Characterization of Morphological and Quality Characteristics of New Papaya (Carica papaya L) Hybrids Developed at JKUAT

Abstract

The issue of accessing high quality nutritious foods such as fruits is a major challenge for many African people. Papaya (Carica papaya L.) is among the most grown fruit crops worldwide with high economical and nutritional value. It is grown for a variety of products including juice, wine, jams, candies and dried fruits. Papaya is a very wholesome fruit and an excellent source of vitamins A and C. In Kenya, the papaya industry relies heavily on imported varieties and farmers’ selected seeds whose quality is not known. Researchers at Jomo Kenyatta University of Agriculture and Technology (JKUAT) recently developed promising papaya hybrids (lines 1, 2, 3, 4, 5, 6, 7 and 8). However, their morphological and quality characteristics have not been evaluated. Thus the main objective of this study was to evaluate the morphological, nutritional and organoleptic properties of the newly developed JKUAT papaya hybrids fruits. The morphological traits (fruits weight, fruits length, fruits diameter, internal cavity diameter, internal cavity shape, skin colour, flesh colour and stalk end fruit shape), fruits shelf life, physicochemical (pH, total soluble solid, titratable acid and total soluble solid/titratable acid ratio), vitamins (ascorbic acid and β carotene) and organoleptic test were evaluated. The mature fruits of eight newly developed papaya hybrids and their control, Sunrise Solo were evaluated using descriptor for papaya, International Board for plant Genetic Resources (IBPGR), Royal horticulture colour chart, Codex standard for fresh papaya fruits (Codex Stan 183-1993), the standard AOAC methods and the 9- point hedonic scale. The results demonstrated significant differences in fruit size among the newly developed papaya hybrid lines and the control. Line 4 had the longest and heaviest fruits. Fruits from Sunrise Solo, lines 2, 3, 7 and 8 ranged from small ( ≤ 500g) to medium in size (>500g ≤ 1000g), while those of lines 4 and 6 were large (> 1000g ≤ 3000g). Line 1 had the shortest shelf life of 4 days while Line 7 had the longest shelf life of 11 days. There was significant difference (P< 0.05) in physicochemical and vitamins content among the new papaya hybrids and Sunrise Solo. The total soluble solids (TSS) varied from 7.4 in line 8 to 12.3°Brix in lines 5 and 7. The maximum Vitamin C content of 131.63 mg/100g was recorded in line 6 while the minimum of 51 mg/100g was recorded in line 8. Vitamin A content ranged from 1.69mg/100g to 3.39 mg/100g. Lines 2,7,5,1 and Sunrise Solo were best preferred in the overall acceptability rating as the most liked, thus were promising for fresh consumption compared to line 8 which was the least liked. Hence, most newly developed papaya hybrid lines had quality traits which were comparable to or even superior to Sunrise Solo, which implies that they may be suitable for both local and export markets. The findings of this study indicate that newly developed papaya hybrid lines have fruits with superior vitamins content than Sunrise Solo. The study suggests that the newly developed papaya hybrid fruits possess excellent levels of ascorbic acid and β-carotene. Therefore, consumer education on the nutritional benefits of papaya consumption could eventually contribute to increased consumption of papaya. The findings of this study will also assist breeders in selecting the best performing papaya hybrids for commercialization and for further quality improvement. All the new papaya hybrid lines should be evaluated in different agro-ecological zones to establish the influences of different ecological conditions on their morphological and quality characteristics.