelf-life.