latent heat of vaporization for selected foods and crops

Cenkowski, S., Jayas, D.S., and Hao, D. 1992. Latent heat of vaporization for selected foods and crops. Can. Agric. Eng. 34:281-286. The equation for latent heat of vaporization was estab lished based on published equilibrium moisture content curves for main crops and selected foods. For moisture content (mc) above 0.2 db, there is little difference between the heat of vaporization from the grain kernels, hfg*, and that of free water, hfg. Below 0.2 db, this difference increases significantly for grains such as corn and rice. For the other grains (wheat, barley, bean, peanut kernel, soybean, sorghum), the ratio of hfg*/hfg increases at moisture contents below 0.12 db. There is a significant difference in hfg*/hfg results between durum wheat and soft or hard wheat. The latent heat of vaporization of free water is not significantly different from the latent heat of vaporization of water for celery, cloves, and eggs above 0.10 mc db and above 0.15 mc db for chamomile tea and horse radish. The hfg*/hfg ratios for starchy gels are 1.35 to 1.50, which were the highest of the tested crops and foods, for the moisture range between 0.11 and0.16db

Development and comparison of two models to predict survival rates of young larvae of Stegobium paniceum (L.) (Coleoptera: Anobiidae) under heat treated temperatures

Predicting mortality or survival rate of insects at heat treatment temperatures is critical for commercial heat treatment of food and storage facilities. Two models were developed to predict the survival rate of young larvae of drugstore beetle, Stegobium paniceum (L.) (Coleoptera: Anobiidae) under steady state or transient temperature condition: modified fundamental kinetic model and modified complementary log-log transformation model. Published young larvae mortalities and raw data of the temperature history, determined at different heat treatment temperatures, were used to develop these models. The models were verified and compared by using the field data collected in a medium sized mill. Both of the developed models overestimated the insect mortality in the mill when temperature was > 53°C and underestimated insect mortality when temperature was < 50°C. The lowest mean of the absolute difference between the predicted and measured insect mortality in the mill was 16.7±1.1% which was generated by using the modified complementary log-log transformation model. The possible reason of this divergence from the model is discussed.Keywords: Stegobium paniceum (L.), Survival, Heat treatments, Modeling

Modelling of population dynamics of insects in any ecosystem with several distributions of insect development: A Review: Presentation

Predicting the occurrence of insects with a high accuracy requires the estimation of insect development time and the variation among individuals for each life stage and species under different environmental conditions such as fluctuating temperature, variation of relative humidity, different body sizes and stages of the insects, levels of crowding, and food supply. This review summarized the modeling methods of population dynamics of insects with several distributions of insect development, assumption and prediction accuracy of these developed models, and disadvantages and advantages of these modelling methods. These modeling methods include degree day model, nonlinear model, and distribution delay models. The structure of most common models are cohort, Leslie matrix, simulation, and individual based. The relationships among the modeling assumptions, effects of temperature, and other environmental factors, and structures of the developed models were examined. A new modelling approach such as physiological-biological time scale and chaos theory was suggested.Predicting the occurrence of insects with a high accuracy requires the estimation of insect development time and the variation among individuals for each life stage and species under different environmental conditions such as fluctuating temperature, variation of relative humidity, different body sizes and stages of the insects, levels of crowding, and food supply. This review summarized the modeling methods of population dynamics of insects with several distributions of insect development, assumption and prediction accuracy of these developed models, and disadvantages and advantages of these modelling methods. These modeling methods include degree day model, nonlinear model, and distribution delay models. The structure of most common models are cohort, Leslie matrix, simulation, and individual based. The relationships among the modeling assumptions, effects of temperature, and other environmental factors, and structures of the developed models were examined. A new modelling approach such as physiological-biological time scale and chaos theory was suggested

Nanotechnology – an emerging technology for use in agricultural and food research

