Friday, October 19, 2018

Managing Moisture in Dairy Foods: A critical part of the innovation process

Pack Expo 2018 took place this week in Chicago. I spent some time talking with dairy industry suppliers to learn what are the biggest issues and obstacles they face when packaging new dairy product concepts. The number-one complaint was unrealistic expectations of product consistency throughout shelf life.

A pouch supplier explained that syneresis may occur in yogurt pouches just like it does in cups. When that first squirt into a toddler’s mouth is liquid and not yogurt, mom and dad can expect some spitting and complaining. That’s a sure way to lose a customer.

We talked about the larger pouches now housing sour cream and condiment Greek yogurt. No one wants that first squeeze to be what often occurs with ketchup and mustard, red or yellow liquid, respectively.

And no one wants to see a layer of whey in those attractive glass jars holding premium yogurt, puddings and other dairy desserts.

Smaller containers of ice cream—from pints to 4-ounce cups—have more exposed surface area than larger multi-serve containers. During distribution, product may undergo multiple freeze-thaw cycles, which leads to ice crystal development and eventually freezer burn. Better managing of moisture slows the onset of this defect.

If you are facing any of these issues, below you will find an overview on managing moisture. And, once you understand how to manage it, then it’s time to explore how to create unique textures by manipulating moisture.

That’s what you find at The Republic of Booza, a new ice cream store that opened this summer in the Williamsburg neighborhood in Brooklyn, New York. I had the opportunity to try it out when in town for the Summer Fancy Food Show.

Booza is a frozen dairy-based dessert widely known in the Eastern Mediterranean region called the Levant, which encompasses Syria, Lebanon, Israel, Turkey and Greece. It’s a denser, creamier, more-elastic ice cream—somewhat like taffy--than what Americans know.

It is made with the ancient ingredient sahlab, or ground orchid root, and mastic, a resin. These moisture-managing ingredients are added to milk and mixed in a freezer drum. At the Republic of Booza, this takes place with a three-foot wooden pestle and the ice cream is stretched by hand.

The product has the unique ability to resist melting, lending itself to almost being a chewy frozen treat. This format also makes it an excellent delivery vehicle for unique flavors. Original Qashta is a candied cream flavor. Other global flavors on the menu are Coconut Matcha, Horchata de Chufa, Mango-Tajin, Mint Tahini Chip, Red Miso, Saffron Peppercorn and Sichuan White Chocolate. The menu includes familiar favorites, too, such as Chocolate, Pistachio, Salted Caramel, Strawberry and Vanilla, as well as some experimental combinations like Salted Oreo and Bloody Mary.

photo source: The Republic of Booza

Managing Moisture 101
(This is adapted from an article I wrote years ago. You can read it in its entirety HERE.)

Product developers willing to explore technologies that manipulate moisture often discover unique and, typically, quite economical opportunities for innovative product development. This is because water, the most abundant, yet often frequently overlooked constituent in the food supply, is basically a free ingredient that impacts structure and increases yield, all for zero calories.

What product developers cannot afford to overlook is careful management of moisture in commercially manufactured foods, as too much or too little, or not being in the right matrix, can be detrimental to product quality and safety. This is very true for highly perishable refrigerated and frozen dairy foods.

Water content influences a foods structure, appearance, taste and even susceptibility to degradation. Water is used as an ingredient in many food formulations, and most food ingredients also contain noteworthy amounts of water. This must be carefully considered when attempting to manage moisture. For example, butter is approximately 17% water, whole eggs are more than three-fourths water, and wheat flour is about 12% water. The water content of inclusions and fruit ingredients must not be overlooked.

With moisture coming from so many sources, product developers must make sure water stays where it is supposed to be and does what it is supposed to do. Sometimes this requires taking the necessary steps to prevent evaporation, while other times the goal is to prevent the food from absorbing moisture from the surroundings. When dealing with a multicomponent prepared food, the issue might be moisture migration, or the prevention of water seeping from one component to another. Still another challenge is making sure the water is not available for the growth of undesirable living organisms.

Managing the water content of food products is necessary for efficient processing, packaging selection, and distribution and storage conditions. Before one can manage moisture, however, one must know how much water a foodstuff contains. In principle, the moisture content of a food can be determined by measuring the number or mass of water molecules present in a known mass of sample. However, for the most part, it is challenging to directly measure the number of water molecules present in a sample because too many molecules are involved. Thus, sometimes moisture contents are based on calculations using predetermined water contents of known food ingredients.

There are also various analytical techniques, ranging from vacuum to microwave ovens. The technology must be able to distinguish water from other components in the food matrix. This can be challenging, because despite having the same chemical formula (H2O), the water molecules in a food may be present in any of four varieties of molecular environments, depending on their interaction with the surrounding molecules, and thus they possess different physiochemical properties.

The most basic form is as bulk water, which is when water is free from any other constituents. Each water molecule is surrounded by other water molecules and its physicochemical properties resemble pure water.

Trapped water, also known as capillary water, is moisture held in narrow channels between certain food components. This trapped water is surrounded by a physical barrier that prevents the water molecules from easily escaping, such as all that water in a raspberry. This type of water tends to have physicochemical properties similar to that of bulk water.

Physically bound water molecules are in molecular contact with other food constituents, such as proteins, carbohydrates and minerals. These food constituents bind with water, creating a system that no longer recognizes the water as free bulk water. The bonds between water molecules and these constituents are quite different from water-water bonds.

Finally, there are chemically bound water molecules. This is when water molecules present in a food are chemically bonded to other molecules as water of crystallization or as hydrates. These bonds can be very strong.

Although the water content of a food is expressed as a percent, this number does not reflect how the water exists in the food. Food product developers must consider all four forms of water when trying to manage moisture. Further, commercially manufactured foods may contain water in different physical states, such as gas, liquid or solid. This is the reason why moisture management is necessary and can be quite challenging.

In addition to quantifying water content, product developers must consider water activity (aw), which describes the energy status or the escaping tendency of the water in a sample. Water activity is often described in terms of the amount of bound water and free water. Although these terms make the concept of water activity somewhat easier to conceptualize, the reality is that all water in food is somewhat bound; after all, it is contained in the food. Thus, water activity is a measure of how tightly water is bound and relates to the work required to remove water from the system. Water activity predicts safety and stability with respect to microbial growth, chemical and biochemical reaction rates, and various physical properties.

Moisture-management systems vary by application. Factors to consider include product storage conditions (ambient, frozen and refrigerated), the potential of temperature extremes, shelf-life expectations, and the overall objective of keeping moisture in, out or contained in a product.

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