Kinetics of Drying and Physical-Chemical Quality of Peach cv. Hubimel

Padilha

et al. 2021

J Food Process Preserv

The effects of different hydrothermal pretreatments on the physical chemical characteristics and drying kinetics of red rice starch (Oryza sativa L.) were investigated.The hydrothermal pretreatments chosen include the cooking, autoclave, and steam explosion processes. To obtain the starch in powder form, the pastes were dried at a temperature of 50°C with an air speed of 1.0 m/s. The mathematical models (empirical and diffusive) were adjusted to the experimental data. The starches were submitted to extraction yield, color, water binding capacity, and proanthocyanidins. The values for the diffusivity are between 3.08 × 10 −7 and 2.74 × 10 −6 m 2 /min for treatments. The pretreatments of cooking in the grain and autoclave in the starch gave better results than the other studied treatments (formulations), presenting shorter drying time (450 and 510 min) and higher yield (48.60% and 53.54%), respectively. With the application of pretreatments, it is possible to save energy and reduce thermal damage. Novelty impact statement:The results obtained in this study reveals the application autoclave pre-treatment in red rice starch effectively saves energy and reduces thermal damage as the drying time is shortened. In addition, the drying process information can be used when designing future new equipments. Highlights• The effects of different hydrothermal pre-treatments on the physical chemical characteristics and drying kinetics of red rice starch (Oryza sativa L.) were investigated.• The hydrothermal pre-treatments included the cooking, autoclave and steam explosion processes.• The pre-treatments of cooking (grain) and autoclave (starch) gave the best results, presenting shorter drying time (510 and 450 min) and higher yield (53.54% and 48.60%), respectively. | INTRODUC TI ONRice is a staple food consumed in many countries around the world due to its nutritional composition (Pereira-Caro et al., 2013). Presenting a series of pigmented varieties, among which red rice has attractive characteristics such as high content of proteins, minerals, vitamins, starch, and bioactive compounds (anthocyanins, proanthocyanidins, and carotenoids) (Sumczynski et al., 2016;Butardo et al., 2019).One of the carbohydrates most found in rice is starch, a polysaccharide that exhibits interesting properties because of its biodegradability, biocompatibility, and nontoxicity (Afolabi et al., 2012).

Section: Resultsmentioning

confidence: 94%

mentioning

confidence: 98%

Impact of hydrothermal pretreatments on physicochemical characteristics and drying kinetics of starch from red rice ( Oryza sativa L.)

Almeida

Padilha

et al. 2021

J Food Process Preserv

“…According to Santos, Barros, Monteiro et al. (2019), Bi is a dimensional number that correlates the rate of heat transport by conduction or mass by internal diffusion with the rate of heat or mass transport by external convection, being able to indicate the internal resistance of the product to the transfer process of heat and mass. Low values of Biot ( Bi ) number (1.00 × 10 −3 to 1.75 × 10 −3 ) were obtained under different conditions, which indicates that the internal resistance to mass transport is negligible (Ferreira et al., 2021).…”

Section: Resultsmentioning

confidence: 99%

Foaming characteristics and impact of ethanol pretreatment in drying behavior and physical characteristics for avocado pulp powder obtained by foam mat drying

Journal of Food Science

Almeida

Medeiros

et al. 2022

The objective of this study was to optimize the production of powdered avocado using foam mat drying. In order to achieve this, the effect of Emustab® (4, 6, and 8% w/w), goat's milk (10, 15, and 20% w/w), and whipping time (15, 20, and 25 min) on the foam physical properties of avocado pulp were evaluated. In addition, the influence of ethanol pretreatment on the drying kinetics, thermodynamic properties, and physicochemical characteristics of the powders was also assessed. An experimental design 23 with three central points was used in this study and optimized foam conditions were dried at 50, 60, and 70°C, with a fixed air speed of 1.5 m/s. Empirical and diffusive models (boundary conditions of the third type) were adjusted to the experimental data to describe the drying kinetics and to determine the process activation energy and thermodynamic properties. The final products were characterized regarding their physical properties. Optimized foam mat drying conditions were achieved when avocado pulp was whipped for 15 min and 8% of Emustab® and 20% of powdered goat milk were used as foaming agents. The use of an ethanol pretreatment and higher drying temperature (70°C) resulted in higher drying rate (1.6 × 102/min) and shorter processing time (270 min). The ethanol pretreatment reduced the activation energy and Biot number and led to more uniform moisture distribution. The physical properties, such as water content, water activity, bulk, and tapped densities decreased with an increase in drying temperature and pretreatment with ethanol, whereas water absorption capacity increased. Practical Application In this work, new information about the drying kinetics and mass transfer of the foam mat avocado pulp using ethanol as pretreatment is obtained. The results will contribute to the optimization production avocado foaming and powder. Ethanol pretreatment can represent an alternative to minimize the negative impacts on drying process and can be surely suggested as an industrial application.

“…This fit of the simulated model to the experimental data showed statistical indicators, such as the coefficient of determination ( R 2 ) close to 1 ( R 2 = 0.9995) and chi‐square function (

χ^{2}

) with a value of 0.61807. According to Silva et al (2019) and Santos et al (2019a), for a model to fit the experimental data, it is essential that, in addition to R 2 being greater than 0.99, the chi‐square value should be as low as possible.…”

Section: Resultsmentioning

confidence: 99%

Determination of thermal properties (and their uncertainties) during the cooling of apples (Malus communis)

J Food Process Engineering

Silva

Gomes

et al. 2022

The present study goal was to determine the thermal properties of apples during their cooling. Fuji apple was cooled in a domestic refrigerator by natural convection. Thermal properties were determined assuming the geometry of an equivalent sphere. An optimizer software (LS Optimizer) was used for the inverse problem. A new heat conduction software was developed to solve the direct problem, using the spherical geometry of the diffusion equation with the boundary condition of the third kind. Thus, thermal properties of apples and their uncertainties were calculated during cooling. The developed software for the direct problem was used to simulate the cooling kinetics for any previously specified point within the sphere. The fitting of the simulated curve to the experimental points showed coefficient of determination (R2) greater than 0.99 and low values of the chi‐square function (χ2). Therefore, it can be concluded that the spherical geometry and the boundary condition of the third kind were adequate to describe the process of heat removal for apple. Determined values of thermal diffusivity and convective heat transfer coefficient were α = (1.38 ± 0.07) × 10−7 m2 s−1 and h = (1.360 ± 0.018) × 10−6 m s−1, respectively, with confidence intervals of 95.4%. Another confirmation of the developed model was the fact that the thermal diffusivity was similar to the estimate by Riedel correlation (α = 1.38 × 10−7 m2 s−1). The position of the thermocouple in the equivalent sphere calculated by numerical solution was r = 6.6 mm. Practical Applications One of the main contributions of this paper is the calculation of thermal parameters along cooling with their uncertainties. This will result in very accurate simulation of the pasteurization and freezing processes. Furthermore, the values obtained in the study can be used to predict new cooling curves for the same product, but with different dimensions.