Comparative study on the effect of radio frequency and high-pressure pasteurization on the texture, water distribution, and rheological properties of Nostoc sphaeroides
- 223 Downloads
Nostoc sphaeroides has been used as herbal medicine and dietary supplement in Asian countries from prehistoric times. When N. sphaeroides is pasteurized using conventional high-pressure (HP) steam (121 °C, 30 min), its natural texture and nutritional ingredients are negatively affected. This study investigated the effect of radio frequency (RF) heating on the degree of microbial kill, texture, water distribution, and rheological properties of N. sphaeroides and compared the effect of HP steam (121 °C, 30 min) pasteurization on these parameters. RF (6 kW, 27 MHz) pasteurization was carried out for 10, 20, and 30 min at 67 °C. The results showed that the RF heating carried out for 20 min achieved a 3 log reduction of bacteria which met the safety standard. The effects of RF pasteurization on the texture, water distribution, and rheological properties of N. sphaeroides were significantly lower than that in HP steam pasteurization. Therefore, the application of RF heating in N. sphaeroides would help broaden its application in food, health, and pharmaceutical formulations.
KeywordsNostoc sphaeroides Cyanobacteria RF heating Texture Water distribution Rheological properties
We acknowledge the financial support from National Key R&D Program of China (Contract No. 2017YFD0400501), National Natural Science Foundation Program of China (Contract No. 31671864), Jiangsu Province (China) “Collaborative Innovation Center for Food Safety and Quality Control” Industry Development Program, and Jiangsu Province (China) Infrastructure Project (Contract No. BM2014051), all of which enabled us to carry out this study.
- Brüll LP, Huang Z, Thomas-Oates JE, Paulsen BS, Cohen EH, Michaelsen TE (2000) Studies of polysaccharides from three edible species of Nostoc (cyanobacteria) with different colony morphologies: structural characterization and effect on the complement system of polysaccharides from Nostoc commune. J Phycol 36:871–881CrossRefGoogle Scholar
- Guan D, Cheng M, Wang Y, Tang J (2004) Dielectric properties of mashed potatoes relevant to microwave and radio-frequency pasteurization and sterilization processes. J Food Sci 69:30–37Google Scholar
- Monzon ME, Biasi B, Mitcham EJ, Wang S, Tang J, Hallman GJ (2007) Effect of radio frequency heating on the quality of “Fuyu” persimmon fruit as a treatment for control of the Mexican fruit fly. Hortscience 42:125–129Google Scholar
- Park YK, Rasmussen HE, Ehlers SJ, Blobaum KR, Lu F, Schlegal VL, Carr TP, Lee JY (2008) Repression of proinflammatory gene expression by lipid extract of Nostoc commune var sphaeroides Kützing, a blue-green alga, via inhibition of nuclear factor-κB in RAW 264.7 macrophages. Nutr Res 28:83–91CrossRefPubMedGoogle Scholar
- Plaza-Gonzalez P, Monzo-Cabrera J, Catala-Civera JM, Sanchez-Hernandez D (2005) Effect of mode-stirrer configurations on dielectric heating performance in multimode microwave applicators. IEEE Trans Microwave. Theory 53:1699–1706Google Scholar