Effect of types of packaging materials on the physiochemical and microbiological characteristics of African bush mango - soursop fruit bar during storage

Abstract

Abstract

This study evaluated fruit bar produced from the blends of African bush mango (Irvingia spp) and soursop (Annona muricata) in the ratio of 100:0, 0:100, 90:10, 80:20, 80:20, 70:30, 60:40, 50:50. The blends were properly mixed with the ingredients (citric acid and honey), heated at a temperature of 70 – 80 ⁰C in a water bath until it formed solid. It was then poured into a greased tray and oven dried at a temperature of 55 – 60 ⁰C for 8 hours in an oven dryer. The formulated fruit bar were allowed to cool, then packaged in three different packaging materials (low density polyethylene, high density polyethylene and foil). The different formulated fruit bars were subjected to sensory evaluation, proximate composition, micronutrient (vitamin C, phosphorus and calcium), microbial (total viable and mould counts) and physicochemical properties (brix, pH, and titrable acidity). Result showed that the overall acceptability of the formulated fruit bars differed significantly (p<0.05). In the proximate composition of the fruit bar, the moisture (2.56 % to 11.85 %), protein (2.17 % to 2.98 %), fiber (5,48 % to 13.63 %), crude fat (0.14 % to 1.07 %) and carbohydrate (71.41 % to 86.32 %) content of the fruit bar were not significantly different (p>0.05) among some samples while there was no significant different (p<0.05) among some other samples. The micronutrient composition of the fruit bar differs significantly (p<0.05) from each other. Also, the phosphorus (0.54 to 0.84 mg/100g) and calcium (11.20 to 20.12 mg/100g) content were high, while the vitamin C (48.50 to 84.50 mg/100g) content increased with the increase in the proportion of the blends. The microbial count of the products increased during storage. The total viable count of the sample showed that majority of the samples stored in high density polyethylene had high growth of microorganisms (2.7 × 10⁹ cfu/ml) and the least from the low density polyethylene (1.4×10⁵ cfu/ml). Based on the mould count, majority of the samples stored in the foil had values ranging from 1.0×10 to 7.0×10² cfu/ml and the least from the low density polyethylene (no growth). During the 4 weeks storage, the titrable acidity of the samples increased progressively, with the samples stored in the low density polyethylene having the highest value (1.50 %) and the high density polyethylene having the least value (1.43 %). The pH of the stored samples decreased, with samples stored in the low density polyethylene having the highest value (3.57 %) and least value obtain from the high density polyethylene (3.69 %). The sugar level of the stored sample increased with the samples stored in the low density polyethylene having the highest value (9.40 %) and the high density polyethylene has the least value (9.90 %).

Key words: African bush mango (Irvingia spp), Fruit bar, Microbes, Packaging materials, Soursop (Annona muricata)