Moisture content in food can have a significant impact on factors such as the product’s taste, texture, appearance, shape, and weight. It has implications on legal and labeling requirements, economically important requirements, the shelf life of the food or food products, food quality measurements, and food processing operations.
Image Credits: Surasak_Photo / Shutterstock.com
Deviations from the optimal moisture content can severely impact numerous qualities of the food product, which can have implications not only on product quality but also on its safety. For this reason, moisture content analysis has become a key component of the food industry.
What does moisture content mean?
Moisture content refers to the number of water molecules that become incorporated into a food product. Moisture can enter into a product in a number of ways, it could be related to the production method of the product, the atmospheric moisture in the food production area, the packaging method of the product, or it can be related to the method of food storage.
Why is moisture analysis important in the food industry?
Moisture content has a lot to do with a food product’s characteristics, including its physical appearance (shape, color, etc.), texture, taste, weight (which can impact the cost) in addition to factors that affect the product’s shelf-life, freshness, quality, and resistance to bacterial contamination.
Excess water in a food product can cause an increase in the rate of microbial growth, which can not only spoil a product before it reaches the shelves but could also decrease the length of time it can stay fresh for. This has a significant impact on whether or not the products reach their advertised use-by date.
All of these factors influence the success of a food producer. Maintaining specific characteristics of a product is essential to customer satisfaction, loyalty, and ultimately revenue and profits.
Each factor that can be influenced by moisture content is reviewed below, giving relevance to how it impacts the food industry.
1. Legal and labeling requirements
There is legislation surrounding certain food products that puts specific limitations on how much moisture content can legally be present in the product. Cheddar cheese, for example, is one such controlled food product, and it is allowed to have no more than 40% of moisture content. For food producers of controlled products, moisture analysis is essential to meet legal requirements.
2. Shelf life
Shelf life is important because it informs consumers of when food is safe to consume. Moisture content influences shelf life because increased water in a product raises its susceptibility to microbes, which can rot and damage the food. Therefore, maintaining a known level of moisture in a product allows producers to accurately estimate the shelf life of a product, helping to keep consumers safe from consuming spoiled food.
3. Food quality
As discussed above, moisture content can have dramatic effects on the quality of a food product. It can impact the taste, texture, and look of a product. Manufacturers seek to keep products as consistent as possible to ensure the same quality, and to avoid waste. Controlling for moisture content plays a key role here.
4. Food processing operations
Too much moisture in food products can cause condensation in machinery used to processes the food items. This can lead to corrosion or blockages, which can result in unplanned downtime while machines are fixed. This can slow down production and can increase the cost of production due to wasted hours.
Therefore, carrying out an analysis of moisture content using a robust and accurate method is essential for food production companies. Failure to observe this stage of the food production process could cause a negative impact on product quality, safety, and profitability.
How is moisture content measured?
There are various methods of measuring moisture content in food:
A high-boiling point solvent is mixed with the food sample and then distilled off to obtain a quantity of water. The drawback of this method is that it can potentially cause adverse chemical reactions.
2. Dielectric method
This method involves exploiting the electrical properties of water to measure moisture content. The change in electrical current passed through a sample is measured in order to obtain a measurement. This method is often used as a control process to ensure that known moisture content is maintained.
Hydrometry is a method that obtains a measure of moisture content by measuring the specific gravity of a food sample. This technique is limited to use with certain food types, such as beverages, salt brines, and sugar solutions.
4. Infrared spectroscopy
This method determines moisture content by measuring the absorption of radiation by molecules in a food sample. The amount of energy that is reflected or absorbed is a key indicator of how much water is in the sample.
Measuring the refractive index in a food sample can give a measure of moisture content. However, it is most often used in determining the sugar concentration of food samples.
6. Chemical analysis
Foods with a low moisture content benefit from the chemical analysis method. The drawback of the technique is that it requires concentrated chemicals that have characteristic strong smells.
7. Oven drying
The final method is oven drying, where a food sample is weighed before and after it is dried in an oven. This change in weight indicates the level of moisture that was contained in the sample. However, due to the lengthy process of drying out, which can take up to 18 hours, it is often only used for the establishment of a reference point.
The analysis of moisture content is essential to the food industry to control for the quality of the food, as well as the shelf life, in addition to helping food manufacture companies adhere to legal and labeling requirements.
Further, cautionary moisture content analysis can serve to protect their revenue and profits by ensuring product consistency and safety, minimizing waste, and reducing unplanned downtime of food production machinery.
Isengard, H. (2001). Water content, one of the most important properties of food. Food Control, 12(7), pp.395-400. https://www.sciencedirect.com/science/article/pii/S0956713501000433
Ismail, B. (2017). Ash Content Determination. Food Analysis Laboratory Manual, pp.117-119.
Land, K. and Steinberg, M. (1980). Calculation of moisture content of a formulated food system to any given water activity. Journal of Food Science, 45(5), pp.1228-1230. onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2621.1980.tb06527.x