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Received: 16 January, 2017
Received in revised form: 1 July, 2017
Accepted: 21 November, 2018
Keywords
Aspergillus Niger
Castor
Food Spoilage
Seed-Borne Fungi
Ricinine.
Abstract
Aspergillus niger is the most common fungus causing food spoilage and bio-deterioration. It is also a type of seed-borne fungus that can lower the seed viability. A. niger is very fast growing and difficult to control. Usually, fungicides are used to protect plants from fungal attacks. In the present work, the potential use of the methanolic extract of castor (Ricinus communis L.) leaves as a natural antifungal compound against A. niger isolated from stored groundnuts was investigated. The bioactive compound was also determined by gas chromatography-mass spectroscopy (GC-MS). Extraction of castor leaves was done by maceration using methanol as solvent. The yield of the extract was 10.64%. The antimicrobial activity against A. niger was determined by biomass growth inhibition test. The results showed that the extract at 500 pg/mL inhibited the fungal growth (71.46%). The presence of compounds in the methanolic extract of castor leaves was assumed to be toxic against A. niger. Based on GC-MS results, ricinine was the main compound in the methanolic extract of castor leaves. The potency of antifungal activity of castor methanolic extract may support its usage as renewable fungal toxicant in stored food.
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Introduction
Storing food commodities such as peanuts for long periods could lead to fungal contamination. There are several types of seed-borne fungi found to be predominant in peanut storage namely Macrophomina phaseolina, Rhizoctonia solani, Fusarium solani, F. oxysporum, Aspergillus flavus and A. niger (Rasheed et al, 2004). Some of these fungi produce mycotoxins e.g. aflatoxin and fumonisin that can contaminate the seeds. These mycotoxins have been shown to be co-produced and exhibited synergistic effect which subsequently aggravated the toxicity in contaminated food products (Maryam, 2006).
The presence of A. niger in the seeds during storage could reduce their viability. A. niger is a type of fungus that is very fast growing and difficult to control. Noonimabe et al. (2009) reported that the mycotoxin fumonisin B2 was produced by A. niger in coffee beans. Moreover, A. niger also involved in fruit spoilage. Its presence in stored products will affect the food quality, safety and lead...