Optimisation of a pilot‐scale spray drying process for probiotic yoghurt,using response surface methodology

The influence of drying air temperatures, drying air flow rate and feed flow rate on percentage survival rate (% SR) of starter and probiotic bacteria, moisture content, water activity and colour of probiotic yoghurt powder produced using a pilot‐scale spray dryer was investigated. Optimisation of spray drying conditions was achieved based on the desirability value. Results showed that inlet air temperature, drying air flow rate, feed flow rate and outlet air temperature of 150 °C, 478 m³/h, 2 L/h and 63.3 °C, respectively, were optimal conditions to produce powder that meets quality specifications and with a satisfactory% SR.     

Development of phase change material assisted evacuated tube solar dryer: Investigation of thermal profile,drying characteristics,and functional properties of pumpkin slices

The present work aimed to develop a phase change material-assisted evacuated tube solar dryer (PCM-ETSD) and experiments were performed with and without PCM for drying pumpkin slices. Thermal performance, drying characteristics, and quality attributes were analyzed with and without PCM at different airflow rates: 34.64 kg/h, 51.96 kg/h, and 69.28 kg/h. The average temperature elevation between the ambient and drying chamber was achieved at 29.62 °C to 36.33 °C and 25.64 °C to 28.93 °C without and with PCM-assisted drying respectively. PCM-ETSD extended the drying period by 2 h and maintained the temperature ranges from 50.78 °C to 61.29 °C after sunshine hours. The PCM-ETSD reduced the moisture content of pumpkin slices by 4–5% and 8% more as compared to without PCM and sun drying respectively. Drying rate and effective moisture diffusivity are enhanced with the increase of airflow rate in the drying process and higher without PCM-assisted drying followed by PCM and sun drying. The total phenolic content and total flavonoid content are higher in PCM-assisted drying and continuously decreased with the increases in airflow rate in both drying processes. Antioxidant activity and total carotenoid content are higher in PCM-assisted drying. FTIR analysis confirmed the presence of active functional groups and phenols in dried pumpkin. The inferior color changes were observed in PCM-assisted drying of pumpkin slices. The developed PCM-ETSD could be capable of drying other food commodities on a pilot scale after sunshine with retention of quality attributes.     

Mathematical modeling and performance analysis of thin layer drying of bitter gourd in sensible storage based indirect solar dryer

An indirect forced convection solar dryer integrated with porous sensible heat storage medium was developed. The effect of porous thermal storage and mass flow rate of air on the performance of the system for drying bitter gourd was studied. The experimental setup consists of a blower, solar flat plate collector with corrugated absorber plate (2 m²) and a drying chamber. The thermal storage medium (pebble) is placed below the corrugated absorber plate, in the air passage as a porous medium. The experiments have been carried out with various mass flow rates of air and different drying models have been used for explaining the drying behaviour of sliced bitter gourd. The result shows that, (i) the initial moisture content 92% (w.b) of bitter gourd was reduced to 9% (w.b) in 7 h in the proposed drying system, while it was 10 h for open sun drying, (ii) the maximum specific moisture extraction rate was observed as 0.215 kg/kWh at the mass flow rate of 0.0636 kg/s and the corresponding specific energy consumption was 4.44 kWh/kg, (iii) the collector and drying efficiency of the system were 22% and 19% respectively. The two term model and Midilli–Kucuk model are most suitable for indirect solar dryer and open sun drying in terms of statistical parameter respectively. The drying inside sensible heat storage based indirect dryer was more consistent and produced better quality product as compared to open sun drying.Industrial relevance

• •Every year post harvest losses are increasing rapidly due to the lack of storage facilities.
• •Solar dryers are the most suitable technology that can be easily availed at low cost and in small scale and it can be used as an income generation option for farmers and women in rural areas.
• •The role of solar dryers in food processing industries is significant especially in developing countries in the following areas
  • oFor preserving fruits and vegetables
  • oDairy industries
  • oAgricultural crop drying
  • oTimber drying
  • oIndustrial waste drying
• •The utilization of thermal storage medium in the solar dryers is being focused much for the reasons of extending the availability of the system for operation and to achieve better quality of the products.

