Low-temperature Vacuum Drying Research Articles

The Content of Biologically Active Substances in Phytobiotics Used for Agricultural Animals and Poultry

Medicinal plants are producers of many biologically active substances – compounds that can influence biological processes in animals; such compounds include cardiac glycosides, saponins, sterols, carotenoids, polyphenols, alkaloids, vitamins, quinones, as well as substances with specific aroma, taste and color. Objects of the research were the extracts of purple coneflower (Echinacea purpurea), maral root (Leuzea carthamoides), holy thistle (Silybum marianum) and marigold (Calendula officinalis) obtained by low-temperature water-ethanolic extraction followed by low-temperature vacuum drying of the extracts. The content of biologically active substances was determined in accordance with the standard methods of chemical analysis for phytobiotic substances. As shown by the results of the studies, phytobiotic substances contain ascorbic acid, polysaccharides, tannins, carotenoids, phytosterols, fructose and inulin. They also contain many flavonoids, which, presumably, efficiently alter the economic-useful qualities of agricultural animals and poultry. The phytobiotical feed additives may indirectly control the intestinal microflora, supporting the internal protective mechanisms of the animal organism. The use of phytobiotical feed additives in the diet of farm animals and poultry is rationally substantiated, and contributes to abandoning the use of antibiotics in the fodder.

건조방법에 따른 새송이버섯, 이슬송이버섯, 잎새버섯의 품질 특성

This study compared the quality and drying characteristics of dried king oyster mushroom (Pleurotus eryngii), shiitake mushroom (Lentinus edodes GNA01) and maitake mushroom (Grifola frondosa) slices obtained by sundrying, hot-air drying (40, 50, 60℃), low-temperature vacuum drying (20, 25, 30℃), heat-pump dehumidifying drying (30, 40, 50℃), and freeze drying. The quality changes investigted included color, browning degree, hardness, general components, β-glucan. Color changes in king oyster mushroom during freeze drying were less than that between control (raw) and treated mushrooms. Compared with other drying methods, low-temperature vacuum drying of shiitake mushroom resulted in less color changes. Browning degree differed significantly between the different drying methods. As temperature increased, low-temperature vacuum drying resulted in decreased browning while heat-pump dehumidifying drying resulted in increased browning. In king oyster mushroom, hardness increased with temperature under hot-air drying, low-temperature vacuum drying and heat-pump dehumidifying drying. In shiitake mushroom, hardness increased with increasing temperature under hot-air drying and heat-pump dehumidifying drying. β-glucan content after drying was found to be between 28.29 and 39.39% in king oyster mushroom, 23.05 and 29.48% in shiitake mushroom and 16.10 and 24.51% in maitake mushroom.

Optimization of Solid-state Fermentation Process and Development of Biocontrol Agent Based on Cassava Residue from Streptomyces Microflavus

In this article, solid-state fermentation of low-cost Streptomyces microflavus is studied by using cassava residue, rice husk and other agricultural solid waste resources as the substrate to prepare biopharmaceuticals [1]. The experiment results showed that the Streptomyces microflavus’ optimum solid-state fermentation medium and conditions includes the following components: cassava residue 89.85%, rice husk 10%, KH2PO4 0.05%, NaCl 0.05%, MgSO4 0.05%. The fermentation temperature is controlled at about 30 °C, the initial water content is around 50%, initial pH is 6.6-7, the material thickness is 5cm, the inoculation amount is 7.5%, the cultivation time is 4 days, and the spore yield is 4.8*109 cfu/g. The survival rate of Streptomyces microflavus’ spores is 75%, which compared with blank conditions increased by 30% after low temperature vacuum drying. The work of this paper provides some theoretical guidance for the large-scale industrial production of Streptomyces, which has valuable application in agricultural field.

Solid - state Fermentation Technology of Paecilomyces lilacinus and Development of Agricultural Biocontrol Agent Based on Agricultural Waste Resources

Studied the solid-state fermentation of low-cost Paecilomyces lilacinus by using mushroom residue, rice husk and other agricultural waste resources as the substrate. The results showed that the optimum solid fermentation medium includes the following components: mushroom residue: bran =1:1, soybean meal 1.5%, glucose 1.2%, KH2PO4 0.2%, MgSO4 0.08%, CaCO3 0.7%. The culture temperature was 28 °C, the loading thickness was 5 cm, the inoculation amount was 8%, the culture time was 7 days, and the spore yield could reach1.35×1010 cfu/g. The addition of 3 ‰ shrimp and crab shell powder, the fermentation product chitinase activity was significantly improved. The effect of adding 5 ‰ trehalose on the spore survival rate of Paecilomyces lilacinus increased by 89.3% by low-temperature vacuum drying. The work of this paper provides some guidance for the industrial production and application of Paecilomyces lilacinus.

