The effect of combining propionic and ascorbic acid on the keeping qualities of fresh minced pork during storage

In an attempt to improve the bacteriological quality of raw pork Longissimus dorsi mince meat, without adversely affecting the odour, colour and texture, the meat surface was treated with individual solutions of propionic acid and ascorbic acid and a combination of the two acids, at concentrations that had a preservative effect. A water-treated sample was used as the control. Bacterial colonization was determined over a 13 d refrigerated (4 degrees C) storage period. Propionic acid at 0.133 mol/L reduced the pseudomonad count by 3 log(10) cfu/g over this period, whereas 0.41 mol/L propionic acid reduced pseudomonad counts by 8 log(10)cfu/g. Combinations of ascorbic and propionic acid solutions were effective in reducing the microbial load of the minced pork. Headspace volatiles from untreated and treated minced pork were trapped on Tenax and analysed by GC-MS. Greater amounts of lipid oxidation were found in all acid-treated meats (apart from ascorbic) relative to the water-heated control sample. Meat colour was best preserved when ascorbic acid was present. Minced pork treated with solutions of propionic acid showed surface bleaching and an increase in lipid oxidation volatiles when compared with the control. All acid treatments decreased the water-holding capacity of the meat.