Ingredients used in any formulation are important regardless of the finished product, but the types and amounts of ingredients used in formulating high-protein ice cream are particularly critical in achieving the desired outcome.
This post is the first of two which summarizes key points from a webinar titled “Formulating Excellent Quality, High-Protein Ice Cream.” Part 1 provides a detailed, technical presentation on ice cream formulation; the role of various ingredient types in achieving required functionality; and problems often associated with designing high-protein ice cream as well as solutions to these problems. Part 2 focuses on optimizing high protein ice cream with Idaho Milk Products’ IdaPlus1085, a functional reduced-calcium milk protein concentrate (MPC) that provides the functionality needed to create top quality, high-protein ice cream. Webinar presenters included Joe Marshall, Food Scientist, Socius Ingredients and in Part 2, Kumar Tammineedi, Senior R&D Scientist, Idaho Milk Products and Venkat Sunkesula, Ph.D., Associate Director of Research & Technical Services, Idaho Milk Products.
Ice Cream is a 4-phase structure, noted Socius Ingredients’ Joe Marshall. It is made up of (1) Serum: Unfrozen water plus all soluble components (i.e., whey, casein, sugar, salt, stabilizers, flavor); (2) Fat; (3) Air Cells and (4) Frozen Water. After processing [See Sidebar: Ice Cream Procedure], the ice cream becomes a 3-phase emulsion of fat and air dispersed in a continuous water phase, explained Marshall.
Harsh conditions during processing distribution and storage create the potential for quality issues—affecting both sensory attributes as well as physical ones. As such, a formulations’ ingredient functionalities play a critical role in creating a high-quality finished product that will remain so throughout its shelflife. These functionalities include hydration, freezing point depression, stabilization (e.g., air cell stability, shape retention, etc.), emulsification, partial coalescence of fat globules and heat shock resistance, among others.
Although used in small quantities, stabilizers (e.g., gums) can have large ramifications to sensory and physical properties of ice cream, noted Marshall. Sensory attributes include creaminess, body and thickness; flavor release; and iciness/ice perception. Physical properties include heat shock resistance—preventing ice crystals from coalescing & forming bigger ice crystals, resulting in freezer burn; altitude shock resistance—deterring atmospheric pressure changes from affecting the pressure within the ice cream’s air cells; and structural integrity— having optimal meltdown properties.
Emulsifiers also play an important part in ice cream’s stability, as does partial coalescence. Emulsifiers and proteins, with their hydrophilic and hydrophobic ends, coat the outside of fat globules as they are sheared during whipping. But, because protein molecules are very large, there’s a steric hindrance causing fat molecules to collide and bounce off one another, explained Marshall.
As the molecules of emulsifiers are much smaller than that of protein, fat molecules will still collide, but also maintain their globular shape and stick together. This is called partial coalescence. While proteins and emulsifiers compete for the interface on fat droplets to some extent, emulsifiers usually win out, noted Marshall. “You should have enough protein displaced by the emulsifier to have that connection (i.e., partial coalescence) take place,” he added.
Partial coalescence helps the ice cream maintain its shape and provides air cell stability and heat shock resistance. “Partial coalescence is very important in ice cream structure,” said Marshall. “It’s really the scaffolding that makes up the ice cream and gives it its integrity.”
Attributes of High-Protein Ice Cream: Problems & Solutions
Protein content of standard ice cream is 3-4%, which generally comes from skim milk powder and cream. High protein ice cream is anything that exceeds the level of standard ice cream, but typically ranges from 7-15% protein, noted Marshall, with protein fortification usually coming from dairy protein concentrates or other non-dairy sources.
“High-protein ice creams are striving to be more nutritious by maximizing protein, while minimizing fat and sugar,” said Marshall. In effect, these products are typically low calorie, zero or low sugar and lower in fat.
High-protein ice creams are subject to various problems during processing and throughout shelflife. Processing issues involving foaming and thickness can occur, for instance. Proteins act as foaming agents, so when the protein content is higher, foam (i.e., trapped air) needs to be minimized during mixing, prior to pasteurization and homogenization. “Air in the mix can lead to pumping issues and irregular heating,” explained Marshall. “Cold-water activated gums (e.g., guar, xanthan, etc.) create a viscous mix making it very difficult to release foam once formed,” he added.
