Minimising variation in aspalathin content of aqueous green rooibos extract: optimising extraction and identifying critical material attributes.

• Autores: Neil Miller, Dalene De Beer, Elizabeth Joubert
• Localización: Journal of the science of food and agriculture, ISSN 0022-5142, Vol. 97, Nº 14, 2017, págs. 4937-4942
• Idioma: inglés
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• Resumen

  • High levels of aspalathin, an antidiabetic dihydrochalcone, in green rooibos underpins interest in the production of a standardised extract. Elements of a quality-by-design approach were applied to optimise extraction conditions, aiming at the delivery of a dry matter yield (DMY) ≥ 160 g kg-1 and an extract with an aspalathin content (AC) ≥ 80 g kg-1 .; Results: Hot water extraction parameters, namely extraction time, extraction temperature and water-to-plant material ratio, were optimised for DMY and aspalathin extraction efficiency (AEE) using Design of Experiments. Good polynomial prediction models were obtained and multiresponse desirability plots indicated 37 min, 93 °C and 23:1 as optimal conditions. Even when using 30 min and 10:1 instead for practical reasons, the target DMY and AC values could be achieved with the caveat that plant material with an AC ≥ 30 g kg-1 is used. Particle size distribution and stem content were identified as contributing to variation in the AC of raw material.; Conclusion: By setting raw material specifications in terms of AC, as well as applying practical optimum extraction conditions, 160 g kg-1 extract with an AC ≥ 80 g kg-1 could be consistently achieved from green rooibos plant material. © 2017 Society of Chemical Industry.; © 2017 Society of Chemical Industry.