Physicochemical and Sensory Properties of Non-Dairy Milk Alternatives

CHAPTER ONE

1.1 Background to the Study

Non-dairy milk alternatives have grown increasingly popular over the past decade. Rising awareness of lactose intolerance, milk allergies, vegan diets, and environmental sustainability has encouraged many consumers to seek plant-based substitutes for traditional cow’s milk. Products such as soy milk, almond milk, coconut milk, oat milk, rice milk, and peanut milk are now widely available in supermarkets and local markets across the world (Singh et al., 2020). These alternatives offer not only nutritional benefits but also functional properties suitable for cooking, baking, and beverage use.

Non-dairy milks are typically produced by soaking, grinding, and filtering plant materials to obtain a liquid extract. The resulting beverage contains a mixture of proteins, fats, carbohydrates, vitamins, and minerals, depending on the plant source. For example, soy milk is rich in protein and phytochemicals, almond milk contains healthy fats and vitamin E, while oat milk is high in fibre and β-glucans (Vanga & Raghavan, 2018). Because of their diverse nutritional profiles, non-dairy milks serve different dietary needs.

However, non-dairy milk alternatives differ from cow’s milk in their physicochemical and sensory characteristics. Physicochemical properties such as pH, viscosity, total solids, colour, protein content, and stability influence how these beverages behave during processing and storage. For example, low protein levels can cause poor emulsification, while high starch content may lead to thick textures. These variations affect consumer acceptability and limit the applications of certain plant-based milks.

Sensory properties—such as taste, aroma, mouthfeel, and appearance—strongly influence consumer preference. Some plant-based milks have desirable creamy textures and mild flavours, while others carry beany, nutty, or grassy notes that may reduce acceptability. For instance, soy milk’s characteristic beany flavour often limits its appeal among new consumers (Sethi et al., 2016). On the other hand, coconut and almond milk are often preferred for their pleasant aroma and flavour. Therefore, evaluating sensory attributes is essential for improving product quality.

Processing techniques also affect physicochemical and sensory properties. Heating, homogenisation, and fortification can alter flavour, nutritional composition, and stability. Manufacturers often add stabilisers, emulsifiers, sweeteners, or flavourings to improve mouthfeel and consumer appeal. Despite this, many small-scale processors rely on simple extraction methods that may produce inconsistent quality.

With increasing global demand for plant-based foods, the non-dairy milk market continues to expand. Consumers seek healthier, environmentally friendly, and allergen-free options. However, not all plant-based milks meet quality expectations. Many products sediment quickly, separate during storage, or lack desirable sensory properties. These challenges highlight the need for scientific evaluation of their physicochemical and sensory characteristics.

Additionally, nutritional awareness has grown. Consumers want products that offer functional benefits, such as fibre, antioxidants, or low cholesterol levels. Understanding the properties of different milk alternatives enables manufacturers to create products that meet these expectations while maintaining high sensory appeal.

Given these developments, it is important to investigate the physicochemical and sensory properties of selected non-dairy milk alternatives. This study examines these properties to inform production improvements, enhance consumer acceptability, and support innovation in the plant-based beverage sector.

1.2 Statement of the Problem

Despite the increasing popularity of non-dairy milk alternatives, product quality varies greatly. Many plant-based beverages on the market exhibit issues such as sedimentation, phase separation, inconsistent viscosity, and undesirable flavours. These quality defects reduce consumer acceptance and limit commercial success.

Furthermore, small-scale producers often lack the technical knowledge required to produce stable and appealing milk alternatives. Without understanding the physicochemical behaviour of plant-based milks, they struggle to optimise extraction methods or improve formulation. As a result, their products may differ in texture, colour, and taste from batch to batch.

Another challenge is the limited scientific research on locally sourced plant materials used to produce milk alternatives. Most available studies focus on globally popular products such as soy and almond milk. Less attention is given to indigenous sources such as tiger nut, coconut, sesame, African walnut, or groundnut. These materials have unique functional and sensory properties that require proper characterisation.

Additionally, consumer preferences vary widely across cultures and regions. A beverage acceptable in one area may be less preferred in another due to differences in flavour expectations, dietary habits, or cultural preferences. Without sensory evaluation, producers cannot determine which plant-based milk alternatives appeal to local consumers.

This study seeks to address these gaps by examining both physicochemical and sensory properties of selected non-dairy milk alternatives.

1.3 Aim and Objectives of the Study

The aim of this study is to evaluate the physicochemical and sensory properties of selected non-dairy milk alternatives.

The specific objectives are to:

1. Determine the physicochemical characteristics (pH, viscosity, total solids, colour, and protein content) of selected milk alternatives.

2. Assess the sensory attributes of the beverages.

3. Compare the properties of different plant-based milks.

4. Identify factors influencing acceptability among consumers.

5. Recommend improvements for product formulation and processing.

1.4 Research Questions

The study seeks to answer the following questions:

1. What are the key physicochemical properties of the selected non-dairy milk alternatives?

2. How do sensory attributes vary across different milk types?

3. Which milk alternatives demonstrate the highest consumer acceptability?

4. What processing or formulation factors influence physicochemical stability?

5. How can product quality and acceptability be improved?

1.5 Significance of the Study

This study provides several contributions. First, it enhances understanding of the nutritional, functional, and sensory characteristics of plant-based milk alternatives. This information is valuable for manufacturers seeking to improve product quality.

Second, the study supports small-scale producers who wish to enter the growing plant-based market. By identifying key quality parameters, producers can develop more stable and desirable products.

Third, the findings benefit consumers by promoting the availability of safer, more nutritious, and better-tasting milk alternatives. This aligns with global shifts towards healthier diets and environmentally sustainable food choices.

Fourth, the research contributes academically to the fields of food science, nutrition, and product development. It provides data that future researchers can use to improve extraction techniques, optimise formulations, or explore new plant sources.

Finally, the study promotes the utilisation of locally available plant materials. This supports agricultural development, reduces dependence on imported ingredients, and strengthens local economies.

1.6 Scope of the Study

The study focuses on selected plant-based milk alternatives such as soy milk, coconut milk, almond milk, or tiger nut milk. It examines physicochemical parameters and conducts sensory evaluation using trained or semi-trained panellists. It does not assess long-term storage stability, microbiological safety, or the effects of extensive fortification.

1.7 Operational Definition of Terms

• Non-Dairy Milk: A beverage made by extracting liquid from plant sources as an alternative to animal milk.

• Physicochemical Properties: Measurable characteristics of a beverage such as pH, viscosity, and colour.

• Sensory Properties: Attributes related to taste, aroma, mouthfeel, and appearance.

• Sedimentation: The settling of solid particles at the bottom of a liquid.

• Plant-Based Beverage: A liquid drink produced from plant materials.