1.1 Introduction
Tiger nut milk is a plant-based beverage made from the tubers of Cyperus esculentus, known for its creamy texture, slightly sweet taste, and nutritional benefits, including dietary fiber, unsaturated fatty acids, and essential minerals (Ahmed et al., 2018). Tiger nut milk, derived from the tubers of Cyperus esculentus, has garnered attention due to its nutritional value, rich flavor, and suitability for individuals with lactose intolerance. It serves as a non-dairy milk alternative that is high in fiber, essential fatty acids, and vitamins. However, it is prone to microbial spoilage, necessitating preservation methods to extend its shelf life while retaining its nutritional and sensory qualities. Pasteurization is one of the key techniques employed to achieve this goal.
Pasteurization involves heating the milk to a specific temperature for a defined duration to destroy harmful microorganisms while preserving essential nutrients. However, the process can influence the overall quality of tiger nut milk, including its taste, texture, color, and nutritional content. Various studies have shown that different combinations of pasteurization temperature and time can lead to diverse impacts on the physicochemical properties, sensory attributes, and microbial load of plant-based milk products (Awua, 2019; Okonkwo et al., 2021).
This chapter will address the background information that motivated this study, the challenges that prompted it, its aim, and its objectives as a preface to subsequent sections of the study. Additional factors include the study's significance, scope, limitations, research questions, and the definition of technical terms.
1.2 Background of Study
The cultivation and consumption of tiger nuts can be traced back to ancient Egypt and the Mediterranean region, where these tubers were valued for their nutritional properties. Tiger nut milk, historically known as “horchata de chufa,” has been a staple beverage in Spain for centuries, particularly in the Valencia region. Traditionally made by soaking and grinding tiger nuts, this refreshing drink was initially consumed without any form of preservation, making it highly perishable and susceptible to spoilage (Martínez et al., 2016). As the consumption of tiger nut milk spread globally and gained popularity as a plant-based alternative to dairy milk, especially in recent years, there arose a need for better preservation techniques. This led to the exploration of pasteurization methods, a technique developed by Louis Pasteur in the 19th century. Pasteurization, originally used in the wine and dairy industries, was adapted to preserve non-dairy milk, including tiger nut milk, by inactivating pathogenic microorganisms while maintaining its sensory and nutritional properties (Nwachukwu & Ezeigbo, 2013).
Research into optimizing pasteurization conditions for tiger nut milk began in the early 21st century, driven by the increasing demand for safe, shelf-stable, and high-quality plant-based beverages. Initial studies revealed that different combinations of temperature and time significantly impact the milk's physicochemical properties, including its nutritional content, flavor, color, and texture. Higher temperatures and longer times effectively reduce microbial load but may lead to nutrient degradation and undesirable sensory changes, while lower temperatures may fail to ensure safety (Ade-Omowaye et al., 2009).
Tiger nut (Cyperus esculentus), also known as earth almond or chufa, is a small tuber widely cultivated in various regions, particularly in Africa and the Mediterranean. For centuries, it has been consumed due to its rich nutritional profile, providing dietary fiber, essential fatty acids, vitamins, and minerals. In recent years, tiger nut has gained popularity as a raw material for producing plant-based milk, which serves as a lactose-free alternative to conventional dairy milk. Tiger nut milk is valued for its creamy texture, slightly sweet taste, and numerous health benefits, such as aiding digestion and promoting heart health (Bamishaiye & Bamishaiye, 2011). Despite its benefits, the production and storage of tiger nut milk face challenges, primarily due to microbial contamination and quality degradation. Like most plant-based beverages, tiger nut milk is susceptible to spoilage, necessitating effective preservation techniques to maintain its safety, sensory attributes, and nutritional content. Among various preservation methods, pasteurization remains the most widely used in the food industry. It involves heating the milk to a specific temperature for a predetermined time to inactivate pathogenic microorganisms and reduce spoilage, thereby extending shelf life.
However, pasteurization can significantly affect the quality of the milk, influencing its flavor, texture, nutritional value, and color. The combination of pasteurization temperature and time plays a crucial role in determining these effects. Research indicates that higher temperatures and longer pasteurization times can lead to nutrient loss and undesirable changes in sensory properties, while inadequate pasteurization may fail to ensure microbial safety (Olanipekun et al., 2019; Eze, 2020). Consequently, optimizing pasteurization conditions specific to tiger nut milk is essential to balance microbial safety with the preservation of its quality characteristics.
1.2.1 Tiger Nut and Tiger Nut Milk
Tiger nut (Cyperus esculentus), a perennial plant native to Africa, is widely recognized for its edible tubers, which have been consumed for thousands of years. Despite its name, tiger nut is not a nut but a small tuber that is rich in nutrients such as fiber, healthy fats, vitamins, and minerals. Traditionally, it has been used in various forms, including raw consumption, roasted snacks, and even flour for baking (Belewu & Belewu, 2007). Due to its nutrient density and health benefits, tiger nut has become increasingly popular as an ingredient in producing non-dairy milk, particularly for individuals seeking plant-based alternatives to cow's milk.
