Replacing the animal fat in Bologna sausages using high internal phase emulsion stabilized with lentil protein isolate (Lens culinaris).

High internal phase emulsions (HIPEs) are promising techniques that can replace saturated fat in food without reducing the product's texture, sensory attributes, water-holding capacity, and cooking loss. In the current investigation, 100% pork back fat was replaced by HIPEs formed with lentil protein isolate (LPI) in Bologna sausages. HIPEs were prepared by 25% LPI dispersion (2, 4, 6, and 8%, w/w) and 75% (w/w) soybean oil. HIPEs with higher LPI concentration (4, 6, and 8%, w/w) showed lower droplet size, firmer appearance, and better rheology behavior than 2% LPI. The concentrations LPI (2%, 4%, 6%, and 8%, w/w) led to increased moisture in sausages (FH2, FH4, FH6, and FH8, respectively) compared to the FC. These LPI levels resulted in sausage values for pressed juice similar to the FC and lower energy values than sausages with soybean oil (FO) and pork back fat (FC). Besides, these LPI concentrations (4%, 6%, and 8%, w/w) resulted in a lower oil oxidation level in sausages with HIPEs (FH4, FH6, and FH8, respectively) compared to the control sausage formulation with pork back fat (FC). Bologna sausages elaborated with HIPEs showed emulsion stability values higher than 97%, without significance difference between them. The texture and sensory properties of sausages made with HIPEs were comparable to those made with pork back fat. HIPEs may improve the oxidation stability of the Bologna sausages. These results highlight the effectiveness of HIPEs structured with lentil protein in successfully substituting pork back fat in Bologna sausages with a better nutritional appeal.

Does protein deamidation enhance rice protein concentrate's ability to produce and stabilize high internal phase emulsions?

Rice is one of the most consumed grains in the world. Rice protein has great nutritional value as a hypoallergenic protein and due to its high lysine content, a limiting amino acid in several other plant protein sources. However, rice protein has low solubility, hampering its use in many applications in the food industry. In this context, alkaline deamidation (0.5 h, 343 K, and pH 11) was applied to modify the protein structure of rice protein concentrate (RPC). After deamidation, two protein powders were produced: (i) one containing the whole protein fraction recovered after RPC deamidation (DT) and (ii) another containing only the soluble fraction recovered after RPC deamidation (DS). Protein dispersions were characterized by SDS-PAGE, zeta potential, solubility, surface hydrophobicity, and capacity to hold water and oil. RPC could not structure canola oil into a high internal phase emulsion (HIPE) due to its low solubility. DT and DS dispersions displayed solubility much higher than RPC and enabled the structuration of HIPEs with 75 % (w/w) canola oil and 25 % of DT or DS dispersions (2, 4, and 6 % w/w). HIPEs were characterized regarding particle size, microstructure, Turbiscan and oil loss stabilities, and rheological behavior for 60 days. Turbiscan analysis and oil loss measurements showed high stability, and the thixotropy tests showed high recovery in all HIPEs. Higher protein concentrations and DS dispersions produced HIPEs with smaller particle sizes. However, rheological measurements indicate that HIPEs produced with DT dispersions had better results, maintaining their structure over the 60 days. Furthermore, DT is cheaper to produce; therefore, DT 4 and 6 % w/w were the most promising for producing HIPEs. The HIPEs produced in this study displayed great potential as fat replacers.

Thermo-induced changes in the structure of lentil protein isolate (Lens culinaris) to stabilize high internal phase emulsions.

This study aims to assess the impact of heat treatment on the emulsifying properties of lentil protein isolate (LPI) dispersion to produce high internal phase emulsions (HIPEs). The heat-treated LPI dispersion was characterized by size, turbidity, solubility, zeta potential, free sulfhydryl group, electrophoresis, differential scanning calorimetry, circular dichroism, Fourier transforms infrared spectroscopy and intrinsic fluorescence. HIPEs were produced with 25% of LPI dispersion (2%, w/w) and soybean oil (75%) using a rotor-stator (15,500 rpm/1 min). HIPEs were evaluated for their droplet size, zeta potential, centrifugal stability, microscopy, appearance, Turbiscan stability, and rheology over 60 days (25 °C). Heat treatment reduced the size of LPI, resulting in increased turbidity, solubility, and exposure of hydrophobic groups. HIPEs produced with heat-treated LPI at 70 °C (HIPE70) and 80 °C (HIPE80) for 20 min exhibited lower droplet sizes, increased stability, reduced oil loss, and a homogeneous appearance compared to HIPE produced with untreated LPI (HIPEc). In addition, HIPE70 and HIPE80 displayed resistance to shear stress, higher apparent viscosity, and increased storage modulus than HIPEc. HIPEs produced with heat-treated LPI were stable, suggesting that the treatment was efficient for improving the functional properties of the protein and the possibility of future research focusing on fat substitutes in food applications.