Freeze dried blueberries

Freeze drying—technically known as lyophilisation, or cryodesiccation is a dehydration process typically used to preserve a perishable material or make the material more convenient for transport. A freeze dried fruit is a dehydrated fruit derived from lyophilisation which can be stored for longer duration and can be consumed throughout the year.

Process of freeze drying is practically done in three main phases:
• Freezing, or sub-cooling of product below its eutectic point (cca. -30°C and lower);
• Dehydration (drying) by ice sublimation under vacuum; and
• Completion of product drying up to moisture content lower than 3% by the normal vacuum drying.

Traditionally, freeze-drying is performed at vacuum (vacuum freeze-drying, VFD), resulting in extensive drying periods with high operating costs. In order to shorten this period, alternative processes can be used, such as atmospheric freeze-drying (AFD), where the primary drying stage (sublimation) occurs at atmospheric pressure. AFD has been used successfully for drying of berries. Traditional freeze drying (lyophilisation) is used to quick freeze and vacuum moisture from a blueberry. This gets the blueberry to a 2 % moisture level where it is crunchy.

The freeze dry blueberry maintains all of the nutrients of the blueberry minus the water and an intense blueberry flavor. According to one study, freeze drying resulted in a higher retention of total polyphenols and anthocyanins as well as higher antioxidant activity in the glycoside forms. (International Journal of Food Engineering, Volume 4, Issue 6 July 2008)
Freeze dried blueberries

Food enrichments

Enrichment, a term often used interchangeably with fortification, is the addition of nutrients to achieve concentration specified in standards of identity.

In foods, enrichment refers to the addition of vitamins, minerals and/or protein to raise the nutritive value.

Because of the vital role vitamins and minerals play in the body’s processes, many foods are enriched or fortified with additional vitamins and minerals. Many foods have a diminished nutritive content as a result of loss in refining or processing and can benefit from the enrichment.

Also, some foods provide effective vehicles for distribution of a nutrient. Enrichment of cereal grain products with iron, thiamin, riboflavin and niacin has been a remarkably effective and efficient means of enhancing the nutrient quality of the food supply and is a classic example of an effective well-designed public health approach to providing needed nutrients.

Cereal grains were selected for enrichment because they are eaten frequently by virtually all populations groups.

The decision to fortify with a particular nutrient is a complex one. It starts with the realization that a significant number of people are not obtaining desirable levels of a specific nutrient and the determination that the food to be fortified makes an appreciable contribution to the diet.

It must be further ascertained that the fortification will:
*not result in an essential nutrient imbalance
*the nutrient is stable under storage
*capable of being absorbed from the food
*that toxicity from excessive intakes will generally not occur.
Food enrichments 

Losses of nutrients during food processing

Some losses during in certain nutrients during food processing are inevitable.

The major consideration in evaluating food processing from nutritional stand point is that tradeoff between increase food availability and the effect that each of the various processing methods has on nutrients and food quality.

The degree of nutrient loss and the relative importance of the loss of a specific nutrient from a particular commodity should also be taken into consideration.

For example, vitamin C loss from milk during pasteurization and refrigerated storage is relatively unimportant, since it is insignificant source of this nutrient in the daily diet when compared with other foods as citrus fruits and juices.

The net effect of food processing on product quality is positive. The nutritive value of foods may be improved by increase in nutrient content and/ or digestibility of food component.

The aesthetic qualities of foods are also improved, resulting in enhanced appeal of the food to the appetite and better nutrient retention through consumption.
Losses of nutrients during food processing