Modified atmosphere packaging of fresh mushrooms

Abstract

The storage life o f harvested fruits and vegetables is influenced by their continued respiration and biochemical activity. Lowering the temperature, and modifying the atmosphere surrounding the product, can extend the shelf-life of the produce.Mushrooms (Agaricus bisporus) were placed into different structural containers covered with PVC films and stored at three temperatures. The effect o f key variables, such as temperature, respiration rate, critical and optimal concentrations of 0, and COz, package-weight/area ratio and film permeability, were studied.It was concluded that a highly perishable product, such as mushrooms, must be wrapped and refrigerated in order t o prevent transpiration and shrivelling. Modified atmosphere packaging (MAP) may be beneficial but was n o t found t o be essential. If a certain batch o f mushrooms respires faster than predicted, or is exposed t o large temperature fluctuations, MAP could have a damaging effect.Keywords: Modified atmosphere packaging (MAP); fresh mushrooms; shelf-life; film permeability. INTRO DU CTlO NThe storage life of harvested fruits and vegetables is influenced by their continued respiration and biochemical activity. Lowering the temperature, and modifying or controlling the atmosphere surrounding the product, reduces respiration and delays senescence, thus extending shelf-life. '9,In a sealed package, containing a fresh product, a modified atmosphere (MA) is created by respiratory oxygen uptake and carbon dioxide evolution. Consequently, equilibrium concentrations of oxygen and carbon dioxide are established, so that rates of gas transmission through the packaging material equal the produce respiration rate. The steady-state equilibrium will depend on several parameters, such as temperature, respiration rate, 0, and CO, permeabilities of the packaging material, fill-weight, free volume in the package, and film surface area.An optimum atmosphere should minimize respiration rate without danger of metabolic damage to the commodity. However, exposure of fruits and vegetables to 0 , levels below their tolerance limits and to CO, levels above their tolerance limits will cause anaerobic respiration and physiological disorders, respectively. 3,4For short-lived and expensive produce, of which mushrooms are a good example, there is an economic incentive to extend shelf-life by using modified

Quality and shelf life of packaged fresh sliced mushrooms stored at two different temperatures

“…These atmospheres may be considered as appropriate, since a CO 2 level of up to 5% is considered phytotoxic for mushrooms (López-Briones et al 1992). Moreover, O 2 levels below 2% might be related to anaerobic respiration in mushrooms (Beit-Halachmy and Mannheim 1992). However, at 9ºC, CO 2 and O 2 levels of 4.5% and 0.15%, respectively, were reached.…”

“…However, atmospheres above 5% CO 2 are considered as phytotoxic (López-Briones et al 1992). On other hand, O 2 levels below 2% are related to anaerobic respiration in mushrooms (Burton et al 1987, Beit-Halachmy andMannheim 1992) with the consequent accumulation of ethanol and acetaldehyde and the production of offodours (Tano et al 1999), besides the risk of growth of anaerobic pathogens (Sugiyama and Yang 1975). Mushroom development is inhibited by CO 2 concentrations upper than 5% (Murr andMorris 1975, López-Briones et al 1992) and O 2 levels lower than 5% (Roy et al 1995).…”

“…Refrigeration temperature is the main factor responsible for maintaining the quality of fresh mushrooms (Beit-Halachmy andMannhein 1992, Simón 2001) because it determines the speed of all metabolic processes and microbial growth. It also influences the atmosphere generated inside the packages because of its effect on the respiration rate of the product and the permeability of the film to gases (Zagory and Kader 1988).…”

Effect of respiratory gases (O2; CO2) on shelf-life of fresh oyster mushrooms packaged with different sealable polymeric materials

“…It was suggested that spoilage might be caused by the action of bacteria on the mushroom tissue and browning of mushrooms was due to a combination of autoenzymatic and microbial action on the tissue. Storage of mushroom in prepacks and the effects of carbon dioxide and oxygen on qualities of mushrooms had been reviewed by Halachmy and Mannheim (1992). The main oxidative reactions are enzymatic browning.…”

“…In the present study oxygen contents in trays were found to decrease sharply from 20% to 0.8% ~ 8.2% within 1 day storage. In another review by Halachmy and Mannheim (1992) recorded that modified atmosphere packaging (MAP) was not found to be necessary for mushrooms and could have a damaging effect causing anaerobic respiration as well as potential growth of anaerobic pathogens. Packaging mushrooms was essential for reducing transpiration and maintaining quality and therefore the correct water vapour transmission rate (WVTR) of the film is of great importance.…”