Effect of High-Pressure Homogenization and Heat Treatment on the Emulsification Properties of Oat Protein Concentrate

Abstract

This master thesis project was performed in collaboration with an agricultural cooperative Lantmännen Oats AB, who has developed a dry protein powder concentrate PrOatein™. The powder consists of oat proteins, dextrins, lipids and β-glucans. The aim of the thesis was to investigate the powder’s functionality in a liquid emulsion and see if it can be improved by pre-treating it with thermal heating and high-pressure homogenization (HPH) under different pH conditions. The emulsification properties of the protein concentrate were first evaluated in the means of the protein’s solubility and its efficacy of producing small oil droplets in different pre-treatment conditions. The effect of high-pressure treatment nor heating in slightly alkaline conditions (pH 7.5) was statistically proved. However, the solubility was highest, when the sample was heated to 85 ºC and high-pressured with 600 bars. In slightly acidic conditions (pH 4.5) the effect of high-pressure treatment was significantly proved. Under acidic conditions, the increased temperature during heat treatment and increased pressure during homogenisation decreased the solubility.
The light scattering analysis showed that the particle size in pH 7.5 was smaller at all pre-treatment conditions compared to pH 4.5 The smallest particle size was achieved by treating the sample with pH 7.5 with 85 ºC and 800 bars. The effect of HPH and heat treatment on particle size was also significantly proved.
The stability analysis showed that heat and high-pressure treatment can delay the sedimentation, which is the dominating instability mechanisms in emulsions consisting of 5 % w/v PrOatein™ powder and 3 % v/v oil. The emulsion sedimented, when the oil content was increased to 10 %, suggesting that the optimal ratio of oil and PrOatein™ in a liquid emulsion should be 1:1.

Popular Abstract

Plant-based proteins have an important role to play in our diet. Protein deficiency can trigger loss of muscle mass, which increases the risk of injuries. Moreover, it can increase our appetite and consequently increase the calory intake. However, the food developers face challenges when using plant-based proteins in liquid food products due to their more complex nature compared to animal-origin proteins. But what are those challenges of plant-protein and how to overcome them?
To answer this question let’s take a deeper look on oat proteins. Oats are fascinating grains that have an interesting nutritional profile. Why so? Maybe you have heard of oat β-glucans and their positive effect on health as they can lower the cholesterol level and decrease the risk of cardiovascular disease. That’s not the only health benefit that oats can provide. They are also rich in oat oil, that has high concentration of polyunsaturated fatty acids. And most importantly, oats are source of protein, that could alleviate the health problems mentioned before. Oats are also one of the few plants that thrive here in the rather cold North, making them a good source of local plant-proteins.
Now as we know the importance of proteins and Nordic oats, we can talk about the challenges of oat proteins for the food industry. You probably have not noticed too many protein shakes or protein rich cooking creams with oat protein in the market. One reason for this is the low solubility of oat proteins. Low solubility of proteins in such products results in two unpleasant phenomena. One being the development of sediment layer in the bottom and the other one, the separation of oil in such products. Scientifically speaking, the products including oil and water are called ‘emulsions’. The addition of fat in liquid emulsions (as cooking creams, protein shakes, milk alternatives are) is desired for improved mouthfeel. For example, the fat makes the milkshake nice and silky and less ‘watery’.
The possibilities to increase the use of oat protein powder developed by Lantmännen Oat AB under a trademark PrOatein, that incorporates oat protein, oil, β-glucans and dextrins, is investigated in this thesis project. The thesis explores the potential of heating and high-pressure homogenization to overcome the limitations of using this nutritious and protein rich powder in liquid food systems such as emulsions.

• author: Kägu, Annette
• supervisor: Björn Bergenståhl
• organization: Food Technology and Nutrition (M.Sc.)
• course: KLGM01 20221
• year: 2022
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: oat proteins, high-pressure homogenisation, emulsions, food technology
• language: English
• id: 9090056
• date added to LUP: 2022-06-20 11:20:31
• date last changed: 2022-06-20 11:20:31