Exploiting the microbiota of organic and inorganic acid-treated raw poultry products to improve shelf-life

Introduction

Targeted amplicon sequencing of the 16S rRNA delineates the complex microbial interactions that occur during food spoilage, providing a tool to intensively screen microbiota response to antimicrobial processing aids and interventions. The current research determines the microbiota and spoilage indicator (total aerobes and lactic acid bacteria; LAB) response to inorganic and organic antimicrobial intervention use on the shelf-life of fresh, never-frozen, skin-on, bone-in chicken wings.

Methods

Wings (n=200) were sourced from local processor and either not treated (NT) or treated with 15-s dips of tap water (TW), organic (peracetic acid; PAA), inorganic acids (sodium bisulfate; SBS), and their combination (SBS + PAA). Wings were stored (4°C) and rinsed in neutralizing Buffered Peptone Water (BPW) for 1 min on d 0, 7, 14, and 21 post-treatment. Spoilage indicators, aerobic mesophiles and LAB, were quantified from rinsates. Genomic DNA of d 14 and 21 rinsates were extracted, and V4 of 16S rRNA gene was sequenced. Sequences were analyzed using QIIME2.2019.7. APC and LAB counts were reported as Log10 CFU/g of chicken and analyzed in R Studio as a General Linear Model using ANOVA. Pairwise differences were determined using Tukey's HSD (P£0.05).

Results

Spoilage was indicated for all products by day 21 according to APC counts (>7 Log10 CFU/g); however, wings treated with SBS and SBS + PAA demonstrated a 7-day extended shelf-life compared to those treated with NT, TW, or PAA. The interaction of treatment and time impacted the microbial diversity and composition (p < 0.05), with those treated with SBS having a lower richness and evenness compared to those treated with the controls (NT and TW; p < 0.05, Q < 0.05). On d 14, those treated with SBS and SBS + PAA had lower relative abundance of typical spoilage population while having a greater relative abundance of Bacillus spp. (~70 and 50% of population; ANCOM p < 0.05). By d 21, the Bacillus spp. populations decreased below 10% of the population among those treated with SBS and SBS + PAA.

Discussion

Therefore, there are differential effects on the microbial community depending on the chemical intervention used with organic and inorganic acids, impacting the microbial ecology differently.

Impact of Acidulants on Salmonella and Escherichia coli O157:H7 in Water Microcosms Containing Organic Matter

As demands for fresh water become more competitive between the processing plant and other consumers of water such as municipalities, interest has grown in recycling or reusing water for food processing. However, recycling the processing water from a poultry plant, for example, represents challenges due to increased organic loads and the presence of bacterial contaminants including foodborne pathogens. The objective in the current study was to evaluate the inactivation of Salmonella and E. coli O157:H7 using combinations (0.5% and 1%) of sodium bisulfate (SBS) and 1% lactic acid (LA) in water and water with organic matter in the form of horse blood serum (0.3%) with exposure times of 1 min and 5 min. Pathogen reductions after a 5 min exposure time were greater than corresponding reductions after a 1 min exposure time for all acid solutions. The Salmonella counts were significantly reduced (i.e., ≥1 log-unit) in all acid solutions after a 5 min exposure time with the combination of LA + SBS acid solutions being more effective than the corresponding 2% LA solutions. None of the acid solutions were effective in reducing the E. coli O157:H7 after a 1 min exposure time. The 1% LA + 1% SBS solution was the most effective acid solution against both pathogens and was the only acid solution effective in reducing E. coli O157:H7 by at least one log unit after 5 min of exposure.

Comparison of ready-to-eat “organic” antimicrobials, sodium bisulfate, and sodium lactate, on Listeria monocytogenes and the indigenous microbiome of organic uncured beef frankfurters stored under refrigeration for three weeks

Listeria monocytogenes has been implicated in several ready-to-eat (RTE) foodborne outbreaks, due in part to its ability to survive under refrigerated conditions. Thus, the objective of this study was to evaluate the effects of sodium bisulfate (SBS), sodium lactate (SL), and their combination as short-duration antimicrobial dips (10-s) on L. monocytogenes and the microbiome of inoculated organic frankfurters (8 Log10 CFU/g). Frankfurters were treated with tap water (TW), SBS0.39%, SBS0.78%, SL0.78%, SL1.56%, SBS+SL0.39%, SBS+SL0.78%. In addition, frankfurters were treated with frankfurter solution water (HDW)+SBS0.78%, HDW+SL1.56%, and HDW+SBS+SL0.78%. After treatment, frankfurters were vacuum packaged and stored at 4°C. Bacterial enumeration and 16S rDNA sequencing occurred on d 0, 7, 14, 21. Counts were Log10 transformed and calculated as growth potential from d 0 to d 7, 14, and 21. Data were analyzed in R using mixed-effects model and One-Way ANOVA (by day) with differences separated using Tukey’s HSD at P ≤ 0.05. The 16S rDNA was sequenced on an Illumina MiSeq and analyzed in Qiime2-2018.8 with significance at P ≤ 0.05 and Q ≤ 0.05 for main and pairwise effects. An interaction of treatment and time was observed among the microbiological plate data with all experimental treatments reducing the growth potential of Listeria across time (P < 0.0001). Efficacy of treatments was inconsistent across time; however, on d 21, SBS0.39% treated franks had the lowest growth potential compared to the control. Among diversity metrics, time had no effect on the microbiota (P > 0.05), but treatment did (P < 0.05). Thus, the treatments potentially promoted a stable microbiota across time. Using ANCOM, Listeria was the only significantly different taxa at the genus level (P < 0.05, W = 52). Therefore, the results suggest incorporating SBS over SL as an alternative antimicrobial for the control of L. monocytogenes in organic frankfurters without negatively impacting the microbiota. However, further research using multiple L. monocytogenes strains will need to be utilized in order to determine the scope of SBS use in the production of RTE meat.