SHELF LIFE PREDICTION OF SELECTED TRADITIONAL STREET-VENDED FOODS USING ACCELERATED SHELF LIFE TEST METHOD

Abstract

This project was aimed at predicting the shelf life of selected traditional street-vended foods using accelerated shelf life technique (ASLT) via Arrhenius model. Commercial street-vended foods (plantain chips, akara Ogbomoso, kokoro, dodo Ikire, and chin chin) were obtained from vendors in Ibadan (South west region) of Nigeria. The ingredients for the production of the laboratory samples (Control) were also obtained from Oja-oba, Akure, Nigeria.The street- vended and laboratory-prepared (Control) samples were stored at three different temperature regimes; 35oC , 45oC, and 55oC respectively under a constant temperature incubator for a period of six (6) weeks. Changes in the physiochemical parameters (moisture content, pH, titratable acidity, free fatty acid, peroxide value, thiobabituric acid) and the microbial activities (total bacterial count, coliform count , yeast and mold count) were evaluated at seven days interval. The results showed that the trend of changes in the parameters measured for both street-vended and laboratory-prepared samples were not affected by the storage temperature differential. There was a general increase in the moisture content, total titratable acidity (TTA), free fatty acid, and microbial load irrespective of storage temperature while there was a decline in the case of pH values. It was also revealed that the values of parameters for the laboratory-prepared samples were generally lower than those of street-vended counterparts. The thiobabituric acid (TBA) values were used as an indicator of shelf life prediction for the fried products while the critical point for TBA from previous research is 1.0 mg ̸ kg. The regression graphs plotted, using first order reaction with the use of Arrhenius model, revealed that the estimated shelf life of the various products used in this study are as follows: street-vended plantain chips (11 days), control plantain chips (14 days), street-vended akara Ogbomoso (9 days), control akara Ogbomoso (12 days), street-vended kokoro (5 days), control kokoro ( 8 days), street-vended chin chin (7 days), control chin chin (10 days), street-vended dodo Ikire (5 days), and control dodo Ikire (7 days). The results clearly revealed that the laboratory-prepared samples generally had longer shelf life than the street-vended counterparts; indicating a good manufacturing practice as an influencing factor in the shelf life of food products.