Shelf life is an established time under a defined set of conditions during which a product is acceptable for use. The three largest variables affecting shelf life are: product characteristics, packaging materials and storage conditions. The table below shows typical shelf life guidelines for dry dairy ingredients in bulk or bag packaging under ideal storage and shipping conditions (maximum temperatures of 25˚C with a maximum relative humidity of 65%). In general, though, dairy ingredients manufactured, packaged and stored under ideal conditions can remain free flowing and without color change for periods longer than stated in these guidelines.

Typical Shelf Life Guidelines for Dairy Ingredients
Stored at 25˚C Maximum and 65% Relative Humidity Maximum

Dairy Ingredient	Shelf Life
Lactose	12 Months
Skim Milk Powder (SMP)	12-18 Months
Dry Sweet Whey (DSW)	6-12 Months
Whey Protein Concentrate 34% (WPC34)	12 Months
Whey Protein Concentrate 80% (WPC80)	12 Months
Whey Protein Isolate (WPI)	12 Months

The information below is designed to help you select the right dairy ingredient for your application and maximize product quality prior to use:

• Guide to Maximizing Shelf Life
• Packaging Guidelines for Dairy Ingredients
• Dairy Ingredient Quality: Potential Changes During Storage

Guide to Maximizing Shelf Life

Packaging

• Moisture resistant packaging may help minimize moisture uptake and maintain water activity (A_w) levels at or below suggested levels (<0.24) to help minimize product changes during storage.
• The combination of a 3-4 ply multi-wall Kraft paper bag and 3-4 mil thickness LDPE bag liner offers good product protection during storage and handling.
• Modified Atmosphere Packaging (MAP) has been shown to positively impact shelf life. In this process, nitrogen or another gas or gas mixture is used to replace oxygen in the package headspace. Note: This technology is not widely available in the United States and is being further developed.

Storage & Handling

• Store product in constant, controlled temperatures at or below 25˚C when possible.
• Avoid temperature fluctuation at higher temperatures.
• Use product according to the date of manufacture, always using the oldest product first.
• Store product in dry areas; avoid storage at high or extreme humidity levels, i.e. above 65%.
• Store product away from strong odors and contaminates.
• Prevent damage during handling to avoid product contamination. Discard damaged bags and product.

Product specific information is available directly from the supplier and may vary depending upon product type, packaging material and processing conditions. U.S. dairy ingredient suppliers are an excellent resource for information related to product formulations and selecting the right ingredient for a specific application. Many suppliers have trained research and development (R&D) experts available to assist customers as needed. Click here to locate a U.S. supplier.

Packaging Guidelines for Dairy Products

Dairy ingredients must be packaged properly to preserve flavor and physical characteristics. The best packaging for dairy products will minimize air and moisture entry into the product.

Several types of packaging are approved for dairy powders. The more durable and most frequently used type is a multi-wall Kraft paper bag with an inner low density polyethylene (LDPE) bag liner, both of which are heat sealed. This type of bag construction is referred to as a "bag within a bag". Packaging differs in the thickness and number of layers of Kraft paper and the thickness and material of the bag liner. The combination of a 3-4 ply multi-wall Kraft paper bag and 3-4 mil thickness LDPE bag liner offers good protection during storage and handling. The LDPE bag liners have vents to allow air to escape from the bag. This prevents rupture during handling and storage. There are different technologies available to reduce the amount of air and moisture getting into the dry dairy product through these vents; the technology varies by bag manufacturer.

The U.S. Department of Agriculture (USDA) specifies bag construction for nonfat dry milk/skim milk powder for use in food assistance programs in their publication, Announcement Dairy 6. The packaging is to be the equivalent of a 3-ply Kraft paper with a total basis weight of 81.6 kg (180 lbs) and a LDPE inner liner thickness of at least 3 mil. The maximum water-vapor transmission of the film at 90 - 95 percent relative humidity at a temperature of 37.8°C shall be 0.45 g per 645 square cm in 24 hours.  

Quality Changes During Storage

Ideal storage conditions for dry dairy products are temperatures below 25°C with a relative humidity below 65%. The greatest loss of product quality during storage is often the result of moisture uptake by the powder which may result in chemical, physical and bacteriological changes.  The lactose in dairy ingredients is hygroscopic and readily takes up water. Packaging that is more robust and water-resistant can help extend shelf life, especially in more extreme environments. If you have any questions regarding the quality and/or acceptability of a particular product please contact your supplier.

Click any of the areas listed below for more information on quality changes during the storage of dairy ingredients.

Color/Browning
Clumping
Flavor
Functionality
Hardening
Nutritional
Powder Structure

Color/Browning

Browning occurs when lactose and protein interact at elevated storage temperatures (i.e. above 35°C) through a complex series of reactions called the Maillard reaction. For some products, such as baked goods, the color and flavor changes associated with browning are highly desirable. In other situations the Maillard reaction may lead to a loss of quality during storage. Variables that influence the Maillard reaction include: raw material composition, method of manufacture, processing and storage temperatures, pH, water activity, oxygen and the presence of lactose and other sugars. The following are potential effects of the Maillard reaction: color changes, flavor changes, changes in water activity, pH decrease, increased antioxidant activity, reduced solubility and loss of lysine.

Increased temperatures will increase the Maillard reaction with fluctuating temperatures causing greater browning than constant temperatures. Decreases in pH may also increase browning, although this effect depends on the water activity (A_w) of the powder. Another factor affecting browning is the ratio of lactose to protein in the product. In general, the higher the lactose content, the faster the Maillard reaction. Reaction rates for DSW, WPC34 and SMP tend to be higher than for whey protein concentrates with 60% or more protein.

Clumping

This is typically caused when the lactose component in a dry dairy ingredient begins to absorb moisture. Ingredients with higher lactose content will be affected more than those with lower lactose levels.

Flavor

Dry dairy products are known for having a neutral, mild dairy flavor. Storage at high temperatures and high relative humidity may increase the potential development of off-flavors. In many cases, significant changes in product flow and solubility will occur before any changes in flavor and aroma become evident. Flavor changes develop more quickly in agglomerated or "instant" ingredients.

Functionality

The solubility, foaming and emulsification properties of dairy ingredients are fairly stable during storage. Changes in solubility may occur and are most often related to color changes, such as browning.

Hardening

This is typically caused when a dry dairy product has been exposed to high storage temperatures and high storage relative humidity (>85%) for an extended period of time. The amount of time before hardening occurs will vary depending on the specific storage conditions, product type and packaging.

Nutritional

Storage at higher temperatures may reduce the amount of the amino acid lysine in the product. Exposure to moisture may increase the amount of loss.

Powder Structure

Powders with higher lactose levels can have the following undesirable changes during storage:  stickiness and caking, lactose crystallization, lipid release from powder particles, increased browning; and lipid oxidation. If dry whey ingredients become caked they can be ground with the resulting powder remaining free flowing unless exposed to high humidity.