As high-protein ice cream tends to be lower in sugar and sugar is one of the greatest contributing factors to freezing point depression, issues related to hardness can occur. As Marshall illustrated, ‘there is a large portion of water in ice cream that remains liquid, but it contains all soluble components—sugar being one of those soluble components. If you don’t have low freezing point depression, your ice cream is going to turn into a rock.”
Shrinkage over time, where the ice cream pulls away from the outside of the container, is a complex issue involving air cell stability and thermal/altitude shock. Protein type and concentration play a large role in shrinkage. Poor foam stability leads to the development of a lot of air, resulting in potential shrinkage, noted Tammineedi. While this issue can occur in any type of ice cream, it is more often associated with high-protein formulations.
Proteins can affect sensory issues as well, contributing off flavors and viscosity—creating a thick, soggy, gummy product. “You don’t want to have to ‘chew’ the ice cream, as we call it,” said Marshall. “Optimizing the type of protein, sweetness, flavor and fat level can help mitigate any off notes associated with the protein,” he added.
A variety of solutions are available to offset other inherent problems associated with high-protein ice cream, aside from off-flavor issues previously mentioned. Regarding foaming and viscosity, heat-activated gums such as locust bean and tamarind seed gums maintain low viscosity and will only increase in thickness during the pasteurization step.
Use of an antifoaming agent can help release foam. Time and gravity will eventually cause the air to collapse on itself. “Give 30 minutes for hydration but give it time after that to ensure the mix is as dense as possible without trapped air,” recommended Marshall.
Proteins not only need to be well blended and hydrated properly, but also have adequate heat stability. Different proteins have different heat tolerances. “Concentration is also important. Make sure you don’t have a spike in viscosity during processing, as this can lead to blockage in the press, shutting down the whole system,” emphasized Marshall.
As freezing point depression is inversely related to molecular weight (M.W.), low M.W. molecules such as sugar, fructose and sugar alcohols “do the heavy lifting regarding freezing point depression,” said Marshall. Erythritol, allulose and xylitol not only aid in freezing point depression in low-calorie or reduced sugar formulations, but help with sensory attributes, like sweetness.
Locust bean and tamarind seed gums, previously mentioned in forming proper viscosity, also help stabilize air cells through the cryo-gelation process upon freezing. “The cryogel spans the entire serum network, bolstering stability so air cells don’t shrink over time, said Marshall. These gums also provide the desired melt characteristics, giving better shape retention during shelflife and help prevent thermal or altitude shock.
Click here to view Part 2 of the webinar summary on “Formulating Excellent Quality, High-Protein Ice Cream,” which focuses on the use of IdaPlus 1085, a functional MPC developed specifically for the creation of optimal high protein ice creams.
Ice Cream Formulation & Processing Procedure
|Typical Ice Cream Formula|
|Skim Milk (MSNF)||40-70%|
- Create the Mix
- Mix all dry ingredients.
- Make sure the mix is homogeneous (i.e., without fisheyes).
- Slowly add mix to skim milk in hot water bath at 45°C.
- Mix for 30 minutes. Make sure everything is well hydrated.
- Pasteurize using Standard HTST Process (assuming downstream homogenization setup)
- Heat at 176°F (80°C) for 30 sec (kills pathogenic bacteria; melts fat & emulsifiers; allows for proper homogenization; activates any hot water activated gums).
- Homogenize at 150/50 bar (creates more uniform emulsion & creamier product; prevents fat from creaming out during aging).
- Leave at 4°C (39°F) overnight or a minimum of 4hrs (allows time for full hydration of powders [i.e., protein & hydrocolloids]; emulsifiers to displace protein on the fat/water interface, which helps aid in partial coalescence; and for fat to crystallize).
- Weight out ice cream base
- Take sample to test for viscosity & stability.
- Add flavor/inclusions.
- Pour base into freezer and activate (Make sure enough air is whipped into base to achieve desired overrun).
- After desired freezing time, change to “dispense” function & fill containers.
- Hard Freeze
- Place ice into -60°C (-76°F) Freezer for 2hrs. (prevents Ostwald ripening where small particles dissolve, while larger particles form).
- Transfer to Standard Freezer