Additives increase organic acid content and improves aroma of fermented castor seeds

What is it about?

Previous studies had indicated that 2% sodium chloride and 3% lime could be used to produce acceptable fermented products from castor bean seeds. Organic acids are produced when Bacillus subtilis is used as a monoculture for the fermentation of castor oil bean seeds (Ricinus communis). The identified organic acids were oxalic, citric, tartaric, malic, succinic, lactic, formic, acetic, propionic and butyric acids. For the substrate which contained no additives (i.e without NaCl and Lime) lactic acid content increased from 0.775µg/mL at 0 h fermentation to 1.336µg/mL after 96 h. The build-up of organic acids was slower in samples containing NaCl and Lime as additives than in the naturally fermented samples. Lime provides an acidic environment which inhibits the growth of microorganisms that cannot grow well in acidic media. Sodium chloride also limits the concentration of microorganisms by preventing the growth of microbes that do not thrive in a salty medium. Both lime and sodium chloride are used in traditional food preservation. Addition of lime to fermenting castor oil bean seeds caused a continuous increase of lactic acid content (within the four-day fermentation period under study) The lactic acid content of the sample which did not contain lime or lactic acid) decreased initially and then increased as the fermentation period progressed. The value at 96 h fermentation was 1.336µg/mL as against 0.775µg/mL at the initial time of fermentation. Sample B3 (which contained 3% lime) had lactic acid content that increased as fermentation period increased with lactic acid concentration of 1.298µg/mL at 96 h fermentation. The acetic acid content of this sample increased as fermentation progressed and at 96 h fermentation, its value was 1.204µg/mL while those samples containing 2% sodium chloride (B2) and and 3% lime (B3) were 0.677µg/mL and 1.401µg/mL respectively. Sufficient organic acids were detected in the three Bacillus fermented castor oil bean samples. The production of organic acids is undoubtedly the determining factor on which the shelf life and the safety of the final product depend while the inhibition of pathogenic and spoilage flora is also dependent on a rapid and adequate formation of these organic acids. The results of amino acid analysis indicated a high concentration of all amino acids especially at 96 h of fermentation. Amino acids are known to play a major role in the taste and flavour development of foods Thus the flavour and aroma of ogiri may be due to the production of amino acids, especially glutamic acid during the fermentation process. The result of this study shows that 3% lime promoted the production of organic acids in the fermented product suggesting a superior preservative effect while the amino acids increased as fermentation progressed. The addition of 2% NaCl and 3% Lime to the fermenting product could also be a simple and practical way of extending the shelf-life of ogiri from castor oil bean and also improving aroma of food. The additives (2% NaCl and 3% Lime) add variety to the condiment types thereby increasing the number of products and market differentiation. The products can also serve as a suitable substitute for many of the imported flavouring agents in Nigeria.Amino acid profile and organic acid production were monitored during the fermentation of castor bean seeds containing Sodium Chloride and lime as additives. Addition of 3% lime led to production of highest amounts of acetic acid, butyric acid, citric acid and formic acid. the essential amino acid profile of the product also increased.

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Photo by Nik Ramzi Nik Hassan on Unsplash

Photo by Nik Ramzi Nik Hassan on Unsplash

Why is it important?

Use of odium Chloride and lime as additives improves the nutrient quality of fermented castor bean seeds. Essential amino acids content increases and organic acids that influence aroma are produced.

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