The Implementation of a Decontamination Step during the Processing of Fresh-Cut Produce: a Compromise between Inactivation Efficiency and Quality Aspects

Peroxyacetic acid is a strong oxidizer and exerts important antimicrobial properties. The effect of a decontamination step with a moderate (80 mg/L) and a high (250 mg/L) peroxyacetic acid concentration on the shelf life of grated carrots stored under equilibrium modified atmosphere at 7 degrees C was determined and compared with the shelf life of unwashed and water washed carrots. Atmospheric composition, microbial parameters, sensory quality and nutrient content (carotenoids, phenols, alpha-tocopherol, antioxidant capacity) were analysed throughout storage. At the end of the study anoxic conditions were reached for unwashed carrots and carrots washed with 80 mg/L peroxyacetic acid. The microbial shelf life of water washed carrots was 4 days based on the yeast count, where the score for flavour exceeded the limit value after 5 days of storage. The total aerobic plate count and the yeast count determined the shelf life of carrots treated with 80 mg/L peroxyacetic acid on 5 days, whereas the score for flavour exceeded the limit value after 7 days of storage. None of the microbial parameters determined the shelf life of carrots washed with 250 mg/L peroxyacetic acid. However, this treatment had already a pronounced effect on the initial sensory quality. Water washing already decreased the content of all individually studied nutrients, except for the antioxidant capacity. Additional losses after adding peroxyacetic acid on day 0 were found for alpha-tocopherol and phenols. Regardless of the applied treatment, alpha- and beta-carotene remained stable during storage, but alpha-tocopherol declined significantly (P<0.05). The phenol content and the antioxidant capacity of unwashed and water washed carrots and carrots washed with 80 mg/L peroxyacetic acid increased significantly (P< 0.05) at the end of the storage period, whereas no changes were retrieved in carrots treated with 250 mg/L peroxyacetic acid. On the condition that carrots were packed under an adequate EMA, the 80 mg/L peroxyacetic acid treatment showed perspectives to extend their shelf life without pronounced effects on their nutrient content. Increasing the concentration to 250 mg/L resulted in the best quality from a microbial point of view, but showed an increased impact on both the sensory quality and the nutrient content.