UNDERSTANDING THE PRESERVATION TECHNIQUES

(The conceptual and methodological difference in Drying & Dehydration methods)

Drying and dehydration are two processes adopted to remove excessive moisture from food products in an endeavour to preserve them. While we often use the two of them interchangeably, in our daily lives, there is a world of difference between the two terms.

Let’s understand the difference:

Drying:

Drying refers to the general process of reducing moisture content from a material, whether it is a food product, a substance, or even a surface. It involves the removal of water and inadvertently other flavour and nutrition bearing Essential Oils through evaporation caused due to heat from a direct source. Drying can occur naturally (e.g., sun drying) or through other means (e.g., using heated ovens, or heating mantle, fire).

This completion of this process takes a number of days depending on demographics and crop health, but since the only the top or bottom half of material placed receives the heat, the wet part houses the right environment of humidity and heat to aid the growth of harmful and mostly carcinogenic microorganisms like Aflatoxins, Mycotoxins and fungi. Further, when mass-processors adopt the heat from fire to expedite this drying process, the carbon elements from the smoke aid the growth of Polycyclic Aromatic Hydrocarbons – an highly deadly carcinogenic compound.

Dehydration:

Dehydration specifically refers to the process of removing moisture from food products. It is a more precise term largely associated with food preservation. Dehydration aims to extend the shelf life of foods by reducing water content to a level that inhibits the growth of spoilage microorganisms, this involves bringing down the water activity of any product to a level that it does not age or spoil at the rate it normally does. Dehydration method involves use of precise machinery which remove water through indirect heating and wherein all parameters that effect the excessive moisture removal can be controlled or modulated, these parameters include air flow, temperature, humidity, exposure time and cooling time. This control results in unaltered, equally nutritious and clean product which has just lost it unwanted moisture but has retained its Oils, colour, flavour, texture and all other innate characteristics. Since this process is completed in matter of hours where the material is constantly being turned and humidity is continuously being kept down, there is no time or environment build-up that may aid the growth of any harmful microorganisms or the presence of Polycyclic Aromatic Hydrocarbons – an highly deadly carcinogenic compound. Being processed in a controlled environment without the loss of any nutrients, machine dehydrated products have the unique ability to regain their original shape and size when immersed in potable water or when heated in water.

While drying can refer to any material’s moisture removal and inadvertently its dissolved naturally occurring oils, the term dehydration is primarily focused on food products.

Dehydration methods are designed to retain the food’s nutritional value, flavor, and texture while achieving the desired moisture content for preservation .

Points of Consideration:

1. Nutrient loss: The drying process can lead to nutrient loss in food products, especially heat-sensitive Essential Oils, vitamins and antioxidants. However, controlled dehydration methods are known to better retain nutrients compared to drying methods.

2. Quality and texture changes: Uncontrolled drying process can lead to changes in the texture, colour, and overall quality of the food product. Care taken in the controlled dehydration method not only retains original texture, colour, and overall quality of the food product but also yields a contaminant free product.

3. Growth of Microorganisms: Drying being an uncontrolled method has no parametrial control and thus the humidity caused by innate moisture aids the growth of microorganisms like Aflatoxins, Mycotoxins and fungi. The parametrial dehydration method exposes the entire surface area in a dry environment to the avoid this growth of microorganisms, moreover the low temperatures stops the volatile essential oils from evaporating with water. READ OUR BLOG ON PRESENCE OF HARMFUL GROWTHS IN SUN-DRIED PRODUCTS HERE

4. Polycyclic Aromatic Hydrocarbons (PAH): Since the sun-drying method takes a number of days to complete, some processors and farmers have resorted to providing heat from fire to avoid humidity fallback during the night time and to expedite the drying during day. The smoke thus arising from this fire causes the growth Polycyclic Aromatic Hydrocarbons (PAH) which are highly toxic, mutagenic, carcinogenic, teratogenic, and immunotoxicogenic to all life forms. However, it has recently been studied that due to rising pollution levels across the globe, the carbon elements in the air settle on sun-dried material which are placed openly under the sun. Controlled Dehydration process is carried out in close chambers and through indirect heating methods there is no presence of PAH’s. READ OUR BLOG ON PRESENCE OF HARMFUL GROWTHS IN SUN-DRIED PRODUCTS HERE

5. Salmonella: Salmonella are infections that reside in the intestinal tracts of which are transferred to openly laid out material which are being sun-dried. These infections, even though being infested in small amounts, grow in number and slowly effect the entire lot. Needless to mention again here that since Controlled Dehydration process is carried out in close chambers and through indirect heating methods there is no presence of Salmonella or any Infections in them. READ OUR BLOG ON PRESENCE OF HARMFUL GROWTHS IN SUN-DRIED PRODUCTS HERE