     

Development of infrared-assisted hybrid solar dryer for drying pineapple slices: Investigation of drying characteristics,mass transfer parameters,and quality attributes

The research aims to the development and performance evaluation of an infrared-assisted hybrid solar dryer (IR-HSD) for drying pineapple slices. The IR-HSD contains an evacuated tube solar collector, blower assembly, drying chamber, infrared heater, phase change material (PCM) chamber, etc. The study investigates and compares the thermal profiling, drying kinetics, mass transfer parameters and quality attributes of pineapple slices dried using different methods, such as direct drying, phase change material (PCM)-assisted drying, PCM + IR-assisted drying, and sun drying. The average temperatures achieved inside the drying chamber for direct drying and PCM-assisted drying were 60.16 °C and 57.29 °C, respectively, while the temperature reached 60 °C for PCM + IR assisted drying. The average drying rate in PCM + IR drying was higher than in direct and PCM-assisted drying methods. The best-fitting models were the Modified Page model for direct and PCM + IR-assisted drying and the Midilli-Kucuk model for PCM-assisted and sun drying. The higher effective moisture diffusivity for PCM + IR-assisted drying was 2.59 × 10⁻⁹ m²/s, followed by direct and PCM-assisted drying. Similarly, the convective mass transfer coefficient obtained was 1.085 × 10⁻⁷ m/s, 8.321 × 10⁻⁸ m/s, and 1.381 × 10⁻⁷ m/s for direct, PCM-assisted, and PCM + IR-assisted drying, respectively. The superior quality attributes such as total flavonoid content (TFC), total phenolic content (TPC), and antioxidant activity were observed in all drying approaches with retention of colour except open sun drying, which decreased significantly. FTIR spectroscopy analysis confirmed the presence of different bioactive, including aromatic compounds, phenols and hydrocarbon functional groups. The infrared-assisted hybrid solar drying of pineapple slices showed a better drying process and quality attributes.     

Exergy,energy and economic analysis of a V-groove assist rotating tray type solar cabinet dryer for drying potato chips

In this present work we have studied the exergy, energy and economic performance of a V-grooved type air collector with rotating trays type of solar cabinet dryer for drying potato chips in the sunny days of winter season at Bhubaneswar (20.2961° N, 85.8245° E), Odisha. The obtained results from this experiment were also compared with the performance of a flat plate air collector with rotating trays used in the same dryer. The average energy efficiency of the solar air collector (SAC) and drying chamber (DC) was found to be 73.3% and 24.8% in case of V-grooved and 60.1% and 19.3% in case of plane collector respectively. The average exergy inflow, outflow, loss and efficiency of the drying chamber in case of V-grooved collector was found as 19.7 W, 11.82 W, 7.88 W and 58.14% where as it was 22.3 W, 12.96 W, 9.34.88 W and 56.12% in case of plane collector respectively. Similarly the average exergy inflow, outflow, loss and efficiency of the SAC in case of V-grooved was found as 845 W, 20.1 W, 824.9 W and 1.99% where as it was 830 W, 22 W, 808 W and 2.28% in case of plane collector respectively. The average exergy and energy efficiency of the V-grooved type chamber are found to be 3.47% and 22.17% higher respectively as compared to plane collector. The air temperature at the inlet and outlet of the SAC and DC mainly affects the exergy value.     

Quality improvement of non-sulphited mango slices by drying at high temperatures

An optimum drying routine for producing non-sulphited mango slices has been developed. The interaction of essential drying parameters (air temperature, air velocity, dew point, slice thickness and drying time) on water activity (a_W) and browning was determined. Microbiological stability of the dried product was achieved at a moisture content of 17% wet base (w.b.) corresponding to a_W = 0.6. Browning was monitored by the red colour shade of the product (CIE-Lab chromaticity coordinate a*). Drying air temperature and drying time were shown to be the primary factors influencing product colour and a_W. In contrast to common practice, drying for about 6 h at elevated air temperature (80 °C), instead of 50 or 60 °C for a longer time, was optimal, since significant colour changes of the mango slices were not observed even without the use of any chemical or thermal pre-treatment. Moreover, at increased temperature, drying time was considerably shortened from about 9 h to 6 h, resulting in significant extension of the drying capacity.

