Effect of harvesting stage on postharvest quality of black pepper piper nigrum l. cultivars grown in Morogoro, Tanzania

Abstract

Optimal harvest maturity stage determines the on-shelf quality of black pepper (Piper nigrum L.). Small-scale farmers in Morogoro harvest black pepper before reaching full maturity to catch up with high market prices offered early in the season. Unfortunately, traders are complaining on the quality of black pepper from the area. This study evaluated the effect of harvesting stages on post-harvest quality of pepper cultivars grown in the Morogoro district. Pepper cultivars; Babu kati, Babu kubwa, and Ismailia at premature and mature stages were dried on coconut leaves mats to suitable drying stage. Treatments in a 2 x 3 factorial experiment following a complete randomized design (CRD) were replicated thrice. Statistical significance of variables was generated by ANOVA and mean separation by Tukey HSD test at p ≤ 0.05. Results showed a significant (p<0.001) difference between harvest stages and cultivars on berry colour, moisture content, berry firmness, dry recover and weight loss percentage. Pepper berries at pre-mature stage across cultivars had higher (79.11%) initial moisture content than mature berries (71.6%). Mature berries had higher dry recovery percentage (28.84%) than pre mature (15.78%). Mature “Ismailia” berries had the highest firmness (10.5kg/mm2) than premature (5.8 kg/mm2). During sun drying, colour values L*(brightness), and b* (yellowness) decreased significantly while greenness decreased as a* values increased from more negative values to zero in both harvesting stages as pepper berries darkened. Colour changes were sharper on mature than pre-mature harvested pepper corns. These findings will help farmers to make right decision on when to harvest for quality black pepper product. Farmers are recommended to harvest black pepper when mature for better firmness and colour development during drying. Further studies are required to determine the sensory quality and volatile oil contents of the cultivars when harvested premature and mature stages.