There has been a wealth of recent research both on the importance of fruit and vegetable consumption to health and on new technologies to preserve the nutritional and sensory qualities demanded by consumers. Micronutrients, biologically-active, non-nutritive secondary metabolites may be preserved and even enhanced during food production, so the relative impact of processing have to be minimized: it is the case of mild-technologies. Before they are marketed and consumed, the fresh vegetables may undergo a series of technological treatments of mild intensity such as to ensure both their freshness and natural features, at the same time seeking to increase their value and convenience of use (Fig.1).
Convenience Food Technologies
In keeping with shifting consumer trends and changing eating patterns, food industries are providers of innovative food solutions to varying degrees of convenience, that are: ready-to cook, ready-to-reheat, ready-to-eat dishes with vegetables. The vegetables formulated into convenience meals are value-added ingredients that enhance flavour, appearance and mouthfeel. Moreover, they also manifests manufacturers’ dedication to superior, quality cuisine. So, most frozen convenience meals and entrees present grilled vegetables with vibrant colours and distinct grill marks. In several convenience foods, vegetables are fried, prepared with a technique called “stir fry” that required a minimum amount of fat to make crisp the vegetable surface. The wide variety of product categories, like chilled, frozen and ambient recipe dishes, ready meals, meal components and snack meals, inspired by traditional national recipes, Mediterranean or oriental cuisine, sometimes providing healthy meal options (fresh, flavoursome, nutritionally-balanced, salt- and fat-reduced), and targeted at various channels within the food distribution market (food retail, catering and foodservice, the out-of-home eating sector), are prepared by food industry by means of the so called “convenience food technologies”.
Preserving fresh vegetables by washing
The preservation of fresh vegetables and the disinfection of processed vegetables are critical points along the processing line with a definitive effect on the safety, quality and shelf-life of the product. Chlorine, which is the most widely used sanitizing agent for fresh cut vegetables, is forbidden in organic food production (EU 2092/91) due to the environmental and health risks. There is also a need for minimizing the water consumption and wastewater discharge rates in the industry. Therefore, both the organic and the conventional processing sectors are now seeking alternatives to chlorine which assure the safety of the products, maintain the quality and enable a shelf-life as long as chlorine. Ozone has many characteristics that make it attractive for use as a sanitizer in food processing. High reactivity, penetrability and spontaneous decomposition to a non-toxic product (O2) make ozone a viable disinfectant. It does not remain in water or on the surface of the product for a significantly long period of time, thus its use may be considered as a processing method rather than a food additive. Many studies show that bubbling gaseous ozone in water is the most effective ozonation method for vegetables and can be effective even in lower concentrations. The use of a combination of ozone and chlorine resulted in equivalent or better microbial reduction, an extension of the shelf life (as determined by appearance) of salads, and a reduction in process water turbidity than chlorine alone. In post-harvest storage, there is a great deal of empirical activity in the evaluation of ozone for a diversity of commodities such as apples, cherries, carrots, garlic, kiwi, onions, peaches, plums, potatoes, and table grapes. However, excessive exposure to ozone may injure plant tissue and effectively reduce storage or sensory life (University of California, ANR Division, 2004).