Spatially-confined electrochemical reactions of MoO3 nanobelts for reversible high capacity: Critical roles of glucose

MoO3-based layered structural oxides have long been exploited as promising electrode materials for lithium-ion batteries (LIBs), due to their high energy density and high cyclability. However, the limited interlayer spacing and their low electronic conductivity lead to capacity loss and low rate performance. This raises the crucial question whether good electrical conductivity of MoO3 with expanded interlayer spacing could be obtained to satisfy the requirements of high specific capacity and long durability. To solve this problem, herein, we introduce glucose for the modification of MoO3 powders by low-temperature vacuum drying. It is found that MoO3 can be readily reduced, bonded and spontaneously intercalated by glucose (MoO3−x@G). More importantly, glucose functioned as a cage to hold the pulverized MoO3−x pieces, while the subsequent conversion reaction of between Li2O, Mo and LixMoO3 occurred in confined space, which maintained electrodes structural integrity. As a result, the synthesized MoO3−x@G exhibits superior specific capacity and rate capability compared to pure MoO3. Furthermore, we demonstrate that the exceptional performance of MoO3−x@G could be ascribed to the capacitive contribution and high reversible reaction. Our results give a unique insight into understanding the detailed electrochemical conversion processes of conversion-type electrode materials for application in high-performance LIBs.

A Simple Method to Prepare Raw Dehydrated Potato Flour by Low-Temperature Vacuum Drying

Abstract A simple method called low-temperature vacuum drying (LTVD) was used to produce a novel dehydrated potato flour called raw dehydrated potato flour (RDPF). Preparing RDPF by LTVD at 60°C, 70°C and 80°C in both slice and dice shape was investigated. Potato samples in dice shape are easier dehydrating than in slice shape, the starch granules of RDPF maintain ellipsoid shape as the native potato starch. The best temperature of LTVD to prepare the RDPF is around 70°C according to CIE chromaticity results. Dehydrate at 60°C in dice shape, 88.37% of the trypsin inhibitor activity of the fresh potato is maintained. The Mixolab curve shows that the RDPF has some similar rheological properties of the wheat flour. Protein undenatured, starch ungelatinized, with the high performance of processing properties, RDPF has a number of potential applications in the potato staple food manufacture.

A new dewatering technique for stingless bees honey

One of the problems faced in stingless bee honey storage is spoilage by the fermentation process occurs in honey due to its high water content. There are a few techniques available currently, but they are time consuming and there is excessive heat involved in the process. The temperature of the process must be kept low because excessive heat can deteriorate nutrition value and biochemical content in honey. Hence, a new method of honey dewatering was developed using a Low Temperature Vacuum Drying (LTVD) with induced nucleation technique. The objective of this research is to investigate the performance of a LTVD with induced nucleation to reduce the water content in honey. First, the honey was placed in a pressure vessel, and then air was removed. Then, the honey was slightly heated at 30 oC and the water content before and after the experiment was measured by a refractometer. The steps were repeated until the water content reached below 20%. It was found that the LTVD method improved the water removal rate significantly with an average of 0.15% of water content per minute. That is 3 times much faster than the conventional method of low temperature heating by Tabouret. Higher temperature during dewatering process improved the dewatering rate significantly. It can be concluded that LTVD is a promising option in tackling the high water content in stingless bee honey issue.

Effects of the Low Temperature Vacuum Drying Process on Drying Curve and Physico-Chemical Properties of Astringent Persimmons

Effects of the Low Temperature Vacuum Drying Process on Drying Curve and Physico-Chemical Properties of Astringent Persimmons

Production for High-vitality Starter Culture of <i>Lactobacillus plantarum</i> NDC 75017 by High Cell-density Cultivation and Low-temperature Vacuum Drying

Production for High-vitality Starter Culture of <i>Lactobacillus plantarum</i> NDC 75017 by High Cell-density Cultivation and Low-temperature Vacuum Drying

Drying Kinetics and Survival of Bacteria Suspensions of L. paracasei F19 in Low-Temperature Vacuum Drying

The aim of this work was to investigate the influence of process parameters on water content, water activity, survival rate, and membrane integrity during low-temperature vacuum drying for Lactobacillus paracasei F19. Early stationary-phase cells were dried for different lengths of time. The drying rates did not affect the cell survival and the membrane integrity. Additionally, it could be seen that the membrane integrity strongly correlated with the water activity. However, the loss of membrane integrity was sublethal at water contents between 40 and 20%; beyond this range water content reduction started to become lethal due to the irreversible loss of cell membrane integrity.

