A review on environmental effect of various designs and types of drying methods

Abstract

Fruits and vegetables are nutritious and good in minerals, vitamins, and fib. Most fresh fruits and vegetables contain a minimum of 70% of moisture content which causes the formation of bacteria, fungi, and viruses to affect and cause the items to rot. But dried fruits contain only less than 20% of moisture content. So drying the fruits and vegetables helps to preserve the items for longer use without causing them to rot. Dried fruits have a great source of antioxidants and help in health benefits like improving blood flow, and reducing the effects of many diseases. Compared to fresh fruits, dried fruits are good in nutrition and have less weight for packaging and transportation usage. For drying materials, various types of solar dryers are used. Natural or open sun drying methods comparatively consume more than 12 h to dry material, whereas, direct and indirect drying methods would enhance the efficiency and dry the products quicker than open drying. For the consideration of quality drying and to increase efficiency, various modifications of solar dryers are designed and fabricated. In this review, we discussed the most appropriate developments in the drying of food items, required phase change materials (PCMs), performance, and environmental analysis of SD, and also reported the various designs of the solar drying techniques.