Effect of high argon pressure and modified atmosphere packaging on the white mushroom (Agaricus bisporus) physico-chemical and microbiological properties

© 2011 VÚP Food Research Institute, Bratislava 167 Edible mushrooms are widely consumed in many parts of the world owing to their characteristic taste, aroma and nutritional relevance. Edible mushrooms are valuable components of diet and their culinary and commercial values are mainly due to their organoleptic properties such as texture and flavour [1, 2]. They also are excellent source of several essential amino acids, vitamins (B2, niacin and folates) and minerals (potassium, phosphorus, zinc and copper). Mushroom protein is comparable to the high-quality animal protein and superior to vegetables and cereals proteins [3, 4]. Postharvest browning of Agaricus bisporus mushrooms is a severe problem that reduces the shelf life of harvested ones because of their continual respiration and biochemical activities. Mushrooms have a shelf life of 3 to 4 days, which is short compared to other vegetables at room temperature, because they have no cuticles to protect them from physical or microbial attack or water loss [5, 6]. More importantly, the high tyrosinase and phenolic contents of mushrooms make them prone to rapid enzymatic browning [7]. This phenomenon is the major cause of overall quality loss of mushrooms accounting for reduction in market value. Moulds, bacteria, enzymatic ac tivity and biochemical changes can cause spoilage during storage. Gram-negative microorganisms, such as Pseudomonas tolaasii and Pseudomonas fluorescens, and yeasts, such as Candida sake, have been associated with mushroom spoilage [1, 6]. Storage of mushrooms affects their quality in the following ways: darkening of the tissue, elongation of the stems, opening of the caps and harden ing of the flesh [8]. Therefore, one alternative to extend mushroom shelf life during postharvest storage and commercialization is modified Effect of high argon pressure and modified atmosphere packaging on the white mushroom (Agaricus bisporus) physico-chemical and microbiological properties