Raising the foam of plant-based beverages

An increasing number of consumers are seeking plant-based alternatives that meet the functionality and flavour aspects of their animal-based counterparts, particularly when it comes to plant-based milk products. For example, a high-performing plant-based barista beverage is demanded by consumers due to the recent rapid growth of specialty foamed coffee beverages. However, there is a major functionality gap between dairy and plant-based commercial barista offerings. The structure of dairy proteins allows for formation of stable, pourable microfoams that are perceived as ‘creamy’ and can carry flavour without imparting off notes or textures.

Meeting the functionality of dairy proteins with plant-based proteins is a major challenge, considering how structurally different plant seed storage proteins are from dairy proteins. Additionally, dairy proteins are generally more stable against aggregation and other quality defects at the pH of coffee compared to plant-based proteins.

Given these challenges, an approach to identify and quantify the functionality gaps between dairy and commercial plant-based milk products has been established via functionality mapping. Using barista-style non-dairy milk as a core example, a mapping approach was applied, then leveraged to understand from a structure-function standpoint why plant-based commercial offerings are functionally inferior to dairy; identify the quantitative targets for bridging the gap; and guide the creation of a winning plant-based solution.

Tracking patterns in how different formulations perform allows such an approach to have the highest level of success in developing a novel ingredient system for plant-based dairy beverage in general, and barista-style dairy beverage functionality in particular. It also demonstrates how utilizing a functionality mapping approach can progress ingredient structure-function understanding and catalyze the development of novel plant-based food and beverage applications.

Meeting consumer plant-based demands

The steady growth in sales of plant-based milk continues to be strong and already is closing in on US$3 billion annually at a double-digit CAGR of 11 per cent, according to research conducted by the marketing group SPINS conducted for 52 weeks, ending January 2023. Multiple reasons for this growth include overall consumer interest toward plant-based/healthier diets, sustainability, and animal welfare concerns.

In fact, as SPINS included in its report, plant-based milk currently makes up some 15 per cent of the overall retail milk sales market. But merely being plant-based isn’t enough: Consumers need plant-based milk alternatives to meet the functionality, taste, and nutrition of their dairy-based counterparts. As the non-dairy milk market grows, products must evolve to meet consumer needs.

Dairy milk is typically perceived as the benchmark standard when it comes to improving taste, nutrition, and functionality of a plant-based replacer. And functionality is especially important when it comes to crafting plant-based versions of so-called ‘barista milk.’ With the rise of specialty foamed coffee beverages, consumers seek strong foaming functionality as dairy milk.

Determining and measuring the texture gap

When it comes to popular barista milk, there is a major gap to fill between plant-based versions and the dairy ones being mimicked. The plant-based versions must overcome the common challenges of creating and holding a foam, having a smooth and creamy foam texture, and avoiding formation of particulates and separation in hot and/or acidic beverages, all while carrying perfect flavour.

The protein structure and composition of dairy components are perfectly designed for high water-solubility, leading to a smooth and stable system when added to coffee. Moreover, dairy protein structure and composition allow for strong foaming capacity and stability, such that their barista milk attain and maintain foam volume and quality over time.

Issues challenging plant-based dairy analogs, especially those of plant-based barista milk, include low water-solubility of certain components. This is because plant proteins are designed to pack tightly together in mostly dry environments—the protein molecules are typically large and highly hydrophobic. This lower solubility and marked structural and compositional differences translate to weaker foaming properties, poor foam height, poor foam quality, agglomeration/aggregation, and particle settling — the plant-based alternatives clump and separate when exposed to the heat and acid of a coffee or tea beverage.

However, these challenges go beyond barista milk and extend to all plant-based versions of animal-based dairy products. By approaching the advancement of plant-based ingredient structure-function understanding, it is possible to move closer to the animal-based ‘gold standards’ and develop analogs that effectively meet them with full organoleptic experience and functionality.

Bridging the gap with functionality mapping

To bridge the plant-based dairy/animal-based dairy ‘texture gap,’  it is important to first identify the key functionalities that must be met. Then, developers would design a methodology to adequately measure functionality, and map current plant-based functionality vs. animal-based gold standards to quantify key components of the  starting point and the desired end point. Once these processes are in place, it is possible to leverage that mapping into a hypothesis-based testing that drives development of the solution.

Using barista milk as an example, as described above the key  functionalities are: generation and stabilization of foam, having a smooth and creamy microfoam texture, and avoiding the agglomeration, aggregation, and particle settling that causes separation and textural challenges in hot/acidic beverages. And, of course, the solution must deliver the full promised flavours, without any off notes or bitterness that sometimes can accompany plant-based proteins. For example, when it comes to barista milk, the methodology developed for creating a plant-based version would focus on foam generation. This would include initial foam volume (foam capacity), foam stability (via measurement of liquid drainage volume over time), and finally its pourability, foam bubble size, and stability when actually poured over a true hot espresso coffee beverage.

Focusing in on foaming capacity and stability as an example, after relevant methodology is developed to characterize these functionalities, functionality mapping of the current commercial landscape would characterize the gap between plant-based and dairy. This could include characterizing and comparing foam volume and stability of multiple bases—almond, oat, pea, and true dairy milk—in both plain dairy milk and barista-style milk. This functionality mapping would reveal trends in functionality by base, protein content, presence of particular ingredients, etc. to characterize the landscape. Additionally, this would allow for quantification of dairy targets and the gap between commercial plant-based and dairy options.

Adjusting levers to unlock solutions

Adopting a multi-ingredient system approach to meet the performance targets of dairy with a plant-based milk product centres on the functional needs of the final product. This then requires establishing proposed structures to meet those functional needs. In the case of plant-based milk analogs, two components to a foaming solution that could work in harmony are protein and hydrocolloid. Certain plant-based proteins can provide foaming capacity depending on their structure and composition, whereas hydrocolloids can provide foaming stability to address functionality gaps between plant-based and dairy. Functionality mapping of different protein-hydrocolloid systems via hypothesis-driven testing can build the ingredient structure-function understanding that unlocks a plant-based barista milk solution. To do this, a proper design of experiments testing ranges of protein and hydrocolloid usage levels allow for tracking of impact of these levers on functionality, and optimization of these two components to meet the dairy-based product functionality target.

Answering key questions

Through the outlined methods of functionality mapping, the approach to crafting consumer-preferred plant-based dairy replacers and analogs can be successfully established. This involves first focusing on three key questions: Have the functionalities that matter to consumers been properly identified? Are the functional performance parameters being measured in a relevant way? And have the gaps between the starting point and the end goal been correctly identified and characterized?

In identifying and quantifying functionality and performance gaps between dairy and plant-based milk, including barista beverages, such a mapping approach can be leveraged to enhance ingredient structure-function understanding and guide the development of a novel plant-based solution.

Based in Westchester, Ill., Alexandra Hall, PhD, is an analytical characterization and texture scientist at Ingredion.

This article was originally published in the April/May 2024 issue of Food in Canada.