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Drying Principles and Practices of Cocoa Beans
Published in Hii Ching Lik, Borém Flávio Meira, Drying and Roasting of Cocoa and Coffee, 2019
Ching Lik Hii, Abhay S. Menon, Choon Lai Chiang
Product quality such as acidity has been studied tremendously in the past by many researchers (Duncan et al., 1989; Holm and Aston, 1993; Jinap et al., 1994; Jinap and Zeslinda, 1995; Hashim et al., 1999). High acidity is known to mask the cocoa flavor, and it is associated with a fast drying rate under high temperatures due to the greater retention of volatile acids in dried beans. Acetic acid is the predominant volatile acid constituting 95–98% of the total volatile acids. The loss of acetic acid by evaporation is greater during sun drying as compared to high-temperature artificial drying. Therefore, sun-dried cocoa beans are known to have a higher pH value (less acidic) as compared to artificially dried beans. Acidity in sun-dried beans are typically registered at pH = 5 or above.
Anaerobic Sludge Digestion
Published in Jr. Malina, F. Joseph, Frederick G. Pohland, Design of Anaerobic Processes for the Treatment of Industrial and Municipal Wastes, 2017
Jr. Malina, F. Joseph, Frederick G. Pohland
Daily evaluation of the pH, volatile acid concentration, alkalinity of the sludge, and the carbon dioxide content of the gas is imperative to good digestion and relatively simple and inexpensive analytical techniques are available. Electronic pH meters are available and relatively simple to use. A direct titration method of evaluating the volatile acid concentration has been developed. This method consistently yields results that are higher than those obtained by the distillation methods. However, since relative values are important in digester control, this shortcoming of the direct titration method is not significant. Alkalinity may easily be estimated by titrating the sample with a standard sulfuric acid solution to an end point of pH = 4.5. The color of the supernatant frequently precludes the use of any indicator solutions in this analysis.
Biological stabilisation of sludge
Published in Bhola R. Gurjar, Vinay Kumar Tyagi, Sludge Management, 2017
Bhola R. Gurjar, Vinay Kumar Tyagi
There are several indicators, which can reflect the performance of anaerobic digesters. The reduced production of methane and a corresponding increase in the CO2 content can be a result of increase in volatile acid concentration, and decreases in the alkalinity and pH of the digester content indicate imbalanced anaerobic treatment operation. Several other factors like sudden change in temperature, organic loading, composition of feed sludge, or toxic loading, or a combination of these can also hamper the anaerobic activity. At the normal anaerobic digestion condition of pH between 6.6 and 7.4 and CO2 content of 30 to 40%, the bicarbonate alkalinity will be in the range 1000 to 5000 mg/L as CaCO3. The concentration of bicarbonate alkalinity in the digester content should be about 3000 mg/L as CaCO3.
Hybridization of freeze drying and impacts on drying kinetics and dried product quality of kedondong fruits
Published in Drying Technology, 2022
Cheak Theng Ee, Ching Lik Hii, Sze Pheng Ong, Chung Lim Law, Choon Hui Tan
Most of the panelists rated all the dried kedondong samples had “too little” sweetness (percentage range 64% − 86%) due to the identity of the fruit itself which is naturally sour. However, panelists rated FD samples with the highest JAR score (32%) among all the samples. Comparison with sourness attribute showed that both HA and IR samples obtained lower JAR scores (26% and 20%) which could be caused by the higher temperature (60 °C) that evaporated some of the volatile compounds (mainly acetic acid). [43] Acetic acid is a highly volatile acid found in food[44] and contributed to the sourness flavor and odor of kedondong samples. Majority of the panel also rated “too little” sourness at 50% and 68%, respectively, for HA and IR samples.