Different bioactive flavonoid compounds including catechin, epicatechin, rutin, myricetin, luteolin, apigenin and naringenin were obtained from spearmint (Mentha spicata L.) leaves by using conventional soxhlet extraction (CSE) and supercritical carbon dioxide (SC-CO2) extraction at different extraction schemes and parameters. The effect of different parameters such as temperature (40, 50 and 60 °C), pressure (100, 200 and 300 bar) and dynamic extraction time (30, 60 and 90 min) on the supercritical carbon dioxide (SC-CO2) extraction of spearmint flavonoids was investigated using full factorial arrangement in a completely randomized design (CRD). The extracts of spearmint leaves obtained by CSE and optimal SC-CO2 extraction conditions were further analyzed by high performance liquid chromatography (HPLC) to identify and quantify major bioactive flavonoid compounds profile. Comparable results were obtained by optimum SC-CO2 extraction condition (60 °C, 200 bar, 60 min) and 70% ethanol soxhlet extraction. As revealed by the results, soxhlet extraction had a higher crude extract yield (257.67 mg/g) comparing to the SC-CO2 extraction (60.57 mg/g). Supercritical carbon dioxide extract (optimum condition) was found to have more main flavonoid compounds (seven bioactive flavonoids) with high concentration comparing to the 70% ethanol soxhlet extraction (five bioactive flavonoids). Therefore, SC-CO2 extraction is considered as an alternative process compared to the CSE for obtaining the bioactive flavonoid compounds with high concentration from spearmint leaves.

Pitaya commonly known as dragon fruit is very popular of its intense color, constituent minerals, vitamins, and antioxidant properties. In this study, physiochemical properties of whole pitaya fruit powder as influenced by 2 different maltodextrin concentrations (20 and 30%) and 4 different inlet temperatures (145, 155, 165, and 175 o C) were carried out. As inlet temperature increased moisture content and water activity decreased and this change was apparent at high concentration of maltodextrin. The best spray drying condition in relation to betacyanin content was 155 o C inlet temperature and 20% maltodextrin concentration. Concerning the flowability, all factors and their levels resulted in poor flowing powder. From nutritional point of view, pitaya fruit powder was found rich in protein, fat, ash, fiber, and antioxidant. This study indicated that the pitaya fruit powder produced from whole pitaya fruit has potential to use as natural coloring agent and a health supplement.

In the present study, ultrasound-assisted extraction of crude oil from winter melon seeds was investigated through response surface methodology (RSM). Process variables were power level (25–75%), temperature (45–55 °C) and sonication time (20–40 min). It was found that all process variables have significant (p < 0.05) effects on the response variable. A central composite design (CCD) was used to determine the optimum process conditions. Optimal conditions were identified as 65% power level, 52 °C temperature and 36 min sonication time for maximum crude yield (108.62 mg-extract/g-dried matter). The antioxidant activity, total phenolic content and fatty acid composition of extract obtained under optimized conditions were determined and compared with those of oil obtained by the Soxhlet method. It was found that crude extract yield (CEY) of ultrasound-assisted extraction was lower than that of the Soxhlet method, whereas antioxidant activity and total phenolic content of the extract obtained by ultrasound-assisted extraction were clearly higher than those of the Soxhlet extract. Furthermore, both extracts were rich in unsaturated fatty acids. The major fatty acids of the both extracts were linoleic acid and oleic acid.

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Ultrasound treatment was applied on whey protein concentrate suspension prior to foaming and being mixed into batter for eggless cake baking. The improvement of batter and baked cake made using ultrasound treated whey protein were measured in terms of aeration, rheological and textural properties. Baked cakes formulated with untreated whey protein suspension at varying concentrations between 10 and 20 % were compared with ultrasound treated whey protein up to 25 min at 60 % amplitude. Visualized images of aerated cake products using x-ray tomography technique supported the findings of improved batter in terms of density decrease by 5 %, and viscosity, consistency index, storage modulus, and loss modulus increase by 31, 57, 33, and 21 %, respectively. For baked cakes, volume increase was 18 %, and density, hardness, and chewiness decrease was 18, 65, and 64 %, respectively, when compared to those made using untreated whey protein. Image analysis presented a higher number of smaller gas cells in the aerated baked cakes structure using ultrasound treated whey protein.

The optimization of pink guava was executed using central composite face-centred design to optimize the spray drying parameters of inlet temperature, maltodextrin concentration (MDC) and feed flow (FF). The experimental results were significantly (<0.01) fitted into second-order polynomial models to describe and predict the response quality in terms of the final moisture, particle size and lycopene with of 0.9749, 0.9616, and 0.9505, respectively. The final moisture content significantly (<0.01) decreased with increasing inlet temperature and MDC, whereas the particle size increased. In contrast, the lycopene content significantly (<0.01) decreased with the higher temperature and increased with increasing MDC. However, according to multiple response optimization, the optimum conditions of 150°C inlet temperature, 17.12% (w/v) MDC and 350 mL/h FF-predicted 3.10% moisture content, 11.23 μm particle size and 58.71 mg/100 g lycopene content. The experimental observation satisfied the predicted model within the acceptable range of the responses.

The bioactive flavonoid compounds of spearmint (Mentha spicata L.) leaves were obtained by using supercritical carbon dioxide (SC-CO 2 ) extraction. Extraction was carried out according to face-centred central composite design, and independent variables were pressure (100, 200 and 300 bar), temperature (40, 50 and 60°C) and co-solvent amount (3, 6 and 9 g/min). The extraction process was optimized by using response surface methodology for the highest crude extraction yield of bioactive flavonoid compounds. The optimal conditions were identified as 209.39 bar pressure, 50.00°C temperature and 7.39 g/min co-solvent amount. The obtained extract under optimum SC-CO 2 condition was analysed by high-performance liquid chromatography. Seven bioactive flavonoids including catechin, epicatechin, rutin, luteolin, myricetin, apigenin and naringenin were identified as major compounds. The results of quantification showed that spearmint leaves are potential source of antioxidant compounds.