Development and characterisation of plant-based (faba bean) yoghurt : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Food Technology, Massey University, Palmerston North, New Zealand
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2024
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Massey University
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Abstract
Increasing awareness of health, environmental, and ethical issues has recently increased the demand for plant-based alternatives to traditional dairy products. Plant-based milk might be a suitable choice for people looking for a healthier option because it often contains less fat, particularly saturated fat, and allergens. In recent years, the faba bean has gradually become popular as a plant protein due to its nutritional and health benefits to consumers. This master's thesis investigates the possibility of producing yoghurt using faba bean milk analogue (FBM), faba bean protein isolates (FPI) and faba bean-dairy hybrid as alternatives to traditional dairy yoghurt. Also, the effects of varying ratios of dairy and faba bean proteins on the texture, rheology, microstructure, nutritional makeup, protein digestibility, and sensory characteristics of yoghurt were investigated. This study aimed to optimize the formulation of faba bean yoghurt to develop a sustainable and nutrient-rich plant-based alternative to dairy yoghurt through a series of analytical procedures. The study's objectives include examining the interactions between faba bean milk analogue, faba bean protein isolates, and dairy milk (DM) in yoghurt production using five different formulations. These formulations include 50% dairy + 50% faba bean milk analogue (SM#2), 50% dairy + 50% faba bean protein isolates, 50% faba bean milk analogue + 50% faba bean protein isolates (SM#3), 100% faba bean milk analogue (SM#4), 50% faba bean milk analogue + 50% faba bean protein isolates (SM#5) and 100% faba bean protein isolates (SM#6). Further, assessing how these interactions affect the final product's texture, rheology, microstructure, and digestibility. The nutritional composition of various faba bean yoghurt formulations was analyzed, focusing on protein, fat, total solids, fibre, and starch content, and compared with traditional dairy yoghurt. The sensory survey was done using an internal untrained panel to evaluate the consumer preferences for different formulations based on attributes such as taste, aroma, texture, colour, and overall acceptability. Additionally, it investigated the influence of varying ratios of FBM, FPI and DM on the rate and extent of protein digestion using a static digestion (INFOGEST) model. Results indicated that yoghurts made with FPI exhibited higher storage (G’) and loss modulus (G”) values, indicating a stronger gel structure compared to those made with DM alone (reference). The product made with DM and FPI (SM#3) showed the lowest G’ and G”. Similar behaviour was observed for apparent viscosity as well. The product made with DM and FBM (SM#2), showed comparatively similar rheological properties. All yoghurt samples' loss tangent (tan δ) values were consistently less than one, indicating a mostly solid character. Texture profile analysis results of the samples showed a significant difference in textural properties like hardness, cohesiveness, springiness, gumminess, and adhesiveness between samples (p<0.05). SM#2 and SM#5 showed the least deviation from the reference (100% dairy yoghurt). Faba bean yoghurt also demonstrated better water-holding capacity and lower syneresis, particularly in formulations with higher FPI (50% and 100%) content (SM#5 & SM#6). Sensory evaluations showed that consumers preferred the formulations that closely matched the texture and flavour of traditional dairy yoghurt. The hybrid formulations of DM and FBM (SM#2) showed the least deviation from the reference (100% DM). In-vitro gastrointestinal digestion was conducted following the INFOGEST method to assess the protein digestibility of the yoghurt samples. Protein hydrolysis expressed as free amino N of all yoghurt samples by pepsin during the gastric phase (0 to 120 min) was relatively lower than in the small intestinal phase. However, all samples including 100% dairy reference showed a significant increase (p<0.05) in the release of free amino N upon the addition of pancreatin and bile salt during the simulated small intestine phase (130-240 min) compared to the gastric phase. The free amino N release (%) was significantly lower (p<0.05) in 100% plant-based yoghurts (SM#4, SM#5 & SM#6) compared to dairy and plant-based hybrid samples (SM#2 & SM#3). In conclusion, the findings suggested that faba bean yoghurt, particularly when blended with DM, can potentially meet consumer preferences and textural properties while providing a nutritious and sustainable alternative to dairy yoghurt. In addition, there is a high potential of producing 100% vegan yoghurt from faba bean proteins, but further studies on improving textural and sensory properties are needed. The study contributes to exploring the options available in the plant-based food market, addressing both environmental and nutritional needs.
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Figures 2.1-2.3 are reused with permission.