Microbial and Storage Stability of Biscuits Produced from Cassava and Soybean Flour Mixed with Pineapple Pulp Blend

Abstract

The research examines the microbial and storage stability of biscuits produced from composite blends of cassava and soybean flour supplemented with pineapple pulp. The formulations involved: Control (AO) with 100% wheat flour, AA with 100% cassava flour, AB comprising 80% cassava, 15% soybean, and 5% pineapple pulp, AC with 60% cassava, 30% soybean, and 10% pineapple pulp, and AD containing 40% cassava, 45% soybean, and 15% pineapple pulp. Microbial analysis revealed that the initial microbial loads were low across all samples, ranging from 2 × 10² CFU/g to 5 × 10² CFU/g, with the Control (AO) showing 3 × 10² CFU/g and the AA formulation (100% cassava flour) showing the highest initial count at 5 × 10² CFU/g. Following six months of storage, the samples retained markedly higher microbial counts, ranging from 6 × 10² CFU/g (AD) to 6 × 10⁴ CFU/g (AA), indicating insufficient preservation methods. Colony and cellular morphology showed that Aspergillus spp. was the predominant contaminant in the cassava-only and lower-soybean formulations (AA and AB), while Mucor spp. dominated the wheat-based control and the formulations with higher soybean and pineapple pulp inclusion (AC and AD), indicating that formulation composition influenced the pattern of fungal contamination. This research underscores the necessity of optimising formulation ratios and storage conditions to enhance the nutritional value and shelf stability of biscuits while managing microbial growth.