INFLUENCE OF SUGAR SUBSTITUTES ON STABILITY OF GRAIN ENERGY BARS DURING STORAGE

Рост алиментарно-зависимых заболеваний, связанных с повышением гликемического индекса, делает актуальной разработку продуктов без сахара. Представляет интерес исследование влияния заменителей сахара на влагопоглощающие характеристики зерновых энергетических батончиков, пользующихся большим спросом потребителей. Объектом исследования были образцы зерновых батончиков без замены сахара – образец 1 (контроль) и с заменой сахара изомальтом и мальтитом – образцы 2 и 3 соответственно. Влагопоглощающие свойства зерновых батончиков анализировали по изотермам сорбции, построенным по моделям Caurie, Khun и Guggenheim Anderson de Boer, при активности воды от 0,1 до 0,9. Установлено, что при активности воды выше 0,6 в образцах 2 и 3 в отличие от контрольного образца происходило резкое увеличение содержания влаги. Значение равновесной относительной влажности для контрольного образца составляло 50%, а для образцов 2 и 3 с заменой сахара – около 60%. После 90 сут хранения образец батончика 2 с изомальтом имел более высокое сенсорное качество (сохранил мягкость и хрустящие свойства) по сравнению с контрольным образцом и образцом 3, приготовленным с мальтитом. Таким образом, замена сахара альтернативными подсластителями в зерновых энергетических батончиках делает их более стабильными при хранении. The increase in the number of alimentary-dependent diseases associated with an increase in the glycemic index makes the development of sugar-free products relevant. It is of interest to study the effect of sugar substitutes on the moisture-absorbing characteristics of grain energy bars, which are in great demand by consumers. The object of the study was samples of grain bars without sugar replacement-sample 1 (control) and with sugar replacement with isomalt and maltitol – samples 2 and 3 respectively. The moisture-absorbing properties of grain bars were analyzed by sorption isotherms constructed according to the Caurie, Khun, and Guggenheim Anderson de Boer models, with water activity from 0,1 to 0,9. It was found that when the water activity was higher than 0,6 in samples 2 and 3, in contrast to the control sample, a sharp increase in the moisture content occurred. The value of the equilibrium relative humidity for the control sample was 50%, and for samples 2 and 3 with sugar replacement – about 60%. After 90 days of storage, the sample of the bar 2 with isomalt had a higher sensory quality (it retained its softness and crunchy properties) compared to the control sample and the sample 3 prepared with maltitol. Thus, replacing sugar with alternative sweeteners in grain energy bars makes them more stable during storage.

Water from Air: Desiccant System Design and Simulation

Air water generators that harvest water from air humidity have the potential to counter the ever-rising problem of drinking water scarcity. There are many different types of air water generation systems that work on various different principles. Desiccant based air water generation systems work on the principle of moisture absorption, consisting of a packed bed dehumidifier that absorbs the moisture from air. This reduces the energy requirement of the system. To discuss the efficiency of the system, it is crucial to understand the working of the packed bed column. In this paper, a mathematical model has been developed for a packed bed dehumidification system using aqueous CaCl2 as the liquid desiccant. This model has been developed using water saturation pressure and equilibrium relative humidity models. The packed bed model has been used to study the effect of various input parameters like air and desiccant flow rate, packing material, relative humidity and desiccant concentration, on the capacity of the desiccant to absorb water from air. The results so obtained can be used to predict the water that can be absorbed by the desiccant in the packed bed column for given inlet conditions.

