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Conventional yogurt production uses mechanical stirring and milk fermentation. Several factors that affect the quality of yogurt include raw materials and fermentation technology. Yogurt is rich in protein and fat, but it has a short shelf life and is easily damaged. For development, we used ultrasonic waves that could form cavitation waves to form microbubbles and homogenized the mixture so that the reaction occurred more quickly. The aim of the study is to determine the effect of ultrasonic waves and preservatives on the level of respondents' preference for the yogurt's physical properties. The starter bacteria and milk were obtained from a milk cooperative shop in Batu Malang. Yogurt quality was analyzed from the questionnaire concerning the respondent's level of preference which included texture, thickness, aroma, color, and taste. The results show that the presence of ultrasonic waves in the mixing process has an effect on the quality of yogurt. Respondents prefer the physical properties of yogurt, aspect of color, shape, smell, and homogeneity, made with the help of ultrasonic waves. Preservatives (potassium sorbate) can extend the shelf life but carries a minimum influence on the physical properties of yogurt. The yogurt processing with optimum results involves no addition of preservatives but using ultrasonic waves. [ABSTRACT FROM AUTHOR]

In the previous study, the 9-(4-hydroxyphenyl)-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-dione has been successfully synthesized using lime juice as a green catalyst. Condition optimization was still needed to enhance the reaction yield. In this research, the compound has been synthesized using lime juice assisted by ultrasonic irradiation. The use of ultrasonic waves aimed to enhance product yield and reduce reaction time and temperature when lime juice was applied as the catalyst at the reaction. The non-catalyst compound was synthesized using water as a solvent and assisted by ultrasonic irradiation, producing a yield of 45.16%. In contrast, the lime juice catalyst synthesized product brings a higher yield of 89.03%. This study discusses the role of lime juice catalysts in improving yield percentage and decreasing reaction time and temperature. The synthesized compound 1 was in the form of white powder with a melting point of 228-230°C. GC-MS analysis of compound 1 confirms a single peak with a retention time of 15.497 minutes and a peak with an m/z value of 310.1 in.the MS spectrum as molecular ion of the compound. The presence of a phenolic group at the compound induces its antibacterial activity. However, the antibacterial test showed that the compound has weak antibacterial activity against Escherichia coli and no activity against Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

The heterogeneous catalysts in biodiesel synthesis is more environmentally friendly and reusable. Alkaline earth oxides are less alkaline than alkaline oxides. Biodiesel is an alternative fuel, which has been started to be developed as a renewable energy. The aim of this study was to synthesize biodiesel from low-quality crude palm oil (CPO) with heterogeneous catalyst of MgO-K2O using ultrasonic waves. The stages in this study were (a) activation of natural zeolites, (b) refining of low quality of CPO, (c) synthesis of MgO-K2O catalyst at ratio of 10 : 1, 10 : 2, 10 : 3 (MgO : KOH) and (d) transesterification of esterified CPO (variations in the amount of catalyst 10%, 15%, and 20%). This research achieved the optimum conditions for methyl ester synthesis at ratio of 10 : 2 (MgO : KOH) of catalyst composition (15% w/w of oil), and the yield was 88.086%. The character of the methyl ester was in accordance of Indonesian biodiesel standard, therefore, the methyl ester obtained has the potential as biodiesel. The composition of the synthesized methyl ester were 1.96% methyl myristate, 40.42% methyl palmitate, 44.32% methyl oleate, and 7.46% methyl stearate. [ABSTRACT FROM AUTHOR]

Synthesis of methyl ester from tobacco oil (Voor-Oogst) with potassium hydroxide (KOH) catalyst using ultrasonic waves and its potential test as biodiesel had been done. The tobacco seeds were obtained from Probolinggo, East Java, Indonesia. The stages in this study were: 1. Isolation of tobacco seed oil using n-hexane as a solvent; 2. Esterification process; 3. Transesterification with some variation in the KOH concentration as a catalyst; 4. Characterization of the synthesized methyl ester; and 5. Identification of the synthesized methyl ester components by GC-MS. The results showed that the synthesis of methyl esters through the transesterification method using three KOH concentration variation 0.8%, 1% and 2% w/w and ultra-sonic waves produced biodiesel with yields of 77.45%, 84.55%, and 80.72% respectively. According to SNI criteria of biodiesel, methyl esters from tobacco oil met the biodiesel standard with the viscosity of 4.44 cSt, density of 0.865 g/mL, refractive index of 1.45, acid number of 0.56 mg/g. The main constituent of methyl ester of the biodiesel were methyl palmitate, linoleic, oleic and stearic with the percentage of 18.72%; 30.76%; 27.26% and 9.35%, respectively. [ABSTRACT FROM AUTHOR]