Design and Development of Innovative Steam Injection for High-Temperature Short-Time Liquid Foods

Jet impingement has been effective in reducing the process time and improvement of product quality in various industrial applications, such as textile and paper drying, electronic cooling, glass quenching and food processing. The current work applied innovative steam injection to liquid food continuous sterilization. The multiple impingement jets of steam and product came together in the impingement tank. The effects were investigated on the Reynolds number, steam temperature and jet-to-target spacing (H/d), sterilization temperature and heat transfer efficiency in water and pineapple juice tests. The Reynolds number was based on the nozzle configuration and liquid flow rate. The study investigated product injection plates formed using two, three or four circular holes (diameter 2 mm), steam injection plates with six, nine or twenty circular holes (diameter 1 mm), steam temperatures of 120, 125 or 130 °C and H/d values of 1, 3, 5 or 7. The different options were tested with water to determine the optimal conditions, and then tested with pineapple juice. The results showed that the optimal conditions from water testing that provided the highest heat transfer efficiency occurred with two jet nozzles, six steam injection plates, a steam temperature of 120 °C and an H/d value of 1.

Gas Hold-Up and Mass Transfer in a Vessel with an Unsteady Rotating Concave Blade Impeller

The steady mixing of gas-liquid systems is used where a large development of the interfacial area is required. However, the presence of gas in the liquid reduces the efficiency of mass transfer by reducing the mixing power, due to the creation of gas formations behind the impeller blades and the reduction in density. The efficiency of mass transfer can be increased by using a concave blade impeller or unsteady mixing. Mass transfer efficiency studies for these impellers and unsteady mixing are limited. This paper presents an analysis of the influence of the impeller construction on the gas hold-up and volumetric mass transfer coefficient kLa. Impellers with a different number of concave blades, and with alternatively arranged concave blades, were analyzed. The obtained results were compared with the standard flat blade turbine. The obtained results indicate that the arrangement of the concave blades has the greatest effect on reducing the gas hold-up and kLa. Higher values were obtained for the four-bladed and six-bladed impellers. A comparison of the gas hold-up rate for the unsteady and steady mixing has shown that for steady mixing greater gas hold-up is achieved. The volumetric mass transfer coefficient for unsteady mixing is also greater compared to steady mixing, indicating greater efficiency in mass transfer.

Study on Behavior of the Heat Exchanger with Conically-Corrugated Tubes and HDD Baffles

Baffles with holes in different diameters (or HDD baffles) and conically-corrugated tubes are respectively longitudinal flow baffle and high-efficiency heat exchange tubes proposed by the author. In this paper, vibrations of tube bundles with HDD baffles and fluid flow as well as heat transfer inside conically-corrugated tubes were numerically simulated, and the heat exchanger with conically-corrugated tubes and HDD baffles was tested for the heat transfer efficiency. It is found that compared with the traditional segmental baffles, tube bundle vibrations in heat exchangers, if using the HDD baffles, can be significantly reduced. Regarding heat transfer efficiency, conically-corrugated tubes are much better than smooth tubes and even better than other high-efficiency heat transfer tubes. Compared with the traditional heat exchangers, heat exchangers constructed with conically-corrugated tubes and the HDD baffles can provide better heat transfer efficiency and less tube bundle vibration.

Процессы передачи энергии в эвлитите Sr-=SUB=-3-=/SUB=-Y(PO-=SUB=-4-=/SUB=-)-=SUB=-3-=/SUB=-, по отдельности и одновременно легированном ионами Tb-=SUP=-3+-=/SUP=- и Tm-=SUP=-3+-=/SUP=-

In this work the optical spectroscopy and the energy transfer processes involving the Tb3+and Tm3+ ions, have been studied in eulytite double phosphate hosts of the type Sr3Y(PO4)3 doped with various amounts of the two Ln ions. It has been found that several energy transfer and cross-relaxation processes are active in this class of materials, upon excitation in the 5D4 level of Tb, and in the 1G4 one of Tm. In particular, a Tb→Tm transfer of excitation has been found to quench strongly the 5D4 level of Tb. This process occurs with a transfer efficiency increasing from 0.08 to 0.62, for a donor concentration of 2 mol%, and an acceptor concentration increasing from 2 to 15 mol%. The emission spectra are strongly affected by the presence of Tb⟷Tm energy transfer, and Tm→Tm cross relaxation processes.

Evaluation of Salmonella Biofilm Cell Transfer from Common Food Contact Surfaces to Beef Products

Meat contamination by Salmonella enterica is a serious public health concern. Available studies have suggested that biofilm formation at processing plants and the contaminated contact surfaces might contribute to meat contamination. Since bacteria transfer from contact surfaces to food products via direct contact has been deemed as the most common transmission route that could lead to contamination, we evaluated the effect of Salmonella biofilm forming ability, contact surface materials, and beef surface tissue types on Salmonella biofilm transfer from hard surfaces to beef products. Salmonella biofilms developed on common contact surface stainless steel (S.S) and polyvinylchloride (P.V.C) were transferred consecutively via direct contacts of 30 sec each to either lean muscle or adipose tissue surfaces of 15 pieces of beef trim. Our results showed that Salmonella biofilm cells could be effectively transferred multiple times from contact surface to beef trim as enumerable Salmonella cells could be detected on most of the meat samples. Bacterial biofilm forming ability had the most significant impact (p<0.05) on transfer efficiency as the strong biofilm forming strains not only transferred higher amounts of bacteria after each contact, but also contaminated more meat samples with enumerable Salmonella cells compared to the weak biofilm formers. Contact surface materials could affect transferability as Salmonella biofilms on S.S surface appeared to transfer more efficiently compared to those on P.V.C surface. Conversely, the two types of meat surface tissues showed no significant difference (p>0.05) on biofilm transfer efficiency. Furthermore, biofilm - contacted beef trim without enumerable Salmonella cells all exhibited positive Salmonella prevalence after enrichment. Our study demonstrated the high potential of Salmonella biofilms on common contact surfaces to cause product cross contamination in meat processing plants.