STUDIES ON THE THERMAL PROPERTIES, LYCOPENE AND ΒETA-CAROTENE CONTENTS OF PUMPKIN FRUIT FLOUR

The pumpkin plant (Cucurbita pepo) is a vital crop that has potential to significantly contribute to food sustainability, particularly in Nigeria and other tropical countries. Its rich carotenoids and essential nutrients often decrease during processing, underscoring the need for further exploration in this field. This study then examined the effects of pretreatment techniques (blanching and brining), and drying methods (oven and sun-drying), on the preservation of lycopene and beta carotene in pumpkin fruit flour, and to determine its thermal properties that would enhance its usage during food formulation. All investigations were carried out using standard procedures. The results showed that the blanched samples exhibited a lower phase transition temperature range (370-375°C) than the control (unblanched) samples (330-395°C). Brined samples had the highest phase transition temperature ranges (395-410°C). For sun-drying (and oven drying), the densities, thermal conductivities, heat transfer coefficients, specific heat capacities and thermal diffusivities of the control (unblanched), blanched and brined samples are 1.0186 (1.10143)g/ml, 0.5905(0.5918)g/ml, 0.4764 (0.70646)g/ml; 0.0461(0.0527)W/mK, 0.0307(0.0307)W/mK, 0.3687(0.1844)W/mK; 3.8409(4.3896)W/m².K, 2.5606(2.5606)W/m². K, 30.7272 (15.3636)W/m². K; 0.0061(0.0061)J/kg.°C, 0.0054(0.0067)J/kg.°C, 0.0739(0.0232)J/kg.°C; and 7.3745 (8.5389)m²/s, 9.7033(7.7626)m²/s, 10.4796(11.2558)m²/s respectively. The lycopene and beta-carotenoids content after sun-drying (and oven drying) for control (unblanched), blanched and brined samples are: 10.32(9.72)mg/100g, 9.73(9.95)mg/100g, 10.64(10.18)mg/100g and 34.13(41.68)mg/100g, 37.25(37.47)mg/100g, 32.78(39.58)mg/100g respectively. Controlled oven drying retained more lycopene and beta carotene than sun drying, and blanching had no significant effect on beta carotene levels.