Vegetables, rice and vegetable protein

The growing demand for vegetable proteins, driven by population increase and interest in sustainable protein-rich diets, has generated a focus on the use of legumes and cereals as protein sources for the production of meat analogues due to their complementary nutritional profile and lower environmental impact. However, the analogues should not only imitate the nutritional profile of meat, but their texture is also important for good commercialization. One of the processes used to improve these properties is protein texturization by thermoextrusion, which could modify the availability and digestibility of amino acids. Thus, the objective of this work is to evaluate the in vitro bioaccessibility of proteins and amino acids from pea and rice protein isolates (I) and texturized proteins (T). Proteins from pea (PP), rice (RP) and a 50 : 50 mixture (PRP) were processed by extrusion, evaluating the effects on digestibility and bioaccessibility of essential (EAA) and non-essential (NEAA) amino acids. The results showed higher in vitro digestibility and bioaccessibility of NEAA of texturized proteins compared to isolated proteins, although this effect is not significant for PP. However, texturization significantly reduced the bioaccessibility of some EAA such as lysine. Rice protein showed greater stability during the extrusion process, maintaining a more balanced amino acid profile. Texturization can therefore be a useful tool to improve the functionality of vegetable proteins, but it is necessary to optimize the process to minimize nutritional losses.

Most gluten-free products have lower protein content than their counterparts with wheat flour. The addition of exogenous proteins could not only be a good option to compensate for this reduction but also a tool to create gluten-free products rich in protein. However, the different water-binding capacities of proteins modify dough rheology, which also affects bread volume. Therefore, this study aimed to analyse the incorporation of a high percentage (30%) of several proteins (rice, pea, egg white and whey protein) in gluten-free breads whose hydration levels were adjusted for each protein to achieve the maximum volume. In this way, the breads with vegetal proteins required a higher amount of water than the breads with animal proteins. Moreover, all enriched breads exhibited lower maximum volume values than control, and the ones with whey protein presented the lowest volumes overall. From these results, the rheological behaviour and characteristics (colour, texture and weight loss) of optimised doughs and breads were measured. The doughs with whey protein presented the highest G′ and G″ values due to their low hydration level, and the ones with egg white protein were very watery. Regarding colour, the addition of protein led to darker crusts, with the ones with whey protein being the darkest. With respect to the control, breads with animal proteins exhibited higher hardness, especially with whey protein, while the ones with vegetal proteins did not present significant differences.

(1) Foods with attractive shapes have been receiving increasing interest from researchers, particularly for foods for children. The ability to particularize foods by imparting attractive aspects to nutritious and less attractive food ingredients, such as vegetables or proteins, is an interesting challenge for the food industry. In this context, the rheological characteristics of food doughs are fundamental for obtaining form-forming foods that are able to maintain a shape of their own. (2) Broccoli, pumpkin, carrot and zucchini wastes (stems, leaves, and off-gauge veggies), which are still rich in nutrients, from the food industry were used in this work to enrich burgers with vegetable proteins. The doughs were characterized by rheological analysis using a frequency sweep test and a temperature ramp test. They were also shaped with attractive molds and baked. (3) From the frequency sweep test, the formulation with brown rice proteins resulted in better consistency; all samples showed a solid-like behavior. (4) Workable doughs were formulated using vegetal wastes from the food industry. Among the proteins used, those from brown rice were found to be the most suitable for the preparation of a vegetable burger.

The rising demand for plant-based proteins has highlighted textured vegetable proteins (TVPs), which are mainly produced via extrusion. Rice bran, a low-cost byproduct of rice processing with up to 20% protein, is a promising source for protein extraction. While studies have explored rice protein, research on moisture content in extrusion to enhance TVP properties for plant-based products is limited. This study examined the effects of increasing rice protein concentrate (RPC) and moisture content on TVPs produced through low-moisture thermoplastic extrusion for burger applications, using a 22 central composite rotatable design (CCRD). The findings highlighted the importance of balancing soy and rice proteins, along with moisture, optimizing TVPs with suitable properties for hamburger analogs. Optimal conditions for producing TVPs for hamburger analogs in our study involved replacing 10–20% of soy protein isolate (SPI) with rice protein concentrate (RPC) and using a total moisture content of 20–25% in the mixture.

Interfacial behavior of vegetable protein isolates at sunflower oil/water interface