Spray drying is the gold standard for manufacturing dairy powders, due to its ability to maintain nutritional and functional properties and operate at high capacities. It is, however, extremely ene...

Energy usage in the manufacture of dairy powders: Advances in conventional processing and disruptive technologies

Génie industriel alimentaire

This research evaluates the effect of falling film vacuum evaporation on the characteristics of clarified acid bovine milk whey. The clarified acid whey was obtained by microfiltration (ceramic membranes, 0.2 µm cut-off, ∆TMP: 2 bar) and concentrated by a falling film evaporator. The clarified whey composition was mainly protein (0.32 ± 0.06 % w/w), ashes (0.56 ± 0.08 % w/w), soluble solids (5 ± 1 % w/w), and turbidity (16 ± 5 NTU). During the concentration step, the number of cycles changed notoriously for each volume reduction factor (VRF), being four the highest value achieved, with an average number of cycles of 18. The characteristics of concentrates were not affected by differences in the number of cycles, increasing proportionally with the VRF; it could be noticed in the final content that protein, ashes, and °Bx increased linearly around 3.5 times the initial composition. However, turbidity was different for each VRF because of heat treatment during the concentration stage (above 60 °C). A thermal treatment step after ricotta preparation would be advisable to remove the remaining protein. Tukey’s test was carried out at a 95 % CI, revealing statistical differences among means; therefore, there was a change in the characteristics of the final concentrated whey. Regarding color (absorbance), there were no considerable changes during the concentration process.

http://revistacta.agrosavia.co/index.php/revista/article/download/1241/843

Evaluating volume reduction of clarified acid bovine milk whey via falling film vacuum evaporation

The object of this study is a functional fruit-and-berry paste for health purposes with the selection of components (apples, Ziziphus jujuba, blueberries), which are sources of dietary fiber, vitamin C, low molecular weight polyphenolic compounds and phytosterols, which are used as an immunostimulant to create products with cholesterol-lowering effect.  The task to increase the content of these substances is solved by concentrating in a rotary film evaporator (RFE) under mild regime parameters (60...65 °C) to a dry matter (DM) content of 30...32 % for 45...50 s and by the pasteurization of concentrated paste in a scraper heat exchanger (SHE) at a temperature of 95...98 °C followed by packing.
The effective viscosity (Pa·s) of the mixtures of the original purees (DM 16...17 %) and resulting pastes (30...32 %) has been determined and its increase was found in the pastes compared to puree, by 1.65...1.85 times. The obtained data indicate a strengthening of the structure of the resulting functional paste, which, compared to control, has an effective viscosity of 3.6 times more. A significant advantage has a paste containing 45 % of apple; 35 % of Ziziphus jujuba; 20 % of blueberries. It is characterized by an enhanced content of dietary fiber, by 3.8 times; vitamin C, by 2.25 times; low-molecular polyphenolic compounds and tannins, phytosterols. Therefore, it can be used as an immunostimulant to manufacture products with cholesterol-lowering effect.
It was established that in order to effectively conduct the process of concentration in RFE and subsequent pasteurization in SHE, it is rational to grind puree to a particle size within 0.1...0.5 mm. The heat transfer coefficient when concentrating samples with a particle size of 0.5 mm has a higher rate, by 6 %, compared to the sample with a particle size of 1.5 mm. The technology could be introduced at the enterprises of the canning and confectionery industries

http://journals.uran.ua/eejet/article/download/262924/260021

Improving the production technology of functional paste-like fruit-and-berry semi-finished products

The object of the study is a multi-component past-like semi-finished product based on apples, Jerusalem artichokes, cranberries and hawthorn, which are natural nutrients with original properties obtained by cooking at 55–60 °C in an experimental vacuum-evaporator.
The method of production of a multi-component semi-finished product has been improved by keeping hawthorn in a 10...15 % NaCl solution with the addition of 1 % citric acid at 20...25 °C for 30...45 minutes. Blanching with hot steam at a temperature of 105...110 °C is carried out for: apple (2...3 min), Jerusalem artichoke (5...8 min) and hawthorn (4...6 min), and cranberries are blanched with water for 1.5...3 min at temperatures of 80...90 °C. Wiping the components followed by recipe-component blending and boiling at 55...60 °C in an experimental vacuum-evaporator.
According to the organoleptic parameters, the puree blend containing: apple – 35 %, Jerusalem artichoke – 30 %, cranberry – 25 % and hawthorn – 10 % with a yellow-orange color has the advantage. The ultimate shear stress (pureed components, Pa) is: apple – 14, Jerusalem artichoke – 322, cranberry – 75, hawthorn – 445. The boiled paste mixture has an increased viscosity by 3.5 times compared to the control.
The heating of the working chamber and the stirrer of the vacuum-evaporating apparatus is carried out by a film resistive electronic heater of the radiating type, providing stabilization of the temperature effect and a 45 % increase in the boiling efficiency compared to the classic vacuum apparatus. The improved method will expand the range of competitive semi-finished products of a wide range of applications with natural nutrients and regulated rheological and functional properties, which will contribute to the production of food products with an immunomodulating effect

/pdf/improvement-of-the-manufacturing-method-of-multi-component-1fxxko5t.pdf

Improvement of the manufacturing method of multi-component paste-like vegetable semi-finished products with a high degree of readiness

Falling film evaporators (FFE) are widely used in the chemical, refrigeration, petroleum refining, desalination and food industries. In the dairy industry FFE is applied for the concentration of solutions prior to the drying step. Despite the economic importance of the vacuum evaporation process in the manufacture of dairy dried products, the knowledge about the process is mostly empirical. Research aiming to improve the efficiency of the process is therefore necessary. The objective of this PhD project was to characterize experimentally a FFE during the concentration of dairy products by means of thermodynamic and hydrodynamic approaches, in order to study the interactions between the products properties and the operating parameters. A pilot-scale, single-stage falling film evaporator that describes the same process as that of an industrial scale from a hydrodynamic point of view was instrumented and used to establish the mass and energy balances. The evaporation rate and the overall heat transfer coefficient were calculated from the experimental data to follow up the process. A methodology for the determination of the experimental residence time distribution (RTD) functions was developed. RTD functions provide global information about the flow of the products during concentration in a FFE. Increasing of the concentration of skim milk, mass flow rate and the distance covered by the product resulted in an increase in the dispersion of the products particles. The experimental RTD functions were modelled by a combination of two perfectly mixed reactor tanks in series. From the interpretation of this model, two different flows, a main and a minor flow, were identified. The RTD methodology developed on skim milk was applied to sweet whey and lactic acid whey and the study was extended to the formation of fouling during a 5-hour concentration. The mean residence time was more sensitive to identify fouling than the overall heat transfer coefficient and the evaporation rate. This study emphasized the crucial role of process characterization to improve the performance of FFE and product quality.

/pdf/thermodynamic-and-hydrodynamic-characterization-of-the-2stv3o4wgi.pdf

Arlan Caldas Pereira Silveira

Papers

Thermodynamic and hydrodynamic characterization of the vacuum evaporation process during concentration of dairy products in a falling film evaporator