Assessment of the Physical, Chemical, and Organoleptic Characteristics of Watermelon (Citrullus lanatus) Waxed with Different Plant Oils

Abstract

The study was conducted in two phases. Phase 1 was to assess the handling and management of watermelon along the value chain in the Ada-East district of Ghana. One hundred open and close ended questionnaires were administered to farmers and dealers of watermelon. From the study, it was observed that the value chain of watermelon starts from land preparation and ends at the point it gets to the final consumer. The key players along the chain were identified to be farmers, dealers (transporters and sellers i.e. both whole sellers and retailers) and consumers. The losses incurred started on the farm especially during husbandry operations and harvesting. Losses also occurred during loading/off-loading activities (0.45%) and vehicular transportation (0.93%). Additionally, inappropriate storage conditions also resulted in some losses. The main causes of the losses in the value chain were seen to be attack by disease causing organisms, insect pest attack, dropping and cracking of fruits, thieves and materials used to cover fruits during transportation. The total losses before harvest were estimated to be GHȻ 31,649.00 per season whiles total losses during and after harvest was projected to stand at GHȻ 69,825.00 per season. It was therefore recommended that farmers pay a particular attention to the onset of diseases and take quick measures such as immediate use of fungicides as well as the physical removal of affected fruits. Extra care should be taken when handling fruits especially during loading and off-loading operations. Vehicles used in transporting watermelon fruits should be types that are designed for carrying agricultural goods. These may include trucks with cooling systems and cushioning materials that mitigates the forces of impact; responsible for causing internal injury and cracks. Phase 2 was to assess the effect of different plant oils used as waxing material on the physical, chemical and organoleptic characteristics of watermelon following length of storage. Watermelons were waxed with different plant oils and stored for 21 days. The experiment was a full factorial experiment laid out in completely randomized design (CRD) with 5 replicates. The study revealed that the waxing mixtures containing Neem oil with Shea-butter (NSBW) and Neem oil with Palm oil (NPW) were not able to prolong the storage life of watermelon. However, the mixture containing 4% Neem oil and 96% Coconut oil [NCW (4:96)] was able to prolong the storage life and reduce percent total weight loss (%TWL) of watermelon by decreasing rate of respiration. Neem oil with Coconut oil treatments (NCW treatments) also retained the vitamin C content of fruits better than non-waxed fruits especially when waxed with NCW (1:99), NCW (2:98) and NCW (3:97). Additionally, NCW did not affect some organoleptic and chemical properties such as attractiveness, flavour (smell/aroma), glossiness, mouth feel, taste, overall acceptability and Total Titrable Acids (TTA). NCW (3:97) also retains % brix better than any of the NCW treatments. It was also put forward that, long term storage of watermelon without NCW waxing reduced some organoleptic properties and created undesirable chemical and physical properties. It was therefore recommended that NCW be considered as a possible watermelon waxing material in prolonging the storage life of watermelon as well as maintaining its physical, chemical and organoleptic properties. Additionally, it was advised that the use of Shea-butter and palm oil should not be considered in the future for waxing watermelon.