A process to concentrate coffee extract by the integration of falling film and block freeze-concentration

A comprehensive investigation of the use of freeze concentration appro aches for the concentration of fish protein hydrolysates

Fish protein hydrolysates (FPH) are inherently unstable in their liquid form, necessitating either freezing or dewatering for stabilization. Gentle methods such as freeze concentration can be used to remove water, this can be achieved by freezing water in solution by decreasing the bulk temperature below freezing point and separating pure ice crystals from concentrated solution. This approach serves as an alternative to techniques like evaporation and reverse osmosis for concentrating solutions that have high water content, significant nutritional value, and thermolabile compounds. This is crucial as many bioactive compounds degrade when exposed to elevated temperatures. Another notable advantage of this technology is its potential to reduce energy consumption by up to 40% when integrated into the FPH drying process. Although this technology is currently industrialized primarily for juices, it can achieve concentrations of up to 60°Brix and manage viscosities up to 400 mPa.s. Numerous studies have been dedicated to enhancing design and processes, leading to a 35% reduction in the system's capital cost and a 20% reduction in energy consumption. Moreover, freeze concentration can synergize with other concentration techniques, creating more efficient hybrid processes. This review aims to introduce freeze concentration as a superior option for preserving fish protein hydrolysates, enhancing their stability, and maintaining their nutritional and bioactive qualities.

Progressive freeze concentration of skimmed milk in an agitated vessel: Effect of the coolant temperature and stirring rate on process performance

The aim of this study was to investigate the freeze-concentration of skimmed milk by a progressive freeze concentration process. The progressive freeze concentration procedure was performed at three different temperatures (-5, -10, and -15 ℃) and stirring rates (0, 500, and 1000 r/min). The solids concentration was determined and used for calculations of the efficiency of the process, concentrated yield, and experimental results validation. A general linear model was applied to determine the influence of the two factors studied, namely coolant temperature and agitation speed. In all tests, it was possible to concentrated skimmed milk with total solids content higher (P < 0.05) than ultra-high temperature skimmed milk. The highest concentration (P < 0.05) was achieved at low coolant temperature (-15 ℃) and high agitation speed (1000 r/min). The coolant temperature and the stirring rate both had a significant effect (P < 0.05) on the results of efficiency of the process and concentrated yield. Nevertheless, the parameter that showed the most significant effect in our study was the stirring rate. The tests presented a good fit since the root mean square values were below 25%. The freezing point temperatures of the concentrated milk fractions were lower than that of skimmed milk. Finally, the best-operating conditions in our study were achieved using a high coolant temperature (-5 ℃) and high mechanical stirring (1000 r/min), which was also the variable with the lowest (P < 0.05) retention of solids in the ice fraction. In our study, the progressive freeze concentration technique showed promise as an alternative for the dairy industry since it makes the development of new dairy products possible.