Use of Ultra-Violet (UV) Light to Increase the Shelf Life of Raw Diced Beef

Pugsley, Rhys (2020) Use of Ultra-Violet (UV) Light to Increase the Shelf Life of Raw Diced Beef. Masters thesis, University of Central Lancashire.

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Ultra-violet light has gained recent attention for its potential use as a non-thermal, non-chemical decontamination tool to reduce microbial loads across various food products and food contact surfaces. Most commonly, the current method to reduce and control bacteria is by controlling environmental conditions such as temperature, pH, available water, preservatives and by constantly implementing successful hygiene protocols. This study aimed to investigate the effect of UV light irradiation on food contact surfaces and the subsequent effect on the shelf-life of the raw diced beef being processed within a red meat processing facility. It was anticipated that the shelf life of the final product will be increased to greater than pack + 10 days. The study consisted of determining the Total Viable Count (TVC) of four food contact surfaces involved in the processing of diced beef at retail level, and assessing the current shelf life of the product by analysing the visual properties of the finished pack and testing various indicator organisms including total viable counts, enterobacteriaceae, pseudomonas, e.coli and salmonella prior to the intervention. Food contact surface analysis included taking swabs at the start of production at 6am, the middle of production at 12pm and at the end of production at 3pm. One swab was collected at each time slot and location twice per week, totalling 72 swabs during the pre-intervention. Finished pack analysis consisted of collecting 3 finished packs, 3 times per week for an external accredited laboratory to complete shelf life testing. On these testing days, the same amount of packs were collected and analysed for the visual properties and graded against a chart by a team of trained panellists. After the installation of the UV light strobe, one of the four food contact surfaces (Conveyor 2) was treated continuously with UV light, and similar microbial tests were repeated post intervention and results compared to pre-trial. Overall the ultra-violet light did have a statistical significant effect (p<0.05) on the reduction of bacteria present on conveyor 2 with mean log reductions of 2.53 log cfu/cm2 at 12pm and 1.78 log cfu/cm2 at 3pm. However, no other surface tested had a significant difference between pre-intervention and post intervention. Finished pack analysis revealed that the decontamination of conveyor 2 had no impact on the microbiological counts post-intervention. There was no impact on the visual properties post intervention therefor the shelf life of final pack was not increased to greater than pack + 10 days.

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