Pumpkin seed proteins (PSPs) are a promising resource for obtaining bioactive peptides but their low solubility hinders enzymatic hydrolysis, reducing yield and bioactivity. In addition, enzymatic processes require specific conditions and long processing times; improving the efficiency of this process is essential to expand its industrial applications. In this context, using a high-frequency, low-intensity ultrasound (US) has proven to be an effective strategy for optimizing the hydrolysis of plant protein. This study evaluated the US-assisted (38 W/L, 40 kHz) and conventional hydrolysis of pumpkin seed proteins (PSPs) for 180 min at 25 °C, 40 °C, and at the optimum temperature condition for each enzyme studied (60 °C for Brauzyn^®, 55 °C for Flavourzyme^®, and 50 °C for Neutrase^®), as well as the impact of this process on the macrostructural and functional characteristics of the hydrolysates obtained. The degree of hydrolysis (DH) was significantly higher in US-assisted reactions, reaching increases of up to 57.7% with Neutrase^® at 40 °C. The US also positively influenced the protein solubility of the hydrolysates, especially at pH levels close to the isoelectric point, with improvements of up to 100%, compared to the hydrolysates obtained from the conventional reaction. The antioxidant activity was also enhanced by the US, compared to the conventional reaction, emphasizing the hydrolysates obtained through the action of Flavourzyme^®, which showed increases of 52.4% and 42.6% in the scavenging of DPPH and ABTS radicals, respectively. The analysis of the mean particle size revealed significant reductions with the US (<26.2%). Consequently, the polydispersity index (PDI) demonstrated greater uniformity in the particles obtained from the US-assisted reactions (reductions of up to 20.3%). UV-Vis spectroscopy and intrinsic fluorescence also indicated possible alterations in the tertiary structure of the peptides obtained, mainly in US-assisted reactions. Therefore, US-assisted PSP hydrolysis resulted in better enzymatic performance and produced protein hydrolysates with bioactive potential for food applications.

This work investigated the fermentation kinetics and characteristics of goat yogurt supplemented with bovine whey protein isolate (WPI) (0%, 2.5% and 5.0%) subjected to high shear dispersion (HSD) assisted by ultrasound (US). Protein supplementation and the physical processes increased the electronegativity of the zeta potential (≤60%), whereas particle size reduction was observed only with physical processes (≤42%). The addition of 2.5% WPI reduced yogurt fermentation time by 30 min. After 24 h of storage at 7 °C, lactic acid bacteria counts did not differ between samples (≥8 log CFU/mL), and the supplementation was sufficient to increase the apparent viscosity (≤5.65 times) and water-holding capacity (WHC) of the yogurt (≤35% increase). However, supplementation combined with physical processes promoted greater improvements in these parameters (6.41 times in apparent viscosity and 48% in WHC) (p < 0.05), as confirmed by the denser and better-organized protein clusters observed in microscopic evaluation. Thus, both approaches proved to be promising alternatives to improve goat yogurt quality. Therefore, the decision to adopt these strategies, either independently or in combination, should consider cost implications, the product quality, and market demand.

As proteínas vegetais são uma boa alternativa às fontes animais na obtenção de hidrolisados com atividades técnico-funcionais devido à sua segurança, baixo custo e facilidade para produção em larga escala. Os hidrolisados proteicos podem potencializar as funcionalidades das proteínas, resultando na melhoria de diversas propriedades técnico-funcionais como a capacidade de retenção de água e óleo, emulsificação, solubilidade, propriedades espumantes e gelificantes. Dentre os principais métodos utilizados para a obtenção de hidrolisados a partir de proteínas vegetais, destaca-se a hidrólise enzimática. Este método apresenta diversas vantagens em relação a hidrólise química, tais como, a alta especificidade e baixa toxicidade. Neste contexto, este trabalho faz uma abordagem sobre os hidrolisados derivados de proteínas vegetais e suas principais propriedades técnico-funcionais estudadas.

Goat milk cheese production is gaining attention due to its nutritional value and potential for niche markets. However, technological challenges, mainly curd fragility and low yield, often limit large-scale processing and quality standardization. Thus, this study investigated the use of ultrasound (US) during milk coagulation as a strategy to enhance curd formation and cheese-making efficiency. The impact of US on recombinant chymosin activity was first assessed, showing that short sonication (5 min at 30 °C) increased proteolytic activity by up to 92% and milk-clotting activity by 22% ( p < 0.05). During coagulation, US reduced rennet coagulation time by up to 10%. Partial US-assisted coagulation (8 and 16 min) increased spontaneous syneresis (from 2 to 7% after 40 min), reduced curd mass loss during drainage (≤ 34%), and enhanced solid retention in the gel (up to 45% reduction in whey solids). These effects resulted in cheeses with higher yield (up to 39.5%) and increased protein (≤ 5%) and fat content (≤ 11%). Compared with the control cheese, those produced with US intervention exhibited higher proteolysis, greater elastic modulus, and improved elasticity after 21 days at 7 °C, without significant changes in pH, acidity, or color. Therefore, partial US-assisted coagulation (8 and 16 min) enhanced recombinant chymosin activity and induced colloidal changes in the milk matrix, contributing to improved coagulation efficiency and technological properties of fresh goat cheese, including higher yield, greater solids retention, and better texture. These findings highlight ultrasound as a promising tool to optimize goat cheese production and improve process efficiency in the dairy industry.