Page 50 - FoodFocusThailand No.238 January-February 2026

SMART PRODUCTION PRODUCTION
SMART

VALUE ADDITION OF TROPICAL

FRUITS THROUGH DRYING

TECHNOLOGIES COMBINED

WITH OSMOTIC DEHYDRATION PROCESS

Thailand is one of the world’s major producers of tropical fruits, supplying key export commodities
such as durian, longan, mangosteen, coconut, and mango. Despite their outstanding quality, these fruits
have short harvest periods and tend to enter the market simultaneously, resulting in seasonal oversupply,
rapid spoilage, and price volatility. In addition, sub-grade fruits, despite retaining excellent internal quality,
are often undervalued because they do not meet export appearance standards, leading to substantial
economic losses for growers and processors.

Nowadays, the market for dried fruits and vegetables in nutrient degradation, and provides textures closer to those of
Thailand continues to expand. In 2024, national production fresh fruit. As such, it is an increasingly attractive technology
reached 56,716 tons, representing an 8.7% increase from the for both processors and health-conscious consumers.
previous year, with more than 90% designated for export. The Osmotic dehydration (OD) involves immersing fruits or
export value for the first half of 2025 reached USD 96.7 million, vegetables in a concentrated solution, creating a concentration
reflecting a remarkable growth of 33%. Major markets include gradient that draws water out of plant cells. This reduces
China, the United States, Vietnam, Taiwan, and Malaysia. water activity prior to drying. OD is commonly applied before
These figures underscore the strong potential and continued hot-air drying, freeze drying, or freezing to help maintain
growth opportunities for Thailand’s dried fruit and vegetable product quality, minimize nutrient losses, and reduce energy
processing industry. consumption during subsequent drying stages. During OD,
Among various preservation techniques, drying technology two simultaneous mass-transfer mechanisms occur such as
is one of the most widely used methods for lowering water water loss, driven by diffusion and capillary flow, and solid
activity (a ) to below 0.6, thereby effectively inhibiting microbial gain, in which solutes from the osmotic solution are absorbed
w
growth and chemical deterioration. Conventional hot-air drying into the tissue, alongside the potential leaching of native fruit
is simple and cost-effective; however, it often results in hard solutes. These changes continue until the concentration
textures, darkened color, and nutrient loss. In contrast, freeze gradient diminishes and the system reaches equilibrium,
drying preserves superior color, flavor, and nutritional value, where no further net mass transfer occurs.
although it yields a sponge-like texture, requires long processing
times, and incurs high operational costs, making it suitable Key Factors Influencing Osmotic Dehydration
mainly for premium products. To address these limitations, • Solution temperature: Higher temperatures (typically
osmotic dehydration (OD) has emerged as a valuable pre- 25–60 °C) accelerate water loss but have a smaller effect on
treatment step prior to hot-air drying. This combined approach solute uptake.
enhances product quality, shortens drying time, reduces

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