RESUMEN
Mandarin peel is a good source of phenolic compounds, which can be extracted by the ultrasound-assisted extraction (UAE) method. This research was to optimize the UAE conditions for maximum mandarin peel extract (MPE) relating to the extract yield, total phenolic content and the content of a mandarin peel rich flavonoid, hesperidin, using a response surface method comparing with the maceration extraction (MAE) method. The results showed that the selected factors (temperature, time and power) have a significant influence on the extraction yield, total phenolic content and hesperidin content. The extraction at 48°C and 56.71W for 40min was considered the optimal UAE condition since it provided the maximum yield (26.52%), total phenolic (15,263.32mgEq gallic/100g DW) and hesperidin (6435.53mg/100g DW). At the same extraction temperature and time, UAE showed greater extraction efficiency than MAE with 1.77 times higher yield than that of MAE.
Asunto(s)
Citrus , Fenoles/análisis , Flavonoides , Hesperidina , Extractos VegetalesRESUMEN
Production of xylitol from xylose in batch fermentations of Candida mogii ATCC 18364 is discussed in the presence of glucose as the cosubstrate. Various initial ratios of glucose and xylose concentrations are assessed for their impact on yield and rate of production of xylitol. Supplementation with glucose at the beginning of the fermentation increased the specific growth rate, biomass yield and volumetric productivity of xylitol compared with fermentation that used xylose as the sole carbon source. A mathematical model is developed for eventual use in predicting the product formation rate and yield. The model parameters were estimated from experimental observations, using a genetic algorithm. Batch fermentations, which were carried out with xylose alone and a mixture of xylose and glucose, were used to validate the model. The model fitted well with the experimental data of cell growth, substrate consumption and xylitol production.