Bioactive compounds extraction from oak chips into rice spirit: New application of ultrasound

Abstract

This research proposed using power ultrasound to produce a phenolic-rich rice spirit from oak chips. Independent parameters were ultrasound power (0, 275, and 550 W), oak-spirit ratio (1.00:1.25, 1.00:2.50, and 1.00:5.00), and time (1 h to 14 days). Dependent factors were color parameters (L*, a*, b*, C*, and ΔE), pH, alcohol content, total acidity (TA), total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) value, total energy consumption, and specific energy consumption (SEC). Furthermore, oak chips were analyzed using a scanning electron microscopy (SEM) to elaborate on the extraction mechanism. Results showed that ultrasound enhanced ΔE, C*, TPC, and DPPH. TA ranged between 0.008% and 0.014% and was not affected by sonication. Alcohol content and pH decreased by increasing the sonication time. Also, increasing ultrasound power and time, as well as the oak-spirit ratio, enhanced the phenolic content. The greatest TPC was 138.95 ± 2.21 mg gallic acid equivalent per L which was achieved at 550 W/136 min/oakspirit ratio of 1.0:2.5. Besides, ultrasound saved more than 99% of processing time.Moreover, decreasing the oak-spirit ratio and increasing input power increased the SEC. SEM revealed that the sonication power significantly affected the surface of oak chips, and 550 W treatment caused the highest damage to the oaks, converting the surface from smooth to cracked porous. This study provided a scalable platform for an innovative product enriched with antioxidants and phenolic compounds. Practical ApplicationUltrasound treatment yielded a potentially health-promoting rice spirit from oak chips, and essential information regarding the effects of processing parameters on product quality parameters and energy consumption was revealed. For example, it was found that alcohol content and pH values decreased by increasing sonication time. On the other hand, increasing sonication power, time, and the oak-spirit ratio increased phenolics. Sonication saved more than 99% of processing time and altered the oak surface. Besides, specific energy consumption increased by decreasing oakspirit ratios and increasing input power. This study was performed in collaboration with a winery in Taiwan, and the technology was transferred and implemented in the industry.