Effect of Selected Environmental Parameters on Quality of Syzygium Cuminii Fruits in Kenya

Abstract

Syzygium cuminii tree species belongs to the Myrtaceae family. The problem of underutilization of indigenous and traditional food resources can be addressed by promoting the utilization of these fruits to strengthen the food availability and adequacy systems in Kenya. This research investigated the effect of selected environmental parameters namely; temperature, rainfall, sunshine, relative humidity and soil types on the quality of the Syzygium fruits. The parameters studied include fruit size, moisture content, color, pH, Total Soluble Solids, Titratable acidity, minerals, vitamin C, crude proteins, crude fat and fibre, carbohydrates and energy. Analysis was done using standard methodologies including use of an Inductively Coupled Plasma – Optical emission Spectrometer for elemental analysis and High Pressure Liquid Chromatography for the determination of Vitamin C that ranged between 76.55 ± 0.02 and 965.24 ± 0.21 mg/100 g. There was a significant difference at P = .05 in ash content with Kwale recording a mean value of 2.74± 0.01 Vis avis 1.61 ±0.02 percent from Bungoma. There was a positive correlation between TSS with fruit Maturity. Soil pH, Na, Mn, and Zn were significantly different between the two counties, P = 0.05. Soil porosity highly influenced soil pH, while particle density caused an increase in bulk density, which in turn increased fruit weight, fruit pH, and ash content. Five out of 12 models with P = 0.05 were used to predict the dependent variables; Model 3 can predict ascorbic acid with the highest accuracy at R2 = 0 .93, 5, crude protein, R2 = 0.87, 6, Zinc, R2 = 0.98, 9, ascorbic acid, R2 =0.99 and 12, Zinc, R2 = 0.99. The quality of fruits was affected by the tree canopy orientation with fruits oriented towards the east developed higher TSS, Vitamin C content and intense color. Higher annual rainfall of 1700 mm in Bungoma compared to 1032 mm in Kwale resulted in low Total Soluble Solids of 14.27 ± 0.01 to 15.05 ± 0.18 and high Titratable acidity, 0.74 ± 0.01 – 0.78 ± 0.02 for over 51 percent of the fruits that were analyzed. Fruits obtained from Kwale at low altitude, 162 ± 7 m had better quality than those from Bungoma at higher altitude, 1612 ± 18 m. Although the brix content and pH of fresh fruit varied with the prepared juice, no significant difference relating to abiotic factors was observed. The results of this revealed that Syzygium cuminii fruit is rich in most of the dietary macro and micro elements such as Vitamin C, needed for health, and the fruits can be used for establishing small and medium enterprises. Hence, there should be increase in efforts to provide the much needed resource base for product development, value addition and development of organic fruit juices.