Comparative Assessment of Starter Culture-Fermented Condiments Made from Seeds of Citrullus lanatus (Watermelon)

Aim: This study was conducted to assess fermented condiments that were made from watermelon seeds, using isolated organisms from traditional fermentation as starter-cultures.

Study Design: This is a laboratory-controlled experimental design.

Place and Duration of Study: Dept. of Microbiology, Nasarawa State University, Keffi, Nigeria, between March and May 2017.

Methodology: Traditionally fermented (chance-inoculated) ‘ogiri’ condiment was made from sun-dried watermelon seeds. Microbiological isolation and identification were carried out using standard techniques, to obtain the participating organisms. Afterwards, sterilized packages of another batch of boiled, mashed and banana-leaf packaged seeds were aseptically inoculated with the pure isolates obtained earlier as starter cultures for a subsequent laboratory-controlled 3-day-fermentation process at 37°C in an incubator. All the different fermented products (produced by both uncontrolled and controlled fermentation) were subjected to proximate analysis. Also, the organoleptic quality attributes of the products were determined by conducting sensory evaluation on the various samples.

Results: The traditional fermentation of the watermelon seeds yielded an oily brownish paste, which has a strong characteristic pungent aroma. The participating organisms obtained from traditional fermentation were Bacillus subtilis, Staphylococcus saprophyticus, Corynebacterium xerosis and Lactobacillus fermenti. The result of the proximate composition show that the moisture content of the samples ranges from 3.5% to 5.4%, protein content ranges from 13.4% to 21.1%, fat content ranges from 25.5% to 40.8%, carbohydrate content of the samples ranges from 29.4% to 49.5% and the ash (total minerals) content ranges from 4.5% to 6.5%. The result of sensory evaluation generally indicated that in terms of all organoleptic attributes assessed, the combined isolates fermented sample was most preferred by the panelists.

Conclusion: It can be concluded that a laboratory prepared watermelon seed ‘ogiri’ with starter cultures of Lactobacillus fermenti, Corynebacterium xerosis and/or Bacillus subtilis can yield an organoleptically acceptable and highly proteinous condiment.