ABSTRACT
ABSTRACT: Rice bran is a by-product of the rice milling process, found worldwide in abundance and highlighted due its protein content. This study optimized the conditions for ultrasonic-assisted extraction of protein from defatted rice bran (DRB) and characterized the rice bran protein concentrate (RBPC). A sequential strategy of experimental design was employed; the effect of pH, temperature, ultrasound exposure time, and amplitude were evaluated regarding the percentage of protein extraction by a Full factorial design (FFD) with a fixed frequencies (FFD-A: 37 kHz; FFD-B: 80 kHz). Subsequently, the percentage of protein extracted was optimized employing a Central composite rotatable design (variables: pH and ultrasound exposure time) and RBPC obtained was characterized regarding chemical and functional properties. The pH and ultrasound exposure time had positive effect (P ≤ 0.05) on percentage of protein extraction; moreover, 37 kHz frequency was more effective in protein extraction. The optimized condition (frequency: 37 kHz; temperature: 30 °C; pH: 10; ultrasound exposure time: 30 min; and amplitude: 100%) allowed 15.07% of protein recovery and the RBPC presented 84.76 g 100 g-1 of protein. Magnesium and copper were the main mineral in RBPC (34.4 and 25.5 µg g-1, respectively), while leucine was the limiting amino acid (0.42) and threonine presented the highest chemical score (1.0). The RBPC solubility was minimal at pH 4 and higher at pHs 6-10; the water and oil absorption capacity were higher than bovine serum albumin (BSA) and the emulsifying capacity was comparable to BSA, with a suitable stability. It was possible to obtain a higher purity RBPC than described in the literature, due to the optimization in the extraction process steps, with functional properties suitable for application in food products, especially emulsified ones.
RESUMO: O farelo de arroz é um subproduto do processo de moagem do arroz, encontrado em abundância em todo o mundo e destacado devido ao seu teor de proteínas. Este estudo otimizou as condições para a extração assistida por ultrassom da proteína do farelo de arroz desengordurado (DRB) e caracterizou o concentrado de proteína do farelo de arroz (RBPC). Uma estratégia sequencial de desenho experimental foi empregada; o efeito do pH, temperatura, tempo de exposição ao ultrassom e amplitude foram avaliados em relação à porcentagem de extração proteica por um Delineamento Fatorial Completo (FFD) com frequências fixas (FFD -A: 37 kHz; FFD-B: 80 kHz). Posteriormente, a porcentagem de proteína extraída foi otimizada empregando um Planejamento Composto Central (variáveis: pH e tempo de exposição ao ultrassom) e o RBPC obtido foi caracterizado quanto às propriedades químicas e funcionais. O pH e o tempo de exposição ao ultrassom tiveram efeito positivo (P ≤ 0,05) na porcentagem de extração proteica. Além disso, a frequência de 37 kHz foi mais eficaz na extração de proteínas. A condição otimizada (frequência: 37 kHz; temperatura: 30 °C; pH: 10; tempo de exposição ao ultrassom: 30 min; e amplitude: 100%) permitiu 15,07% de recuperação de proteínas e o RBPC apresentou 84,76 g 100 g-1 de proteína. Magnésio e cobre foram os principais minerais da RBPC (34,4 e 25,5 µg g-1, respectivamente), enquanto a leucina foi o aminoácido limitante (0,42) e a treonina apresentou o maior escore químico (1,0). A solubilidade do RBPC foi mínima em pH 4 e superior em pH 6-10; a capacidade de absorção de água e óleo foi maior que a albumina sérica bovina (BSA) e a capacidade de emulsificação foi comparável à BSA, com uma estabilidade adequada. Assim, foi possível obter um RBPC com elevada pureza, maior do que o descrito na literatura, devido à otimização nas etapas do processo de extração, com propriedades funcionais adequadas para aplicação em produtos alimentícios, principalmente emulsificados.
ABSTRACT
Pulses are one of the cheapest sources for the extraction of protein concentrates which can be gainfully utilized for meeting protein needs of specific groups. Techniques for maximum extraction of Pulse protein concentrates were developed for red gram and Bengal gram by standardisation of process parameters involving alkaline extraction followed by isoelectric precipitation. Extraction conditions viz., flour: water ratio – 1:10, pH 9 and stirring time- 4 hours were employed for isolation of the pulse protein concentrates. The protein concentrates extracted from red gram and chickpea were incorporated in ice cream formulations at concentrations of 5 and 10%. The pulse protein concentrate incorporated ice cream at 5% level had a higher sensory score of 8.7 and 8.8 on the nine-point hedonic scale compared to ice cream enriched with 10% pulse protein concentrate (8.4 and 8.5/9.0). The pulse protein enriched ice cream had a high protein content of 11.76 g/100 g compared to 4.90 g/100 g in control. Pulse protein concentrates have a wide food application in designing speciality foods for different age groups and disease conditions. The PPC incorporated protein enriched ice cream would provide for nutritious ice cream having desirable sensory properties with commercialisation prospects.
ABSTRACT
Objective To extract, separate, and purify polysaccharide from Ganoderma lucidum with alkali from the residue after water extraction, characterize the basic physicochemical properties and structural features in detail, and study the immunomodulatory activity in vitro. Methods The polysaccharide LZJ-015 was isolated and purified from the dry fruiting bodies of G. lucidum by alkaline extraction and ethanol precipitation following Q-Sepharose Fast Flow ion exchange chromatography column. Monosaccharide composition and molecular weight of LZJ-0.15 was analyzed by high performance liquid chromatography (HPLC) with PMP precolumn derivatization and high performance gel permeation chromatography-multiple angle laser (HPGPC-MALLS), respectively. The detailed structure of polysaccharide LZJ-0.15 was characterized by 1H-NMR, 13C-NMR, 1H-1H COSY, and 1H-13C HSQC spectrum. The immunomodulatory activity of G. lucidum polysaccharide was test by RAW264.7 cells phagocytose neutral red experiment. Results The molecular weight, molecular radius, and Mw/Mn of LZJ-0.15 were determined to be 24 700, 46.6 nm, and 1.019, respectively. The monosaccharide composition was confirmed to be mainly composed of glucose (92.3%). LZJ-0.15 was →3) Glc (β1→and→6) Glc (β1→linked glucan indicated by NMR spectrum. Moreover, G. lucidum polysaccharide exhibited good immunomodulatory activity in our study. Conclusion G. lucidum polysaccharide LZJ-0.15 from alkaline extraction showed better immune activity than the polysaccharide extracted from water, which would be potentially developed as an effective immunomodulatory agent.