Abstract A Box-Behnken design was employed to optimize ultrasound-assisted enzymatic extraction of polysaccharides from perilla leaves. Four independent variables, namely, liquid-to-solid ratio, enzymatic time, enzymatic temperature, and ultrasonic power were investigated. Under the optimal liquid-to-solid ratio of 41:1, enzymatic time of 40 min, enzymatic temperature of 49 °C, and ultrasonic power of 204 W, the experimental polysaccharide yield was 3.84% (n = 3), which was close to the value predicted by response surface methodology (3.9%). Four polysaccharides (PLP1, PLP2, PLP3, and PLP4) were obtained with DEAE-cellulose-52 and Sephadex G-100 chromatography, and their antioxidant activities were investigated with various antioxidant assays in vitro. All the four polysaccharides possessed good antioxidant properties in a concentration-dependent manner, and PLP3 presented the highest antioxidant activity. Thus, the novel polysaccharides extracted from perilla leaves could be promising bioactive macromolecules that can be applied as potential antioxidants in medical and food industries.

Abstract Response surface methodology (RSM) was used to optimize the ultrasound-assisted extraction parameters of perilla protein isolate (PPI), which has functional properties. A central composite experimental design was applied to investigate the effects of three factors (ultrasonic power, extraction time, and liquid-to-solid ratio) on six responses: protein yield, water solubility index (WSI), water absorption capacity (WAC), oil holding capacity (OHC), emulsifying activity (EA), and foaming ability (FA). Based on the RSM results, the optimum conditions were an ultrasonic power of 206 W, and extraction time of 32.4 min, and a liquid-to-solid ratio of 10.34:1. Under these conditions, PPI had high protein yield (26.1%) and functional properties (55.2% WSI, 3.6% WAC, 1.76 g/g OHC, 60.25 m2/g EA, 63.2% FA). Differential scanning calorimetry revealed that PPI was slightly denatured at 75.16 °C, and the amount of heat required to induce this denaturation was 0.03 J/g. SDS-PAGE presented protein bands that ranged from 14.4 to 66.2 kDa. Based on its functional properties, PPI can be used in the food industry.

Abstract Response surface methodology (RSM) was used to optimize ultrasound-assisted aqueous enzymatic extraction (UAAEE) conditions for perilla seed oil. Under the optimum conditions—which were a liquid-to-solid ratio of 4.4:1, a hydrolysis time of 2.66 h, a hydrolysis temperature of 50.87 °C and an ultrasound treatment time of 24.74 min—an oil yield of 31.34% was obtained. Comparisons of the physicochemical characteristics of oil obtained using UAAEE with those of oil obtained by solvent extraction (SE oil) and cold pressing extraction (CPE oil) revealed similar refractive indices and saponification values, but UAAEE oil had a higher iodine value and better stability against oxidation, with a low peroxide value. UAAEE oil contained higher levels of beneficial α-linolenic acid and phenolics than SE oil or CPE oil, and it also had superior efficiency in scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals.

Um masterbatch (MA) reativo de poliamida 6 (PA6)/SiO2 contendo 20% (fração de massa) de nano-SiO2 foi preparado. Posteriormente, o MA reativo preparado foi usado como carga no preparo de nanocompósitos PA6/SiO2 (RA). A estrutura do RA foi analisada por espectrometria no infravermelho por transformada de Fourier (FTIR), microscopia eletrônica de transmissão (TEM), difratometria de raios X (XRD), microscopia eletrônica de varredura (SEM) e microscopia óptica de luz polarizada (POM). A estabilidade térmica e o comportamento de cristalização do RA foram avaliados por análise termogravimétrica (TGA) e calorimetria exploratória diferencial (DSC). OS resultados indicaram que as cadeias moleculares de PA6 estavam ancoradas na superfície do nano-SiO2 através de ligações químicas entre a superfície de grupos amino do nano-SiO2 e do monômero da ε-caprolactama ou pré-polímero da PA6. Como resultado, uma camada interfacial flexível foi formada, melhorando a compatibilidade do nano-SiO2 com a matriz de PA6. Além disso, o efeito no nano-SiO2 apresentou melhoras nas propriedades mecânicas do RA. Devido ao efeito de impedimento de movimento das cadeias moleculares da PA6 pelas partículas de nano-SiO2, o tamanho da esfera cristalina de PA6 foi menor e sua forma cristalina também foi afetada. A massa molar da matriz de PA6 tende a decair gradualmente com o aumento do conteúdo nano-SiO2.

A reactive polyamide 6 (PA6)/SiO2 masterbatch (MA) containing 20% (mass fraction) of nano-SiO2 was prepared readily. Furthermore, the as-prepared reactive MA was used as a filler to prepare PA6/SiO2 nanocomposites (RA). The structure of RA was analyzed by means of Fourier transform infrared spectrophotometry (FTIR), transmission electron microscopy (TEM), powder X-ray diffractometry (XRD), scanning electronic microscopy (SEM) and polarizing microscopy (POM). Thermal stability and crystallization behaviors of RA were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Findings indicated that the PA6 molecular chains were anchored on the surface of nano-SiO2 through chemical bonding between the surface amino groups of nano-SiO2 and ε-caprolactam monomer or prepolymer of PA6. As a result, a flexible interfacial layer was formed, thereby improving the compatibility of nano-SiO2 with PA6 matrix. Moreover, the enhancement effect of nano-SiO2 led to the improved mechanical properties of RA. Besides, due to the hindering effect of nano-SiO2 particles to the movement of PA6 molecular chains, the size of the PA6 spherocrystal was smaller, and its crystalline form was also affected. Furthermore, the molecular weight of the PA6 matrix tended to decrease gradually with increasing nano-SiO2 content.