Food and nutrition.pdf

Dried Fruits and Vegetables 241can be extended throughout the year. In general the method gives goodretention of colour in the dried food and produces a sweeter, blandertasting product. However, aci1s are also removed from fruits during theprocess ;and the lower acidity of the product may alloW mould growth if_ the food is not properly dried and packaged.In a more complex method to that described in Figure 10, fruit is firstboiled in 20% syrup and then soaked overnight. The fruit is then strained. from the syrup and transferred each day to 40% and 60% syrups in tum,with optional boiling for 10 minutes at each transfer.After soaking, the syrup is diluted to approximately half of theoriginal concentration. Each day the most dilute syrup (10%) is used forother products and a new 60% syrup is made up. The advantages of thismethod include reuse of sugar syrups and a softer texture in the finalproduct. In Figure 11, the containers therefore circulate 'backwards' asthey contain more dilute syrup. Some producers have even more stagesin the process and may uansfer fruit into increasing sugar concentrationseach day for up to fourteen days. This results in a succulent, soft texturein ,the final product.Types of DryersThe higher value of dried fruit and vegetable products, comparedfor example to cereals crops, may justify the higher capital investment ina fuel-fired dryer or electric dryer and the extra operating costs for thefuel or electricity. These types of dryer allow higher drying rates andgreater control over drying conditions than do solar or sun drying andthey can therefore result 'in a higher product quality.However it is necessary to make a careful assessment of the expectedincrease in income from better quality products compared to the additionalexpense, to make sure that this type of dryer is cost-effective. Sun dryingis only possible in areas where, in an average year, the weather allowsfoods to be fully dried immediately after harvest. The main advantagesof sun drying are the low capital and operating costs and the fact thatlittle expertise is required.PackagingIf the climate is dry, it may not be necessary to package dried foodsas they will not pick up moisture from the air. However a humid climateis likely to vesult in dried foods gaining moisture and going mouldy. The~ stability of· dried foods depends not only on the humidity of the air at,vhich it ~ood neither gains nor loses weight (the 'Equilibrium RelativeHumidity'), but also on the type of food. Different foods can be groupedaccording to their ability to absorb moisture from the air. The two groups