PROCESSING ADVANCEMENT
What are your drying methods?
Drying Technology
For dried fruit products, one of the most important and time-consuming steps is the drying process, in which the water inside the fruit evaporates and is removed to achieve a dried product with good shelf life.
Traditionally, drying is often done at high temperatures all the way. Our process is divided into two stages:
Stage 1: High-temperature drying (free water removal)
In the first stage, we use hot drying air at temperatures similar to the traditional method (60–65°C). At this point, the fruit still contains a large amount of free water. Since free water evaporates quickly, the fruit temperature does not rise significantly—because evaporation is an endothermic process (it absorbs heat), helping prevent the product temperature from climbing up to the drying-air temperature.
Stage 2: Low-temperature drying (bound water removal)
When the free water is removed, the remaining moisture is tightly bound within the plant tissue structure. This water evaporates much more slowly. If we continued using hot air, the product temperature would gradually increase toward the drying-air temperature. That is why in Stage 2, we dry at a lower temperature of 25–30°C.
This technology is known as low-temperature drying (or heat pump drying). In heat pump drying, heat is “pumped” from a lower-temperature source to a higher-temperature one. To enable drying at such low temperatures, the drying air must be drier than usual. Therefore, we use a refrigeration/condensing unit (cooling coil) to condense and remove moisture from the air.
Benefits of Heat Pump Low-Temperature Drying
Applying heat pump technology and low-temperature drying helps the product better retain its natural color and flavor, and preserves sensitive nutrients such as vitamin C and polyphenols more effectively.
What is the difference between moisture content and water activity?
The Difference Between Moisture Content and Water Activity
Q: Which is more decisive for the shelf-life of dried foods: moisture content or water activity? A: Water activity.
Understanding the distinction between these two metrics is essential for controlling the shelf life and quality of food products:
- Moisture Content (MC): This is a quantitative measurement. It is defined as the total mass of water present in a food product, usually expressed as the number of grams of water contained in 100 grams of that food.
- Water Activity (aw): This is a qualitative measurement regarding the state of the water. It does not measure the weight of the water; instead, it measures the vapor pressure of the water in the food. If the water in a food product has higher vapor pressure, it means the water molecules have a higher ability to evaporate because they are not tightly bound to the food's internal structure. This "free" or unbound water is readily available ($available$) for micro-organisms to grow and for chemical or biochemical reactions (catalyzed by enzymes) to occur.
Why does this matter?
In food science, a lower Moisture Content does not always mean a safer product. In some cases, Food A with a lower moisture content can spoil faster (due to rapid microbial, chemical, or biochemical changes) than Food B with a higher moisture content. This happens because, despite having less total water, the water inside Food A is more "free" and unbound, resulting in a higher water activity (aw).
For a more detailed explanation, please watch the video below:
Why Does Drying Extend the Shelf-Life of Food?
A food product reaches the end of its shelf life when the internal changes within its structure exceed acceptable quality and safety standards.
These internal changes in food products or raw materials can be classified into four main categories:
Microbial Changes: The growth of bacteria, yeast, and mold.
Biochemical Changes: Reactions driven and catalyzed by emdogenous and exogenous enzymes present in the food.
Chemical Changes: Direct chemical reactions between different reactants over time, most notably oxidation (which causes off-flavors, rancidity, and color loss).
Physical Changes: Alterations in texture, structure, or moisture migration (such as staling or clumping).
How Drying Works to Preserve Food:
When the drying process is applied, it removes moisture and significantly reduces the water activity (aw) of the food (see our explanation on the difference between moisture content and water activity).
Blocking Micro-organisms: If the water activity drops below 0.6, micro-organisms completely stop growing and multiplying.
Slowing Down Other Reactions: Once microbial risks are eliminated, the product's shelf life is only affected by the remaining chemical, biochemical, and physical changes. Because low water activity also dramatically slows down these reaction rates, the overall shelf life of the food is greatly extended.
For a more detailed scientific explanation of how drying affects shelf life, please watch the video below:
Can you customize shapes and sizes of the dried fruits?
Answer:
Yes, we can adjust the shapes and sizes depending on the type of fruit and your specific market needs.
It is important to note that each fruit naturally requires a different slicing method, which leads to varying shapes and sizes. For example, even within the same mango variety, the initial sizes of the fresh fruits vary, meaning the final dried mango slices will naturally fall within a certain range of sizes and weights.
Depending on the fruit, we apply suitable cutting techniques - either before or after the drying process - to meet our customers' requirements. We always welcome open discussions with our partners to find the most optimal and efficient solution for both sides.
How Product Application Determines the Cut Size:
The ideal shape and size of a dried fruit slice often depend on how the end consumer will use the product. Common applications include:
Direct Consumption: Eaten directly as a convenient, healthy grab-and-go snack.
Yogurt Mixing: Stirred into plain yogurt to enhance both its nutritional value and sensory texture.
Toppings: Used as vibrant toppings for breakfast shakes, smoothies, and ice creams.
Ingredient Inclusion: Mixed into breakfast cereals, granola, nutrition bars, nut bars, or energy bars.
Premium Confectionery: Processed into high-end gourmet treats, such as dipping the fruit pieces into premium chocolate or matcha.
The Influence of Packaging Net Weight:
The final net weight of your retail pouch also plays a big role in choosing the right slice size. For instance, for smaller pouches with a net weight of 100g or less, we recommend choosing smaller slice cuts.
This greatly improves the consumer’s unboxing experience - it ensures there are plenty of pieces inside a single bag, making it much easier for a small group of friends or family to share and enjoy the snack together.
Soft dried mango in different cut sizes and shapes
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