Comperative study on the effectiveness of sodium metabisuphite, acetic acid and lemon juice in preservation of dried mangoes and tomatoes
Sokoine University of Agriculture
Mango and tomato are widely grown in the World. The present study was carried out to compare the effectiveness of three preservatives in retaining their quality attributes of mango and tomato and substituting the use of sodium metabisulphite with either the lemon juice or acetic acid. The three preservatives were sodium metabisulphite (0.1%), acetic acid (0.5%) and lemon juice (0.5v/v) studied at the respective level in bracket. Mango and tomato slices were dried in the walk - in solar dryer to attain the moisture range of 17 – 22% and packed in polythene package. The Completely Randomized Design (CRD) was used to assess the effectiveness of three preservatives while Randomized Complete Block Design (RCBD) was used in sensory evaluation test. Both descriptive and consumer test by the use of trained and untrained panelist respectively were done to assess the sensory profile and consumer acceptability. Microbial analysis for the total bacteria count and shelf life prediction by using linear model equation at different storage temperatures (35 and 45oC) were carried out. The results showed that sodium metabisulphite and lemon juice were the best in retaining the sensory attributes assessed. The reduction of microbial load for all the three types of preservatives was promising as they all lied within the acceptable values. The extensions of shelf life of the dried products were best achieved using sodium metabisulphite and lemon juice as they had longer shelf life than acetic acid treated samples, the results showed mango treated with sodium metabisulphite and lemon juice is shelf stable for 501 days while the one treated with acetic acid was shelf stable for 457 days at 25oC. The results also showed that mango have longer shelf life (11/2 years) than tomato (1/2 year) at 25oC and 28oC. The use of lemon juice was encouraged due to its effectiveness, cheapness, availability and positive health effects to the human body.
Sodium metabisuphite, Acetic acid, Lemon juice, Preservation of dried mangoes, Preservation of dried tomatoes