191: Combined Efficacy of Bacterial Fermentates to Control Growth of Penicillium Commune and Aspergillus Flavus and Extend the Shelf-Life of Shredded Cheddar Cheese

Introduction

One of the leading causes of economic loss in the cheese industry is mold spoilage. Mold growth can render cheese unsellable, resulting in waste, product recalls, and significant financial losses for cheese producers. Mold growth on cheese causes sensory defects such as discoloration, odor, flavor or texture changes. Additionally, preventing mold growth mitigates health risks associated with mycotoxin-producing molds.

Methods

The antifungal effectiveness of three bacterial fermentates – CytoGuard (CG), MicroGard 100 (MG), and Inhibit violet (IV) against Penicillium commune and Aspergillus flavus, was evaluated on potato dextrose agar (PDA) using an agar dilution assay. The measured widths of the mold colonies were used to evaluate the growth inhibitory effect of each fermentate. A compositional analysis of each fermentate was performed using high performance liquid chromatography (HPLC) to identify antifungal components. The antifungal effectiveness of various combinations was evaluated using the checkerboard assay. Cheese samples with selected concentrations of two fermentates (CG and IV) were inoculated with mold conidia (2 x 104 CFU/g) and monitored for visible mold growth during refrigerated (7°C) storage for 40 days. Inoculated cheese without fermentate served as control.

Results

Mycelial width for both molds decreased with increased concentration of CG (2.5% to 4.0%) and IV (4.0% to 7.0%) (p < 0.05). More antifungal compounds were detected in CG compared to IV and MG. Compared to A. flavus, P. commune was more sensitive to CG and IV. No visible growth of P. commune occurred on PDA containing 3.5% IV + 3.5% CG. Similar results were observed for A. flavus on PDA with 4.5% IV + 2.5% CG. On control cheese (7°C) growth of P. commune and A. flavus was observed after 10 and 20 days, respectively. In contrast, cheese with 1.25% IV + 0.62% CG prevented growth of P. commune and A. flavus for more than 40 and 25 days, respectively.

Significance

Combinations of fermentates can be used as a natural mold inhibitor to prevent mold spoilage in shredded cheese and decrease economic losses for cheese producers. This strategy is in keeping with consumer preference for more natural food additives, and food processors’ aim to produce “clean label” products.

Authors: Shannita Ramnarine, Aubrey Mendonca