Antimicrobial peptides are produced across all domains of life. Among these diverse compounds, those produced by bacteria have been most successfully applied as agents of biocontrol in food and agriculture. Bacteriocins are ribosomally synthesized, proteinaceous compounds that inhibit the growth of closely related bacteria. Even within the subcategory of bacteriocins, the peptides vary significantly in terms of the gene cluster responsible for expression, and chemical and structural composition. The polycistronic gene cluster generally includes a structural gene and various combinations of immunity, secretion, and regulatory genes and modifying enzymes. Chemical variation can exist in amino acid identity, chain length, secondary and tertiary structural features, as well as specificity of active sites. This diversity posits bacteriocins as potential antimicrobial agents with a range of functions and applications. Those produced by food-grade bacteria and applied in normally occurring concentrations can be used as GRAS-status food additives. However, successful application requires thorough characterization.

Bacteriophages are potentially useful in controlling foodborne pathogens on minimally processed products since phage application is a non-destructive treatment. The purpose of this study was to evaluate the efficacy of a newly isolated environmental bacteriophage against enterohemorrhagic Escherichia coli on fresh produce, and optimize the treatment with consideration for potential application. Seven anti E. coli O157:H7 EDL933 bacteriophages were isolated from various sources; the most promising was isolated from municipal wastewater. This isolate (designated as E. coli phage OSY-SP) was propagated with the host, in a growth medium, to a titer of 10(8) PFU/ml. Before inoculation into fresh produce, E. coli phage OSY-SP was incubated with the host bacterium, spent medium was filter-sterilized, and the resulting crude lysate was used as a source of phage inocula for preliminary experiments. For optimized testing, phage in the crude lysate was purified by ultra-centrifugation and resuspension in phosphate-buffered saline. Efficacy of phage treatments was determined as a function of fresh produce type (cut green pepper or spinach leaves), treatment time (2 or 5min rinsing), and temperature of holding treated produce (4°C, 25°, or a combination of both temperatures). Cut green pepper was treated with UV light, to eliminate background microbiota, then spot-inoculated with E. coli O157:H7 EDL933 on cut edges, and the inoculum was allowed to dry. Because of its susceptibility to damage, baby spinach leaves were not subjected to a decontamination treatment. These leaves were inoculated with the green fluorescent protein-labeled E. coli O157:H7 B6-914 to facilitate inoculum enumeration in the presence of background microbiota. Phage suspension was applied to the inoculated fresh produce that was subsequently held for three days under variable storage conditions. The optimized phage treatment decreased the populations of pathogenic E. coli by 2.4-3.0logCFU/g on cut green pepper (5-min rinse) and 3.4-3.5logCFU/g on spinach leaves (2-min rinse), during 72h storage. The majority of this decline was caused by the antimicrobial action of the phage. These findings suggest the utility of bacteriophage to selectively control pathogens on fresh produce.

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Food processing, packaging, and formulation strategies are often specifically designed to inhibit or control microbial growth to prevent spoilage. Some of the most restrictive strategies rely solely or on combinations of pH reduction, preservatives, water activity limitation, control of oxygen tension, thermal processing, and hermetic packaging. In concert, these strategies are used to inactivate potential spoilage microorganisms or inhibit their growth. However, for select microbes that can overcome these controls, the lack of competition from additional background microbiota helps facilitate their propagation.

Concord grape juice is associated with many health benefits, and so it can be sold at a premium price. However, there is currently no method to verify the percent composition of Concord grape juice in grape juice blends. In order to guard against potential adulteration, a rapid method for authentication is required. Fourier Transform infrared (FT-IR) spectroscopy was used to develop a model which predicts the percent composition of Concord grape juice. The model was based on a training set of 64 samples with Concord concentrations ranging from 50% to 100%. Data was collected on an external validation set with a standard error of prediction of 5.6% using 7 factors. The results suggest the feasibility of using FT-IR coupled with chemometrics as a production-scale tool for authentication claims of Concord in grape juice blends, protecting consumers and businesses against deceptive labelling.