Moisture, Ash Testing in Food Processing
Moisture content is one of the most important characteristics in consumer sensory perception of food. Change in moisture content will dramatically affect flavor and texture as well as physical and chemical properties, as water gives chemicals a helpful medium to catalyze chemical reactions (water activity). The presence of free moisture is directly related to water activity; the higher the water activity, the more susceptible the food will be to interactions with microbes and its environment.
Knowing and plotting water content is a useful way of locating the right packaging for each environment, which improves shelf life. The analysis of ash content in foods is simply the burning away of organic content, leaving inorganic minerals. This helps determine the amount and type of minerals in food; important because the amount of minerals can determine physiochemical properties of foods, as well as retard the growth of microorganisms. Therefore, mineral content is a vital component in a food’s nutrition, quality and, like water, microbial viability.
Foods have high and low moisture content limits beyond which the product becomes objectionable from either a sensory or safety perspective. In dry brittle foods with low moisture content, such as dry cereal and dehydrated foods, upper moisture content limit is important; the food can absorb water and become moist, undesirable and prone to microbe contamination. In wet foods, such as muffins, the lower moisture content limit is monitored to make sure the food doesn’t become stale or distasteful. Finding and testing for these limits is essential to produce accurate manufacturer specifications for moisture.
Guaranteeing food falls within these limits ensures the production of a quality food product that will not expire prematurely. Each food also has its own longevity and packaging concerns as well as mineral content considerations.