Industrial Relevance

The suggested process concept for dried mango slices based on high-temperature drying is of utmost significance for the international marketing of dried fruit products. Chemical pre-treatments such as sulphitation often used to minimise quality deficiencies could be avoided. Sulphitation has been recently under critical consideration with respect to allergen labelling of foodstuffs implemented by EU-Member States in November 2004 (Directive 2003/89/EC) [Directive 2003/89/EC. Official Journal of the European Union, 25.11.2003, pp. L308/15–18 (http://europa.eu.int/eur-lex/pri/en/oj/dat/2003/l_308/l_30820031125en00150018.pdf)]. Export quality was improved and the drying process simplified, improving the utilisation of drying capacities. Particularly referring to an application of the technology in small- and medium-sized enterprises with limited investment possibilities, the suggested novel drying procedure in mango processing aimed at the optimisation of well-established simple drying methods instead of choosing technically more sophisticated technologies.     

Effect of microwave vacuum drying and hot air drying on the physicochemical properties of durian flour

Unripe durian cv. Monthong was subjected to microwave vacuum drying (MVD) at 1200, 1600 and 2200 W and hot air drying (HAD) at 40, 50 and 60 °C to produce durian flour. Drying rate of MVD and HAD was 0.34–0.58 kg water kg dry solid^?1 min^?1 and 0.02–0.06 kg water kg dry solid^?1 min^?1, respectively. An increase in drying rate by either increasing hot air temperature or increasing microwave power decreased the degree of crystallinity from 21.95% to 2.31% and from 7.72% to 4.05%, respectively. Moreover, the increased drying rate caused a decrease in endothermic enthalpy (ΔH_gel) and pasting properties. Starch content of the durian flour was 41.40–47.03%. The starch granule morphology of durian flour was disrupted which indicated gelatinisation of flour during drying. Due to a short drying process, the MVD flour had less a*‐value (P ≤ 0.05) than the HAD flour.     

Application of simulation in determining suitable operating parameters for industrial scale fluidized bed dryer during drying of high impurity moist paddy

A systematic approach has been developed for selecting the suitable drying parameters to be used for drying of high moisture and high impurity paddy with an industrial fluidized bed paddy dryer (10–20 t h⁻¹ capacity) based on targeted specific air flow rate and residence time during two typical paddy drying seasons. A mathematical model was developed by modifying an existing model and was simulated and validated with observed industrial drying data as well as data reported in the literature. Comparison between the observed and simulated results showed that the mathematical model is capable of predicting outlet paddy moisture content and air temperature well. Suitable operating parameters were determined for reducing any initial paddy moisture content (mc) down to 24–25% dry basis (db), the safe mc level after fluidized bed drying to maintain rice quality, to achieve maximum possible throughput capacity of the dryer with corresponding energy consumption. Based on these criteria, bed thickness at 10 cm, specific air flow rate of 0.05 kg kg⁻¹ s⁻¹ (for corresponding bed air velocity of 2.3 m s⁻¹), air temperature of 150 °C and residence time of 1.0 min were found to be suitable drying conditions for reducing paddy mc from 30 to 24.30% (db) in one season while the maximum throughput capacity of 15.7 tonne per hour (t h⁻¹) might be achieved. The specific electrical and thermal energy were 0.48 and 6.15 MJ kg⁻¹ water evaporated, respectively. On the other hand, the dryer capacity was found to be limited to 7.4 t h⁻¹ during drying paddy of higher initial mc (35% db). This approach might provide easy and comprehensive guidelines for selecting suitable sets of operating parameters for any industrial fluidized bed dryer at its possible maximum throughput capacity for drying of freshly harvested high moist paddy with a high level of impurities.     

Study on microencapsulation of curcumin pigments by spray drying

Curcumin has strong coloring power, safety and innocuity, comprehensive pharmacological function, but its low stability and water insoluble limit its application. Curcumin microcapsules were prepared by spray-drying process using porous starch and gelatin as wall material here. Results showed optimal condition as follows: the ratio of core and wall material of 1/30, embedding temperature of 70 °C, embedding time 2 h, inlet gas temperature of 190 °C, feed flow rate 70 mL/min and drying air flow 70 m³/h, at which the microencapsules had good encapsulation efficiency. The stability of microencapsulation curcumin against light, heat, pH was effectively improved and its solubility was increased greatly. This study would be helpful to the industrial application of curcumin.     

