The Effect of High-Pressure Microfluidization Treatment on the Foaming Properties of Pea Albumin Aggregates.

The effect of dynamic high-pressure treatment, also named microfluidization, on the surface properties of thermal pea albumin aggregates (AA) and their foaming ability was investigated at pH 3, 5, and 7. The solubility of albumin particles was not affected by the increase in microfluidization pressure from 70 to 130 MPa. Particle charge depended only on the pH, whereas protein surface hydrophobicity was stable at pH 5, decreased at pH 3, but increased at pH 7 after microfluidization treatment and with the applied pressure. Surface tension of AA measured at air/water interface was favorably affected by the microfluidization treatment at each pH preferentially due to size reduction and increased flexibility of protein particles. The foaming capacity and stability of AA depended on the pH conditions and the microfluidization treatment. The high-pressure treatment had little influence in foaming properties at acidic pHs, probably related to a more compact form of AA at these pHs. At neutral pH, the foaming properties of pea AA were strongly influenced by their surface properties and size associated with significant modifications in AA structure with microfluidization. Changes in albumin aggregate characteristics with pH and microfluidization pressure are also expected to modulate other techno-functional properties, such as emulsifying property. PRACTICAL APPLICATION: Albumins are known for their interesting nutritional values because they are rich in essential amino acids. This fraction is not currently marketed as a protein isolate for human consumption, but can be considered as a potential new vegetable protein ingredient. This document demonstrated that heat treatment or dynamic high-pressure technology can control the foaming properties of this protein for possible use in expanded foods.

Drying method determines the structure and the solubility of microfluidized pea globulin aggregates.

The effects of microfluidization and drying method on the characteristics and techno-functional properties of pea (Pisum sativum L.) globulin aggregates were investigated. Pea globulin aggregates were microfluidized at 130 MPa and spray-dried or freeze-dried thereafter. Microfluidization decreased aggregate size and surface hydrophobicity due to protein re-arrangements. Microfluidized pea globulin aggregates showed higher solubility but less suspension stability than non-microfluidized aggregates. Drying favored the re-aggregation of pea globulins with modifications in secondary structure of proteins more marked for spray-drying, decreased surface hydrophobicity and solubility, but increased suspension stability. Spray-dried aggregates were smaller than freeze-dried, with improved suspension stability. These results indicated that microfluidization and drying determine the structure of pea globulin aggregates and their associated techno-functional properties. These findings are crucial for the preparation of plant protein powders in the food industry.

The foaming properties of camel and bovine whey: The impact of pH and heat treatment.

The effect of heat treatment (70°C or 90°C for 30min) on the foaming and interfacial properties of acid and sweet whey obtained from bovine and camel fresh milk was examined. The maximum foamability and foam stability were observed for acid whey when compared to sweet whey for both milks, with higher values for the camel whey. This behavior for acid whey was explained by the proximity of the pI of whey protein (4.9-5.2), where proteins were found to carry the lowest negative charge as confirmed by the zeta potential measurements. Interfacial properties of acid camel whey and acid bovine whey were preserved at air water interface even after a heat treatment at 90°C. These results confirmed the pronounced foaming and interfacial properties of acid camel whey, even if acid and sweet bovine whey exhibited the highest viscoelastic modulus after heating.