Fermented pickle production from water hyacinth (Eichhornia crassipes Solms) stem

Water hyacinth (Eichhornia crassipes Solms) is a free-floating aquatic species widely distributed on rivers, canals and estuaries. It propagated quickly and extensively in a short period. This caused some obstacles for river traffic. This plant was utilized for the production of handicrafts, fertilizer, animal feed, and biofuel in the agro-industry. People also consumed the young stem of this plant as a natural vegetable food in cuisine due to its palatable taste. Pickling was well-known as one of the most ancient gastronomic professions to store food under acidic conditions for a long period of time in an ambient environment. This research evaluated the pickle production from the young stems of water hyacinth. Different technical parameters of the pickling process such as effect starter culture strains (Lactobacillus delbrueckii, Lactobacillus plantarum, Lactobacillus acidophilus and Saccharomyces cerevisiae) with different inoculum ratios (5-25 mL of 109 CFU/mL starter culture), brine solutions (250 ppm of potassium chloride, calcium chloride, calcium acetate, magnesium chloride, aluminum chloride combined with 5% of sodium chloride), sugar content (2-4%) and fermentation time (0-10 days) were thoroughly examined. Firmness (N), total acidity (%), total phenolic content (mg GAE/100 g dry weight), total antioxidant capacity (mg AAE/g dry weight) and sensory score were measured to define the optimal species of starter culture, ratio of starter culture, brine solution, sugar content and fermentation time. Results showed that young water hyacinth stems should be fermented with 20 mL of 109 CFU/mL L. plantarum with 5% sodium chloride, combined with 250 ppm of calcium chloride, 3% sugar supplementation and 6 days of fermentation. Pickle of young water hyacinth stem maintained the highest texture firmness (11.86±0.03 N), total acidity (1.50±0.01%), total phenolic content (61.07±0.04 mg GAE/100 g dry weight), total antioxidant capacity (7.79±0.02 mg AAE/g dry weight) and sensory score (8.91±0.03). The added value of water hyacinth could be highly exploited from this research.