Biochemical Characterization and Multivariate Analysis of Longan (Dimocarpus longan Lour.) Varieties under Kerala Conditions
Varsha Augustine
Department of Fruit Science, College of Agriculture, Vellayani, Thiruvananthapuram, 695522, Kerala Agricultural University, Kerala, India.
B. Bindu *
Farming Systems Research Station, Kerala Agricultural University, Sadanandapuram, Kottarakkara, Kollam, 691 531, India.
S. Simi
Department of Fruit Science, College of Agriculture, Vellayani, Thiruvananthapuram, 695522, Kerala Agricultural University, Kerala, India.
B. Renjan
Krishi Vigyan Kendra, Kerala Agricultural University, Sadanandapuram, Kottarakkara, Kollam, 691 531, India.
Pratheesh P. Gopinath
Department of Agricultural Statistics, College of Agriculture, Vellayani, Thiruvananthapuram, 695522, Kerala Agricultural University, Kerala, India.
*Author to whom correspondence should be addressed.
Abstract
Longan (Dimocarpus longan Lour.) is an important fruit crop whose eating quality is associated with soluble solids, acidity, sugars and ascorbic acid. This study evaluated seven longan varieties available in Kerala—All Season, Diamond River, Edaw Star, Ping Pong, Ruby, Shogun and White—using six biochemical fruit-quality traits and multivariate analyses. Total soluble solids (TSS), titratable acidity, ascorbic acid, total sugars, reducing sugars and non-reducing sugars were assessed. TSS ranged from 16.40 to 24.97 °Brix, acidity from 0.02 to 0.63%, ascorbic acid from 57.37 to 79.16 mg 100 g−1, total sugars from 11.47 to 14.89%, reducing sugars from 4.95 to 5.99% and non-reducing sugars from 6.51 to 9.69%. Ruby recorded the highest TSS, whereas Edaw Star recorded the highest ascorbic acid, total sugar and non-reducing sugar values. Shogun recorded the highest acidity and reducing sugar content. Agglomerative hierarchical clustering separated the seven varieties into three biochemical clusters. Principal component analysis showed that PC1 and PC2 explained 38.52% and 32.66% of the total variance, respectively, accounting jointly for 71.18%. PC3 contributed a further 19.75%, increasing the cumulative variance explained to 90.93%. Reducing sugar, ascorbic acid and TSS contributed strongly to PC1, while total sugar and non-reducing sugar were important for PC2. These results demonstrate measurable biochemical variation among the evaluated longan varieties under Kerala conditions.
Keywords: Dimocarpus longan, biochemical characterisation, TSS, acidity, ascorbic acid, sugars, cluster analysis, principal component analysis