Pickling as a preservation technique for African eggplant (Solanum aethiopicum)
Abstract
This study aimed at evaluating the potential of pickling in improving the stability of Solanum
aethiopicum. Solanum aethiopicum Shum is a member of the Solanacae family and is also known
as the African eggplant (English) and nakati (luganda). The crop is consumed as a green leafy
vegetable in Uganda and is one of the vegetables of importance in the country. The vegetables
were prepared by de-stemming, sorting, thoroughly washing them with potable water and cutting
into small pieces then mixing them with salt and sugar. The vegetables were fermented in brine
with 3%salt and 2%sugar in closed glass jars at room temperature for 14 days. The fermentation
process was monitored at 0, 2, 6, 8, 12 and 14 days by enumerating LAB, coliforms and yeasts and
molds as well as measuring the pH of the brine. Sensory evaluation (n=30 panelists) was carried
out to assess the acceptability of the pickled vegetable and determine the preference between the
fresh and pickled vegetables. The shelf stability was determined by enumerating coliforms and
yeasts and molds at 1, 2 and 3 weeks of storage.
LAB counts increased from 2.06 log cfu/ml to a maximum 8.23 log cfu/ml during fermentation.
Coliforms and fungi reduced from 5.49 log cfu/ml and 1.49 log cfu/ml respectively to undetectable
levels within 8 and 6 days of fermentation respectively. A pH value 3.35±0.01 of the brine was
achieved after 14 days of fermentation. Pickling significantly (p < 0.05) reduced the acceptability
scores of Solanum aethiopicum. The pickled vegetables had acceptability scores ranging from 5
(neither like nor disliked) to 6 (like slightly). Fresh vegetables were preferred to the pickled ones
by 70% of the panelists. The pickled vegetables were stable during the three weeks of storage.
Although pickling reduced the overall acceptability of Solanum aethiopicum from moderate liking
to neither like nor dislike, it can be applied to improve its shelf stability.