• Shelf Life Extension and Food Safety
• Water Activity
• Table — Water activity values of some Indian milk sweets and other products
• Hurdle Technology
• Processing Conditions

Section 5.1 - Process and Product Development Techniques

Shelf Life Extension and Food Safety (Pg 316)

From the public health viewpoint, products may be classified into two basic groups: (a) Fermented dairy products (pH below 4.6); and (b) Confectionery products (pH above 4.6). Generally, microbial hazards in the fermented products are related to spoilage organisms, primarily yeasts and moulds. However, other products when stored would pose substantial health hazard due to presence and multiplication of pathogenic organisms as well as spoilage by bacteria, yeasts and moulds.

Water Activity (Pg 317 - 318)

Most bacteria, yeasts and moulds are inhibited at Aw of 0.85. Growth of all bacteria can be stopped at Aw of 0.75, while growth of all yeasts and moulds requires Aw of 0.65.

Table 5.1.2 Water activity values of some Indian milk sweets and other products (Pg 318)

Hurdle Technology (Pg 318)
While water activity and sorption behaviour are useful parameters, they do not solely control or decide the shelf life or stability of a food. A better approach is to use them with several other parameters to make the product safe during the desired shelf life. The combined use of several parameters has been termed as Hurdle Technology or Combined Methods Approach. This approach involves manipulating the pH, Eh (redox potential), AW (water activity), solute type and concentration; giving heat treatments; incorporating chemical preservatives; using effective packaging techniques and maintaining chilled conditions of storage.

Processing Conditions (Pg 318 - 319)
The culturing process reduces the pH of the milk medium to less than 4.6. At this pH, most pathogenic and spoilage organisms cannot thrive or produce toxins, thus enhancing the product shelf life.

In case of liquid foods, the UHT processing is helpful in extending their shelf life. The application of microwave processing and irradiation provides scope to extend the shelf life of packaged foods. Research is needed to standardize parameters for these processes.