Microencapsulation of flax oil with zein using spray and freeze drying

Microencapsulation of flax oil was investigated using zein as the coating material. Central Composite Design - Face Centered was used to optimize the microencapsulation with respect to zein concentration (x₁) and flax oil concentration (x₂) using spray drying. Also, freeze drying was carried out at two zein:oil ratios. The quality of microcapsules was evaluated by determining encapsulation efficiency, flowing properties (Hausner ratio), and evaluating the morphology with scanning electron microscopy. The response surface model for microencapsulation efficiency showed a high coefficient of determination (R² = 0.992) and a non-significant lack of fit (p = 0.256). The maximum microencapsulation efficiencies were 93.26 ± 0.95 and 59.63 ± 0.36% for spray drying and freeze drying, respectively. However, microcapsules prepared by spray and freeze drying had very poor handling properties based on the Hausner ratio. The bulk density decreased with an increase in zein concentration at the same flax oil concentration. The morphology of the flax oil microcapsules depended on the zein:flax oil ratio and the process used for microencapsulation. Flax oil microcapsules prepared by spray drying appeared to be composed of heterogeneous spheres of various sizes at high zein:flax oil ratios. Microcapsules prepared by freeze drying resulted in agglomerated small spheres. These microcapsules might find a niche as functional food ingredients.     

Performance analysis of drying of green olive in a tray dryer

This paper deals with the performance evaluation of a single layer drying process of green olives in a tray dryer using exergy analysis method. Green olive was used as the test material being dried. Drying process was realized at four different drying air temperatures (40, 50, 60 and 70 °C) and a constant relative humidity of 15%. The effects of temperatures and mass flow rates were investigated. Maximum exergy efficiency of the drying chamber was obtained at a temperature of 70 °C and a drying air mass flow rate of 0.015 kg/s with 0.0004 kg/s of olive. The exergy efficiency values were found to be in the range of 68.65%–91.79% from 40 °C to 70 °C with drying air mass flow rates of 0.01 kg/s–0.015 kg/s.     

Efficacies of Garlic and L. sakei in Wine‐Based Marinades for Controlling Listeria monocytogenes and Salmonella spp. in Chouriço de Vinho,a Dry Sausage Made from Wine‐Marinated Pork

Chouriço de vinho is made from roughly minced (10 to 30 mm) pork and fat, seasoned with a marinade made from wine, salt, garlic, and other facultative seasonings used according to the recipe of each producer. The batter is maintained at 4 to 7 ºC for 24 to 48 h. It is then stuffed into natural thin pork gut, cold smoked and matured at a low temperature for 1 to 4 wk. The effect of garlic used in wine‐based marinade and a starter culture of indigenous Lactobacillus sakei on the behavior of Listeria monocytogenes and Salmonella spp. in the processing of chouriço was investigated. The garlic (as powder and fresh juice) was found to contribute (P < 0.05) to the control of both pathogens in broth. Garlic dose, as tested within the usual limits used for seasoning, did not impact the reduction of pathogens. Garlic‐wine‐based marinade and a starter culture of indigenous L. sakei contribute to controlling L. monocytogenes and Salmonella spp. in the processing of chouriço. Their presence was responsible for the loss of viability of L. monocytogenes and Salmonella spp. following 5 d of drying, even sooner than situations where no garlic was used. The results of the present work show that the use of a wine‐based marinade with garlic has an important role in ensuring the safety of the product.     

Investigating the effect of food trays porosity on the drying process

Improving the dynamics of airflow behavior in the drying system is essential for improving its efficiency. In this study, the impact of the porosity of the plum-filled drying trays on the airflow behavior inside the chamber is investigated. Three configurations of constant porosity (30%, 50%, 70%), and 4 additional configurations of porosity varying linearly along trays 1 and 2 as a function of the x-axis are evaluated. To model the trays as a porous medium, the Power-low mathematical model was used, with the built-in parameters C₀ and C₁ were given experimentally. Both were formed as a subroutine in C++ and integrated into the CFD code, as was done for the integration of unsteady weather parameters. The CFD method used for visualizing and analyzing the airflow behavior in the drying chamber has been previously validated with the experimental result. The obtained results indicate that the average temperature of the drying trays reaches a maximum of 316,91 k at tray 1 for a porosity of 50% and an inlet velocity of 0.1 m/s. For the case of non-uniform trays porosity, it was found that for low air inlet velocity of 0.1 m/s, the velocity difference ΔV is generally low in cases (b) and (d), where it is equal respectively to 0.02 m/s and 0.01 m/s for tray 1, and 0.01 in both cases for tray 2. While for high air inlet velocity of 1 m/s the difference ΔV in both trays reaches 0.17 m/s.     