Direct measurements of the RHeq in salt mixtures including the contribution from metastable phases

Accelerated salt-induced deterioration occurs by frequent changes across the equilibrium relative humidity (RH eq ). Therefore, knowledge of the actual RH eq of a salt mixture has a major impact on preventive conservation to ensure that the relative humidity (RH) does not cause a salt phase transition and in situ desalination as the dissolution of salt is the essential criterion to enable transport of salt (ions) in materials. For decades, it has been possible to determine the RH eq in salt mixtures with the user-friendly, thermodynamic-based ECOS-Runsalt software. However, the ECOS-Runsalt model is challenged by the influence of kinetics along with some limitations in regard to possible ion types and combinations. A dynamic vapor sorption (DVS) instrument is used for the direct measurement of RH eq and to deduce knowledge on the physicochemical nonequilibrium process related to the phase changes in salt mixtures. The experimentally measured RH eq values in this study of NaCl-Na 2 SO 4 -NaNO3, NaNO 3 -Na 2 SO 4 , NaCl-NaNO 3 , NaCl-Na 2 SO 4 , and (NH 4 ) 2 SO 4 -Na 2 SO 4 are in agreement with values from the literature. A comparison with thermodynamically calculated results makes it probable that the phase transition for some salts is significantly influenced by nonequilibrium conditions. The present work bridges some of the existing gaps in regard to accuracy, including the effects of kinetics and the possible ions and combinations that may be found in situ. The proposed method makes it possible to determine a more representative RH eq in relation to real conditions for the improved treatment of salt-infected constructs.

Effects of Post-Harvest Conditions on Sorption Isotherms of Soybeans

This study focuses on the modeling of sorption characteristics of three varieties of soybeans (Akras R2, Lono R2, and Podaga R2). Three pretreatments related to post-harvest conditions were tested on the soybean varieties: (1) freshly harvested soybeans, (2) soybeans subjected to three drying and wetting cycles, and (3) soybeans subjected to three freezing and thawing cycles. The adsorption and desorption experiments were conducted at 5°C, 10°C, 15°C, 20°C, 25°C, and 30°C using a dynamic equilibrium relative humidity (ERH) apparatus. Equilibrium moisture content (EMC) and the corresponding ERH were measured. The parameters calculated for the modified Halsey equation are applicable for storage temperatures above 10°C in the relative humidity (RH) ranges of 10% to 80% for desorption and 30% to 80% for adsorption. No significant differences were found in sorption isotherms among the soybean varieties. However, the soybean varieties responded differently to the different pretreatments (i.e., drying/wetting and freezing/thawing cycles). The adsorption isotherms of Akras and Lono soybeans showed significant differences at 10°C to 30°C when subjected to drying and wetting cycles, while Akras and Podaga soybeans showed significant differences in the same temperature range when subjected to freezing and thawing cycles. The effect of drying and wetting cycles on the desorption isotherms was found only for Akras soybeans at 10°C and 15°C below 63% and 71% RH, respectively, and for Lono soybeans at 25°C and 30°C above 69% RH for both temperatures. In general, the effect of both pretreatments on the sorption isotherms of soybeans was a reduction in EMC of up to 20%, when compared to fresh samples at selected storage temperatures. The findings of this study serve as a primary tool for developing a lookup table for safe storage guidelines for soybeans. Keywords: Equilibrium moisture content, Equilibrium relative humidity, Halsey equation, Oswin equation, Soybeans.

Equilibrium Moisture Characteristics of Egg White Powder at Higher Temperatures

The equilibrium moisture content (EMC) of food material is defined as the moisture content of the material after it has been exposed to a particular environment for an infinitely long period of time. Equilibrium moisture characteristics of Egg White Powder (EWP) was studied at higher temperatures of 50, 60, 70, 80 and 90°C in the equilibrium relative humidity (ERH) range of 10-78% (at seven levels). The standard gravimetric method was used to determine the EMC-ERH relationships of EWP by employing the various saturated inorganic salt solutions. The EMC of EWP at any particular ERH decreased with an increase in environmental temperature. The EMC of EWP ranged from 2.17 to 3.35 at lower ERH value of about 10% whereas the EMC values ranged from 12.07 to 14.80 at higher ERH value of about 78% when the environmental temperature increased from 50°C to 90°C. EMC values of EWP are different than that of the values obtained at lower temperatures, hence useful to understand the thermal processing of EWP at higher temperatures. EMC-ERH data obtained in this study was fit into seven EMC-ERH models namely Henderson, modified Henderson, modified Chung-Pfost, modified Oswin, modified Halsey, modified GAB (Guggenheim, Ander-son and de-Boer) and Chen-Clayton models and were evaluated using mean relative percent error (Pe), standard error of estimate (SEE) and residual plots. The modified Henderson equation described the EMC-ERH relationship of EWP the best, Henderson, and Chen-Clayton equations gave good fit. The heat of vaporization (hfg) of EWP at different moisture contents and temperatures was calculated from EMC-ERH data with the help of the Clausius-Clapeyron equation. The hfg values indicate that the heat of vaporization of EWP increases as the moisture content and temperature decreases and the values are higher than that of the pure water.