Tiger nut milk, also known as “horchata de chufa” in Spain, is a creamy, slightly sweet beverage that offers a high level of dietary fiber, unsaturated fatty acids, and antioxidants. It is also naturally lactose-free, making it suitable for those with lactose intolerance or milk allergies (Ahmed et al., 2018). The milk has been reported to support digestive health, reduce cholesterol levels, and provide a rich source of essential minerals like potassium and magnesium (Agbaje et al., 2019). Despite its appeal, tiger nut milk is prone to rapid spoilage due to microbial growth, which can affect its safety and shelf life. To mitigate this, pasteurization is commonly employed. The pasteurization process involves heating the milk to specific temperatures for set durations to destroy harmful microorganisms and extend the product's shelf life while aiming to retain its nutritional and sensory qualities. However, achieving the optimal balance between microbial safety and the preservation of nutritional content is challenging, as excessive heat can degrade the product's flavor, texture, and nutrient profile (Olanipekun et al., 2019).
1.3 Statement of Problems
Investigation revealed that tiger nut milk product perishable, the beverage is highly prone to microbial spoilage, which significantly limits its shelf life and affects its safety for consumers (Olanipekun et al., 2019). Although, milk has been successfully processed from fresh tiger nut tubers, not much effort has been made in trying to standardize the processing treatment to maximize nutritive values.
Moreover, pasteurization has been known to optimize food products in terms of most nutritional, microbial and sensory profile, however, few minerals and proteins (amino acids) can be lost during the heat treatment, together with heat-induced changed in color and taste that is not acceptable. It is therefore necessary to standardize heat treatment of tiger nut milk.
1.4 Aim and Objectives of Study
The aim of the study is to evaluate the effect of different pasteurization temperature and time on the quality characteristics of tiger nut milk. In achieving this aim, the following specific objectives were laid out as follows:
- To determine the impact of varying pasteurization temperatures on the physicochemical properties of tiger nut milk, such as pH, viscosity, and color.
- To assess how different pasteurization times influence the sensory attributes of tiger nut milk, including taste, aroma, and texture.
- To analyze the effect of pasteurization temperature and time on the nutritional composition of tiger nut milk, particularly focusing on vitamin and mineral retention.
- To evaluate the microbial stability of tiger nut milk at different pasteurization conditions in order to determine the most effective temperature-time combination for extending shelf life.
- To recommend the best pasteurization temperature and time combination that maintains the desirable quality characteristics of tiger nut milk while ensuring product safety.
1.5 Research Questions
The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:
- How do different pasteurization temperatures affect the physicochemical properties of tiger nut milk, such as pH, viscosity, and color?
- What are the effects of varying pasteurization times on the sensory characteristics of tiger nut milk, including taste, aroma, and texture?
- How does pasteurization temperature and time influence the nutritional content of tiger nut milk, specifically the retention of vitamins and minerals?
- What pasteurization conditions provide the best microbial stability in tiger nut milk to extend its shelf life?
- Which pasteurization temperature-time combination optimally balances microbial safety and the preservation of quality characteristics in tiger nut milk?
1.6 Significance of Study
The outcome realized from the research findings will be significant to the following stakeholders:
- This study will provide food producers with valuable insights into the optimal pasteurization conditions for tiger nut milk, helping them enhance product quality, extend shelf life, and reduce spoilage.
- It will offer researchers and academics new data on the relationship between pasteurization temperature, time, and quality characteristics in plant-based beverages, filling gaps in existing literature.
- The findings will benefit consumers by ensuring they receive a safer, more nutritious, and higher-quality tiger nut milk product that meets their expectations in terms of taste and health benefits.
- Regulatory bodies will gain scientifically backed information that can be used to establish industry standards for the processing and preservation of tiger nut milk and similar plant-based products.
- This research will aid investors and entrepreneurs in making informed decisions regarding the production and commercialization of tiger nut milk, contributing to the growth of the plant-based beverage market.
1.7 Scope of Study
The scope of the research is focused on the effect of different pasteurization temperature and time on the quality characteristics of tiger nut milk.
1.8 Limitations of the Study
The research study was limited by insufficient data availability, as there was a lack of comprehensive existing research specifically focused on the effect of different pasteurization conditions on tiger nut milk. Additionally, frequent power failures during the experimental process caused disruptions, leading to delays and inconsistencies in data collection.
Furthermore, financial constraints restricted access to advanced laboratory equipment and resources, limiting the scope of the analysis. Time constraints also posed challenges, as the research was conducted within a limited period, preventing the exploration of a broader range of variables or extended trials for more robust results.
1.9 Definition of Terms
Tiger Nut Milk:
A plant-based beverage made from the tubers of Cyperus esculentus, known for its creamy texture, slightly sweet taste, and nutritional benefits, including dietary fiber, unsaturated fatty acids, and essential minerals (Ahmed et al., 2018).
Pasteurization:
A heat treatment process designed to kill pathogenic microorganisms in liquids, such as milk, to improve safety and extend shelf life. It involves heating the liquid to a specific temperature for a set period (Nwachukwu & Ezeigbo, 2013).
Physicochemical Properties:
It refers to the characteristics of a substance that include both physical and chemical properties, such as pH, viscosity, and color. These properties are essential for assessing the quality and stability of food products (Olanipekun et al., 2019).
Sensory Characteristics:
Attributes of a food product perceived by the senses, including taste, aroma, texture, and appearance. These characteristics are crucial for evaluating consumer acceptability and overall product quality (Eze, 2020).
Nutritional Composition:
It is the profile of nutrients present in a food product, including vitamins, minerals, proteins, fats, and carbohydrates. This composition determines the health benefits and nutritional value of the product (Ade-Omowaye et al., 2009).
