Review on low‐temperature heat pump drying applications in food industry: Cooling with dehumidification drying method

Effect of different drying methods on free amino acid and flavor nucleotides of scallop (patinopecten yessoensis) adductor muscle

The effects of hot air drying (HAD), vacuum hot air drying (VHAD), microwave drying (MWD), and vacuum freeze drying (VFD) on free amino acids (FAAs) and flavor nucleotides in scallop adductor muscle (SAM) were studied. The liquid chromatography and multidimensional infrared spectroscopy (MM-IR) were used. Compared with fresh SAM, the main FAAs were glycine, alanine, arginine, and glutamic acid in dried SAM. The total FAAs content in VFD group was 1.40-1.90 times of the other group. The umami taste nucleotides (IMP and AMP) content in the VFD and MWD groups was significantly higher than that in HAD and VHAD groups. Equivalent umami concentrations were found: VFD > MWD > VHAD > HAD. MM-IR analysis was an efficient method for identifying taste components. The results revealed FAAs and flavor nucleotides and the mutual adjustment of compounds were related to drying method, and VFD was preferred for taste substance retention in scallops.

Mathematical modeling of nutritional, color, texture, and microbial activity changes in fruit and vegetables during drying: A critical review

Retention of quality attributes during drying of fruit and vegetables is a prime concern since the product's acceptability depends on the overall quality; particularly on the nutritional, color, and physical attributes. However, these quality parameters deteriorate during drying. Food quality changes are strongly related to the drying conditions and researchers have attempted to develop mathematical models to understand these relationships. A better insight toward the degradation of quality attributes is crucial for making real predictions and minimizing the quality deterioration. The previous empirical quality models employed kinetic modeling approaches to describe the quality changes and therefore, lack the realistic understanding of fundamental transport mechanisms. In order to develop a physics based mathematical model for the prediction of quality changes during drying, an in-depth understanding of research progress made toward this direction is indispensable. Therefore, the main goal of this paper is to present a critical review of the mathematical models developed and applied to describe the degradation kinetics of nutritional, color, and texture attributes during drying of fruit and vegetables and microbial growth model during storage. This review also presents the advantages and drawbacks of the existing models along with their industrial relevance. Finally, future research propositions toward developing physics-based mathematical model are presented.

A comprehensive review of solar photovoltaic hybrid food drying systems

Demand for all resources, especially food, water, and energy, has increased with the rapid increase in the world population. These resources are limited and not enough for the growing population of the world. Therefore, the food-energy-water nexus approach has gained much attention in recent years. Less energy and water consumption and less waste generation became the target for the more sustainable food production. Qualitative and quantitative losses in agricultural commodities growing in rural areas depend both on the structure of foods and incorrect or inadequate process applied to postharvest operations to preserve food. Therefore, drying is the most preferred food preservation method. To minimize the energy consumption during drying process, renewable energy technologies are emerging as an alternative solution. It reduces dependency of fossil fuels, adds value to agricultural products to meet the increasing demand, and minimizes qualitative and quantitative losses. In this work, theoretical and experimental studies of photovoltaic-thermal (PV/T) or photovoltaic (PV) integrated food-drying systems were comprehensively reviewed. The researches covered in this review are classified into three groups: PV module integrated, PV/T collector-assisted food-drying systems, and PV/T-assisted heat pump-drying systems.