Conservation seed physiology of the ciénega endemic, Eryngium sparganophyllum (Apiaceae)

Knowledge of seed dormancy and optimal propagation techniques is crucial for successful ex situ restoration and reintroduction projects, and determining the seed storage behaviour of a species is critical for the long-term conservation of seeds, further supporting future ex situ efforts. Eryngium sparganophyllum (Apiaceae) is a globally critically endangered plant species endemic to ciénega wetlands of southwest North America. To support in situ and ex situ conservation efforts of E. sparganophyllum, we asked (i) how does the embryo: seed (E:S) ratio change over time once imbibed, (ii) how does germination respond with varying periods of exposure to cold (5°C) and warm (25°C) stratification, and concentrations of gibberellic acid (GA3). By answering these questions, (iii) can dormancy class be inferred, and (iv) what storage behaviour category is exhibited? To answer these questions, we collected seeds in Southern Arizona from one of the few remaining wild populations. We measured embryo growth and tested the effects of cold (0–18 weeks) and warm (0 and 4 weeks) stratification, and 0–1000 ppm gibberellic acid on germination. We also tested the effects of cold (−80°C) dry (~20% equilibrium relative humidity) storage on germination. We found that (i) embryos grow inside seeds prior to germination; (ii) compared to control, cold stratification for at least 6 weeks increased germination and warm stratification had no effect; (iii) 1000-ppm GA3 had the highest germination success; (iv) therefore this species exhibits morphophysiological dormancy; and (v) seeds are orthodox and can therefore be conserved using conventional storage methods. This information will aid managers in the propagation of E. sparganophyllum that is crucial for in situ reintroduction and restoration projects, and seed banking represents a critical ex situ conservation strategy for the preservation of this species.

Comparative Analysis of Sorption Isotherms for Wood Pellets and Solid Wood

The published data on equilibrium moisture content vs. equilibrium relative humidity (EMC-ERH) for wood pellet do not cover the range of temperature and relative humidity to which a pellet is exposed to during its storage and handling. A few published EMC-ERH relations covering a wider range of temperatures and relative humidity are available for solid wood (lumber) and wood chips. The question is whether the data for solid wood is applicable to wood pellets. For this research, we examined the sorption isotherms of wood pellets and solid wood. The analysis shows that EMC for solid wood is higher than the EMC for wood pellet for a relative humidity larger than 30%. The slope of EMC-ERH isotherm for solid wood in the range of 30%-70% is slightly steeper than the slope of isotherm for wood pellet, indicating the pellet’s EMC is less sensitive to ERH when compared to EMC-ERH for solid wood. Keywords: EMC, ERH, Densified biomass, Equilibrium moisture content, Equilibrium relative humidity, Solid wood, Wood pellets.