Low-Temperature Vacuum Drying of Natural Gardenia Yellow Pigment

The effects of operational parameters, that is, drying temperature, feed solution layer thickness, and level of vacuum, on product qualities and drying kinetics for low-temperature vacuum drying of Gardenia yellow pigment were studied. Temperature had the most significant effect on product quality and drying time. The optimal operating conditions to yield the best product quality were obtained as heating temperature, 35°C; layer thickness, 7 mm; and vacuum level, 0.09 MPa. Simulation results showed that the well-known Page model gave the best prediction. The effective diffusion coefficients for Gardenia yellow pigment solutions (20% wb) were estimated from the drying curves in the range 8.45 × 10−9 m2/s at 35°C and 1.10 × 10−8 m2/s at 55°C.

Combined influence of fermentation and drying conditions on survival and metabolic activity of starter and probiotic cultures after low-temperature vacuum drying

The influence of low temperature vacuum drying process parameters on the survival, metabolic activity and residual water content of three different bacterial strains (Lactobacillus paracasei ssp. paracasei, Lactobacillus delbrueckii ssp. bulgaricus and Bifidobacterium lactis) was investigated. Shelf temperature and chamber pressure were varied and optimized by response surface methodology with regard to survival and residual water content. It is shown that the survival rate after low temperature vacuum drying is comparable to that of freeze drying. Based on the optimization experiments the combined influence of fermentation pH and drying process parameters was studied for the most detrimental and the best process condition, respectively. The results show that interactions between process and fermentation conditions have to be taken in account and that these influences are highly strain specific.

Influence of process conditions and fermentation pH on the drying result of starter and probiotic cultures in the low-temperature vacuum drying

Influence of process conditions and fermentation pH on the drying result of starter and probiotic cultures in the low-temperature vacuum drying

Variation in Drying Behavior and Final Moisture Content of Wood during Conventional Low Temperature Drying and Vacuum Drying of Betula pendula Timber

Conventional and vacuum drying experiments were conducted on Betula pendula timber, which was sawn from trees felled during three different seasons. The influence of the wood procurement season on drying behavior differed, on the one hand, between the drying phases above and below 30% moisture content in the conventional drying, and, on the other hand, between the conventional and vacuum drying methods. During the first steps of the conventional drying process, relative humidity in the kiln, as well as drying time and drying rate, varied according to the felling season. Variations in environmental conditions outside the kiln and the seasonal variation in the physical properties of the wood were presumed to be the reasons for differences in drying behavior. The difference in moisture content gradient, i.e., the difference in final moisture content between the inner wood and the surface layer of boards, was greater in conventionally dried timber than in vacuum-dried timber. In conventionally dried timber there was a clear seasonal variation in the gradient of final moisture content, which was greatest for winter-felled wood. The premature drying of the surface layer during the first steps of the conventional drying process of winter-felled wood was the reason for the higher gradient of moisture content. Storage of wood as logs decreased the standard deviation of the final moisture content.

Study of the processes of mechanical-thermal treatment of food dispersed materials

The paper presents experimental data for the processes of low-temperature vacuum drying and grinding of thermolabile materials in devices with spring members.

Technology of processing electrolytic copper powder by low temperature vacuum drying: H. Wenxian, W. Limin (Central Inst. of Non-Ferrous Metals, Beijing, China). PM Technol., vol 13, no 4, 1995, 265–267h. (In Chinese.)

Many food materials are dried to enhance shelf-life. Drying is an energy-intensive process, and accurate drying models could be used in real time process control of drying equipment to drive cost optimizations. However, most physics-based models suffer from two shortcomings: they require thermo-physical properties of the food materials to be known a priori, and they usually neglect material shrinkage due to moisture loss. In this work, we first develop a simplified physics-based transport model to predict temperatures and moisture content and corresponding spatial and temporal shrinkage during low temperature air drying process, where volumetric shrinkage is dominated by moisture loss. This model agrees well with experiments conducted by us (reported in this paper) as well as with those conducted by others (taken from the literature) on food samples. Further, using the validated modelling framework, we have developed an experimentally validated deep learning-based artificial neural network (ANN) model for properties' estimation. This ANN model is designed to estimate solid density, initial porosity, and initial water saturation of a given food material, using temperature and moisture data from a set of simple experiments with error less than 1%. Using these predicted parameters as input, the physics-based model can predict temperature and moisture for real-time drying to within 5% accuracy. The method proposed in this work could play an important role in industrial drying process optimisation and will find wide applications in the food processing industry.