Microwave assisted fluidized bed drying of nutmeg mace for essential oil enriched extracts: An assessment of drying kinetics,process optimization and quality

The drying mechanism of the myristicin enriched nutmeg mace has been optimized in a microwave assisted fluidization bed dryer (MWFBD) through multiple linear regression (MLR) and artificial neural network (ANN) modeling. The developed drying technique overcomes the non-uniformity heating problems in microwave heating and prolonged drying in fluidized bed drying. During the novel method of drying selected input variables were drying air temperature (DT) (40–50 °C) and microwave power (MP) (480–800 W) and output variables involving colour, oil yield, and myristicin quantity have been investigated by a continuous air velocity of 5.1 m/s. Six mathematical models about one to four conditions have fitted with an experimental design. Suitable enforcement of such models was evaluated through statistical measures. The coefficient of determination (R²) of MLR varied from 0.89 to 0.98, and the sum of squared error (SSE) varied within 6 × 10⁻³ to 158.18, while R² of ANN fluctuated from 0.82 to 0.95, and the mean squared error (MSE) varied between 0.006 and 0.1450, which shows MLR design performance superior than ANN design. The processing conditions of 48.24 °C DT and 637.431 W MP with a drying time of 1.3 h were identified as optimum conditions with a desirability value of 0.98 to obtain maximum oil yield (13.38%) and good colour (L* (20.83), a* (17.34), b* (8.62)) of nutmug mace. Moreover, no myristicin (5.92%) degradation was observed compared with the sun and convective drying. Among the tested models, page and logarithmic models gave a better prediction of moisture ratio.     

A convective multi-flash drying process for producing dehydrated crispy fruits

The aim of this work was to evaluate the application of a convective multi-flash drying process (CMFD) to producing dehydrated and crisp fruits. To accomplish this process, samples of banana (Musa sapientum L.) or mango (Mangifera indica L.) were heated to 60 °C by hot air, and a vacuum pulse was applied, which resulted in dehydration by a combination of convective drying and flash evaporation. Banana processed by CMFD had a moisture content of 0.293 g/g (dry basis) and a_w = 0.272 after 3 h of processing. Mango had a moisture content of 0.09 g/g and a_w = 0.359 after 4 h of processing. Puncture tests on fruits dehydrated by CMFD and on commercial freeze-dried fruits showed strain-force curves with many peaks (jagged curves). For CMFD much smaller global shrinkage was observed. These results indicate that the CMFD process can be applied for producing crispy fruits and is an alternative to the freeze-drying process.     

Application of cold filamentary microplasma pretreatment assisted by thermionic emission for potato drying

Cold filamentary microplasma (CFM) pretreatment assisted by thermionic emission (TE) is a promising, cold drying technology for agricultural products. Such novel pretreatment method based on local electroporation process in the air gap. Brief theory and treatment mechanism are explained. A fractional factorial design 3³ was used to determine the effect of CFM treatment assisted by TE parameters such as pulse frequency (F = 40, 80 and 120 Hz), pretreatment duration (D = 60, 120 and 180 s) and temperature of thermionic source (T = 700, 850 and 1000 °C) on drying time and drying rate of potato samples. Maximal CFM pretreatment effect was observed at frequency of 80 Hz, treatment duration of 120 s and temperature of thermionic source of 1000 °C, and the corresponding drying rate and drying time were 35·10⁻⁵ (kg/kg s⁻¹) and 130 min. The use of CFM treatment had minor effects on the main quality characteristics (total sugar and starch content) of potato samples. Fourier-transformed infrared spectroscopy confirmed the absence of any modifications of functional group composition of potato samples after CFM pretreatment. Results indicate that cold pulsed filamentary microplasma can enhance the drying rate and decrease drying time without changes in quality characteristics.Practical applicationsCold filamentary microplasma pretreatment assisted by thermionic emission can improve the efficiency of potato drying. Furthermore, it has potential application for reducing energy consumption in drying. CFM pretreatment could be potentially applied for agricultural products drying.     