Equilibrium Moisture Content of Hazelnut Husks, Shells, and Kernels

Hybrid hazelnuts that are predominately a cross between the American hazelnut () and the European hazelnut () are being grown and evaluated as part of an effort to develop a thriving hazelnut industry for the Upper Midwest of the U.S. Along with this plant development effort, researchers are investigating and assessing various harvesting and processing methods and equipment in an effort to create a robust and food-safe production industry. One harvesting alternative is to pick hazelnut clusters off plants before the nuts fully ripen and fall to the ground, an approach that requires greater attention to drying. Whether entire clusters are dried or the nuts are separated from the husks prior to drying is a decision that will be influenced by the drying requirements and potential uses for these hazelnut fractions. To this end, a study was undertaken to establish desorption isotherms for the husks, shells, and kernels of hybrid hazelnuts grown in the Upper Midwest. Clusters were hand-picked from shrubs in Wisconsin and immediately placed in 18 different controlled environments (six different relative humidity levels at three different temperatures). Actual moisture conditioning took place over saturated salt solutions in specially fabricated biomaterial moisture conditioning units. After a six-week period during which the clusters reached equilibrium with their environment via desorption, they were separated into husk, shell, and kernel fractions and returned to their respective conditioning units. After another six weeks in the conditioning units, the moisture content (MC) of each fraction was determined by oven-drying at 103°C for 48 h. Under equilibrium conditions, the kernel MC was found to be only 37% of that for shells, whereas the equilibrium moisture content (EMC) values for husks were on average 14% greater than those for shells. On a dry basis, the average cluster mass was 32.9% husk, 43.9% shell, and 23.2% kernel. Likewise, on a dry basis, the average whole nut mass was 65.5% shell and 34.5% kernel. The desorption data were fit to the Modified Henderson, Modified Chung-Pfost, Modified Halsey, Modified Oswin, and Modified GAB equations. Overall, the best fit to the experimental data was provided by the Modified Chung-Pfost equation with parameters determined using equilibrium relative humidity (ERH) as the dependent variable in regression analyses. For ERH values above 0.70, the temperature-modified form of the GAB equation is recommended for predicting desorption EMC values for hazelnut fractions. Keywords: Desorption, Equilibrium moisture content, Equilibrium relative humidity, Hazelnuts, Kernels, Nuts, Shells, Water activity.

Mathematical modeling of drying the pulped coffee (Coffea arabica l.) at different air conditions

The aim of the study was to describe the drying kinetics of washed coffee (Coffea arabicaL.) and evaluate the best mathematical model to fit the experimental drying data conducted with different air humidity (40 %, 50 %, and 60 %) and temperatures (23 °C, 40 °C, and 60 °C). The fruit shakes were standardized washing, separation, and manual selection of green coffees, pass cane, and green buoy. Then, approx. 150 L of coffee cherries were pulped and taken directly to the yard. Drying the washed coffee was completed in a mechanical dryer and yard. The obtained results showed that the different conditions of the ambient air significantly influenced the processes of drying pulped coffee. The water content of the hygroscopic equilibrium of pulped coffee is directly proportional to the water activity and relative humidity, decreasing with increasing temperature, for the same value of equilibrium relative humidity. The Oswin model was best represented by the hygroscopicity of the pulped coffee, while the Midilli model shows the best fit to describe the drying curves of the washed coffee. The effective diffusion coefficient increases with increasing temperature of the drying air and reducing of relative humidity, being described by the Arrhenius equation. The aim of the study was to describe the drying kinetics of washed coffee (Coffea arabica L.) and evaluate the best mathematical model to fit the experimental drying data conducted with different air humidity (40 %, 50 %, and 60 %) and temperatures (23 °C, 40 °C, and 60 °C). The fruit shakes were standardized washing, separation, and manual selection of green coffees, pass cane, and green buoy. Then, approx. 150 L of coffee cherries were pulped and taken directly to the yard. Drying the washed coffee was completed in a mechanical dryer and yard. The obtained results showed that the different conditions of the ambient air significantly influenced the processes of drying pulped coffee. The water content of the hygroscopic equilibrium of pulped coffee is directly proportional to the water activity and relative humidity, decreasing with increasing temperature, for the same value of equilibrium relative humidity. The Oswin model was best represented by the hygroscopicity of the pulped coffee, while the Midilli model shows the best fit to describe the drying curves of the washed coffee. The effective diffusion coefficient increases with increasing temperature of the drying air and reducing of relative humidity, being described by the Arrhenius equation