Abstract Nanotechnology, the science of building atomic, molecular or macro-molecular sized materials, devices, structures or systems is finding applications in different fields. The technology is presently utilized by the chemical, health care, biotech, and manufacturing industries. In the pharmaceuticals, drugs with nano-sized particles are highly efficient with minimal side effects. Micro-scale mechanical and electro mechanical devices are determined to be highly sensitive, durable, and less expensive. Nanotechnology has potential applications in agricultural and food engineering such as exploring biological life processes, monitoring plant and animal health, analyzing and determining product qualities, developing novel materials from agricultural products, and reducing environmental pollutions. This short article reviews the present applications of nanotechnology in other industries and explores its potential applications in agricultural and food industries

Vertical movement of adult rusty grain beetles, Cryptolestes ferrugineus, in stored corn and wheat at uniform moisture content

Vertical movement and distribution of Cryptolestes ferrugineus (Coleoptera: Laemophloeidae) adults in stored wheat and corn were studied in small (0.1 x 0.1 x 1 m) and large (0.6 m diameter and 1.12 m high) columns. The adults were introduced at the top, middle, and bottom of the small columns with a uniform moisture content (wheat: 14.5 ± 0.1%, corn 13.5 ± 0.1%, 15.5 ± 0.1%, and 17.5 ± 0.1%) at 27.5 ± 0.5°C. When introduced at different locations, adults showed a similar distribution in stored grain bulk with a uniform temperature and moisture content of 14.5% for wheat or 15.5% for corn. Adults showed downward displacement over 24 h when corn moisture was lower than 15.5%, but they did not show downward displacement when moisture content was 17.5%. The upward or downward movement might partially be caused by a drift effect due to beetles sliding between seeds and the displacement of the adults might be the combined effect of walking and falling during their movement. The hydrophilic behavior plus the drift effect explain why the beetles had a faster downward dispersal in the 13.5% corn than in the 15.5% and 17.5% corn and a slight upward displacement in 17.5% corn because they were more active at the lower moisture contents. Adults had a similar movement and distribution in both the small and large wheat columns

Models to predict mortality of Tribolium castaneum (Coleoptera: Tenebrionidae) exposed to elevated temperatures during structural heat treatments

Novel thermal death models were developed with certain assumptions, and these models were validated by using actual heat treatment data collected under laboratory conditions at constant temperatures over time and in commercial food-processing facilities where temperatures were dynamically changing over time. The predicted mortalities of both young larvae and adults of the red flour beetle, Tribolium castaneum (Herbst), were within 92–99% of actual measured insect mortalities. There was good concordance between predicted and observed mortalities of young larvae and adults of T. castaneum exposed to constant temperatures in laboratory growth chambers and at variable temperatures during structural heat treatments of commercial food-processing facilities. The models developed in this study can be used to determine effectiveness of structural heat treatments in killing young larvae and adults of T. castaneum and for characterizing insect thermotolerance

Assessment of fan control strategies for in-bin natural air-drying of wheat in Western Canada

. 2014. Assessment of fan control strategies for in-bin natural air-drying of wheat in Western Canada. Canadian Biosystems Engineering/Le génie des biosystèmes au Canada 56: 3.25-3.36. Grains (common term referring to cereal grains, oilseeds, pulses) are usually harvested at high moisture content and then dried to straight grade (dry) or safe storage moisture levels. Grain drying in freestanding, corrugated galvanized steel or welded steel bins using natural air is the most cost effective drying method with optimum grain quality. Adverse weather conditions and inappropriate fan control strategies may result in poor drying, higher drying cost (electricity and fuel), and grain spoilage. Several traditional fan control (continuous ON, only Day ON, only Night ON) and automated fan control (Natural Air Drying (NAD) and SelfAdapting Variable Heat (SAVH)) strategies were investigated using IntegrisPro model software (OPIsystems Inc. ) and supplemental heat on drying performance were studied. High moisture wheat (18-20%) can only be dried effectively with sufficient airflow rate (0.78, and, 1.04 m 3 min -1 t -1 ) and early drying start date (September 15 th or earlier). Without automated control, Continuous ON fan control was a better control strategy. The SAVH control strategy gave the optimized results in terms of fan run hours, target moisture, moisture spread, and shrink (over-drying). The Night ON fan control strategy gave the poorest drying results