The effect of osmosis pretreatment on hot‐air drying and microwave drying characteristics of chili (Capsicum annuum L.) flesh

Chili flesh pretreated with or without osmotic dehydration (OD) was dried in the hot‐air drying (AD) oven at 50–80 °C or in the microwave drying (MD) oven at 60–180 W. Results showed that the samples osmotically treated in mixed solution (10% salt + 50% sucrose) had the best dehydration effect as compared with single salt or sugar solutions. During the drying process, osmotically treated samples had one falling‐rate period and their effective moisture diffusivities (D_eff) showed a rapidly linear increase with the decrease in moisture content, while directly drying samples showed a three‐phase falling‐rate period and their D_eff increased gradually at the initial period and then rapidly at the final period. When the moisture content decreased, the activation energy increased gradually; however, for AD after OD, it decreased. Among all the processes, MD at 60 W after OD presented the largest vitamin C retention rate and the best colour difference, needing less drying time.     

Spray‐drying of pomegranate juice with prebiotic dietary fibre

The prebiotic fibres, resistant dextrin and fructooligosaccharides (FOS), were studied for use as drying‐aid agents for the spray‐drying of concentrated pomegranate juice, a low‐caloric juice containing interesting health‐related compounds. Resistant dextrin was the best drying‐aid agent as only 0.5 g g_CPJ^?1 of resistant dextrin was needed to avoid powder stickiness, compared with 1 g g_CPJ^?1 of maltodextrins and 1.5 g g_CPJ^?1 of fructooligosaccharides. The best conditions for spray‐drying a concentrated pomegranate juice (62.6% dry matter) using the resistant dextrin (NUTRIOSE) were 1.25 g_NUTRIOSE g_CPJ^?1 and 0.10 g_CPJ g_solution^?1, a liquid feed rate of 1.08 L h^?1 and an air temperature of 160 °C. Powders were easily solubilised in water, while storage at 25 °C maintained the pomegranate bioactive components, and there were no stickiness problems for at least 2 months. Resistant dextrin could be used with all kind of fruit juices in substitution of maltodextrins, and the resulting prebiotic powders could be employed for formulating novel functional foods.     

Effect of drying methods on the reactivity of chitosan towards Maillard reaction

The effect of drying methods on chitosan reactivity towards Maillard reaction during storage of dried chitosan–lactose systems was investigated. Two different structural forms of chitosan, scaffold and microspheres, were prepared. Then they were dried by lyophilization or using supercritical fluid technology (SF-CO₂) and stored with lactose under controlled temperature conditions (60 °C) and water activity (a_w = 0.65). The drying method produced slight modifications on the chitosan structure especially in samples submitted to SF-CO₂ treatment. Differences were more evident in the reactivity of chitosan–lactose systems during storage. Maillard reaction development was assessed by quantification of a new compound which originated from the acid hydrolysis of Amadori compounds (NFMD) resulting from chitosan–lactose interactions, and not detected in the acid hydrolysates of freshly prepared chitosan-lactose systems. Maillard reaction was influenced by different factors such as the manner of lactose addition, structure of chitosan (microspheres and scaffolds) and drying method. Lyophilized chitosan in the form of microspheres with lactose, presented the highest values of NFMD (428.45 mg/100 g of sample). The determination of this compound could be used as an index of the progress of Maillard reaction.     

Modelling the Dynamic Inactivation of the Probiotic Bacterium <Emphasis Type="Italic">L. Paracasei</Emphasis> ssp. <Emphasis Type="Italic">Paracasei</Emphasis> During a Low-Temperature Drying Process Based on Stationary Data in Concentrated Systems

In order to better understand inactivation of cells during a drying process, the inactivation kinetics of concentrated Lactobacillus paracasei ssp. paracasei (F19) was measured under stationary conditions for different combinations of water activities and temperatures in a water activity range of a _w = 0.23–a _w = 0.75 and temperatures between 4°C and 50°C. It was shown that the inactivation kinetics of the probiotic bacterium L. paracasei at moderate temperatures could, for all conditions, be formally described by a first-order reaction with activation energies that are much lower than for thermal inactivation (E _a = 61 kJ/mol). With regard to the water activity, the reaction rate constants exhibit a maximum inactivation rate at intermediate water activity a _w = 0.52. As this behavior has direct implications for the stability of cells in a drying process, the stationary data were used to model the inactivation during test vacuum drying processes, where both temperature and water activity dynamically change. It is shown that—depending on the drying rate—dynamic effects have to be taken into account when modeling the survival during drying. Nevertheless, the model based on stationary inactivation data is capable to predict the characteristics of inactivation during a drying process. Therefore, it can serve as basis to optimize the drying process with regard to maximum survival of cells. However, a further refinement of the model with regard to the drying rate is necessary.