Cricket protein-saccharide conjugate as a novel functional ingredient and application in cheese

Abstract

This research aims to improve cricket protein characteristics by conjugation with saccharides via the Maillard reaction (MR) for utilization as an alternative protein and bioactive compound carrier in functional food. The effect of different saccharides (Inulin and fructooligosaccharides; FOS) and Maillard condition at 70 ℃ (pH = 8-10, thermal treatment duration = 6-24 h) with cricket protein conjugation on structural, functional properties and antioxidant activities was studied. The results demonstrated that the difference in pH and thermal treatment duration with inulin and FOS through MR significantly enhanced the browning intensity, color development, and degree of glycation of cricket protein (p < 0.05). Moreover, the conjugated cricket protein showed superior water solubility, oil-holding capacity, emulsifying properties, and antioxidant properties compared to the unconjugated product. However, the excessive condition of MR (treatment time > 6 h, pH > 9) had a detrimental effect on the functional properties and over-browning color of the conjugated products. Therefore, the conjugation of cricket protein with FOS at pH 9 through MR was selected for further study by novel technology for solving the process of time-consuming and over-browning of the final product. The new technology of ultrasound (UL = 2-58 min) and microbubbles (MB = 6-35 min) assisted the MR process using the response surface methodology (RSM) was investigated. The optimized conditions of MR assisted by UL and MB were 26.27 min of UL and 18.06 min of MB, resulted in the most favorable functional properties (WS = 89.38 g/L, OHC = 8.65%, EAI = 81.37 m2/g, and ESI = 120.75 min) and the highest antioxidant activity (DPPH = 14.77, ABTS = 14.55 and FRAP = 13.98 µmol TE/g). Furthermore, it was observed that the browning index of cricket protein-FOS conjugated product (CPF) had no significant impact on the UL and MB (p > 0.05). The effect of conjugated cricket protein powder on the physicochemical and stability of oil-in-water emulsions incorporating vitamin D3 and their cytotoxicity was investigated. The oil-in-water (O/W) emulsions with vitamin D3 were stabilized by cricket protein powder (CP), cricket protein-FOS mixture (CPM), and CPF with 0.3%, 0.5%, and 1.0% (w/v) concentrations. CPF was used to stabilize the vitamin D3-emulsion resulting in di-modal distributions, and larger mean particle size diameters but more stable and uniform particle sizes compared to CP and CPM. The CPF was found to improve the storage stability of emulsions and vitamin D3 release (4 ℃, 0-30 days). The CPF-stabilized vitamin D3 emulsions exhibited enhanced vitamin D3 bioaccessibility (37-54%), surpassing that of CP (27-34%) and CPM (32-37%). In addition, CPF exhibited superior vitamin D3 stability during in vitro gastrointestinal digestion. Moreover, the effectiveness of CPF, particularly at a 1% (w/v) concentration, in increasing the vitamin D3 bioaccessibility, and the storage stability of emulsions was better than 0.3 and 0.5% (w/v) concentrations. The concentration required for 50% inhibition of cell viability of CP, CPM, CPF, and CPF-vitamin D3 emulsion was high, indicating low cytotoxic activity. The application of conjugated cricket protein powder into imitation cheese products was also investigated. The effect of CPF as a partial replacement for rennet casein at varying levels (10-40 g/100g) on the physicochemical and functional properties, vitamin D3 stability, and sensorial attributes of imitation mozzarella cheese was studied. Utilizing CPF as a partial substitute for rennet casein in imitation mozzarella cheese can heighten antioxidant properties and enhance vitamin D3 stability of the cheese by approximately 3 times after heat treatment and 2.8 times after 28 days of storage at 4 °C in comparison to the control. Furthermore, the physical, textural, and sensory properties of the cheese were maintained similarly to the control cheese. The inclusion of 10-20 g/100g of CPF in imitation cheese can enhance vitamin D3 stability and can be accepted by consumers.