Hygiene Practices Of Vendors And Quality Of Grasshopper (Ruspolia Differens) Products Sold In Open Markets Of Uganda

Abstract

The edible grasshopper, Ruspolia differens Serville locally known as “Nsenene” is a major delicacy in Uganda, providing food and income to many households. Grasshoppers are harvested from the wild, mainly in the Central and Western parts of Uganda and transported to urban markets for processing and sale. Both fresh and cooked grasshoppers are processed and sold along the streets, in open air environments that make them prone to contamination. The aim of this study was to investigate the characteristics of the grasshopper vendors, the microbial status of the marketed grasshoppers and to conduct a shelf life study of boiled and dried grasshoppers. In the first objective, cross-sectional data on vendor characteristics were collected from 74 grasshopper vendors, in 12 major markets in Kampala and Masaka districts of Uganda. For the second objective, 25 samples of fresh, deep-fried and boiled grasshoppers sold by the respective vendors were collected for microbial analysis using standard plating techniques and molecular tools. As the third objective, an additional 3kg of raw unprocessed grasshoppers was obtained from vendors and these were boiled for 10, 15 and 20 minutes and further oven and sun-dried. The samples were then packaged in Kraft paper bags with a viewing window and their shelf life monitored against the following parameters: Total viable counts (TVC), oxidative rancidity and sensory characteristics. Our research findings showed that 62% of the vendors were mobile street vendors while 38% were stationary market vendors. Of these, 68% of the vendors were women, half of whom had studied up to primary school level. Furthermore, 85% of the vendors did not have a public health food handler‟s certificate. Vendors also scored poorly on personal and food hygiene practices examined (48 and 52% for street and market vendors, respectively) Microbial analysis of marketed grasshoppers (raw, deep-fried and boiled) showed high counts of total aerobic bacterial load (4.3-9.5 Log cfu/g), Enterobacteriaceae (4.6-9.3 Log cfu/g) and xiii yeasts and molds (3.5-7.9 Log cfu/g). These levels were above the acceptable limits for ready-to-eat marketed foods which stand at < 5 logcfu/g. Molecular characterization of bacteria and fungi colonies isolated from the grasshoppers revealed 7 pathogenic species of bacteria, 3 of which are known pathogens capable of causing illness in otherwise healthy individuals, (Bacillus cereus, Staphylococcus aureus, Staphylococcus haemolyticus). In addition 2 types of mycotoxin producing mold were isolated and these included Aspergillus fumigatus and Aspergillus neobridgeri. These results confirm that there is a risk of foodborne illness after consuming grasshoppers from the streets of Uganda. For the shelf life study, results show that boiling for 10, 15 and 20 minutes was sufficient to reduce the TVC load to undetectable levels. Accelerated shelf life analysis for 6 days at 55ºC showed that the sample boiled for 20 minutes and oven-dried had a significantly (p<0.05) better microbial quality, with a plate count of < 5 log cfu/g up to the 5th day. The Thiobarbituric acid test results showed high lipid oxidation of >1.0 mg MDA/kg of grasshoppers after day 1 of storage. Sensory scores for odour, appearance and general acceptability had mean scores of 4.48±1.446, 4.03±1.464, and 4.31±1.400 respectively, indicating that the panelists neither liked nor disliked the samples during the course of storage. These findings demonstrate that boiling for 20 minutes and oven drying is the most preferred processing method to ensure microbial safety of grasshoppers for up to an equivalent of approximately 6 months. In conclusion, there is a dire need for improvement of the microbial quality of processed and unprocessed R. differens grasshoppers marketed in Uganda. This study recommends the training of grasshopper vendors on good food hygiene practices as well as on optimum processing techniques and the creation of specific local and national policies as well as regulations that governs food safety in the edible “nsenene” subsector in order to provide safe insect-based food products to consumers.