Determination of Drying Characteristics, Rehydration Properties and Shrinkage Ratio of Convective Dried Melon Slice with Some Pretreatments

Effect of dipping pre-treatments and drying methods on Aronia melanocarpa quality

This study examined the impact of different dipping pre-treatments (PO: potassium carbonate-olive oil emulsion, HW: hot water) and drying methods (sun, oven, hot air, and freeze) on aronia berry quality. Freeze-drying showed the highest process yield (29.07%-29.43%), while sun-drying had the lowest (24.60%-25.74%). PO pre-treatment showed superior moisture and water activity reductions across all drying methods. Notably, it enhanced carotenoid levels (PO: 399.5, HW: 371.4 mg BCE/kg), antioxidant activity (PO: 9602.8, HW: 9403.3 mg TE/kg), total phenolics (PO: 38176.5, HW: 34804.0 mg GAE/kg) and flavonoids (PO: 6537.1, HW: 6141.5 mg CE/kg) during freeze-drying. Additionally, PO-treated samples exhibited superior rehydration properties, with a ratio of 293.32% and a 1.01 g/g capacity. On the other hand, HW pre-treatment increased ascorbic acid levels (PO: 377.0, HW: 391.7 mg/kg). The highest quality dried aronia berries are generally observed in PO-treated samples, especially in freeze drying, followed by hot-air, oven, and sun drying processes.

Integrating Image Analysis and Machine Learning for Moisture Prediction and Appearance Quality Evaluation: A Case Study of Kiwifruit Drying Pretreatment

The appearance of dried fruit clearly influences the consumer's perception of the quality of the product but is a subtle and nuanced characteristic that is difficult to quantitatively measure, especially online. This paper describes a method that combines several simple strategies to assess a suitable surrogate for the elusive quality using imaging, combined with multivariate statistics and machine learning. With such a convenient tool, this study also shows how one can vary the pretreatments and drying conditions to optimize the resultant product quality. Specifically, an image batch processing method was developed to extract color (hue, saturation, and value) and morphological (area, perimeter, and compactness) features. The accuracy of this method was verified using data from a case study experiment on the pretreatment of hot-air-dried kiwifruit slices. Based on the extracted image features, partial least squares and random forest models were developed to satisfactorily predict the moisture ratio (MR) during drying process. The MR of kiwifruit slices during drying could be accurately predicted from changes in appearance without using any weighing device. This study also explored determining the optimal drying strategy based on appearance quality using principal component analysis. Optimal drying was achieved at 60 °C with 4 mm thick slices under ultrasonic pretreatment. For the 70 °C, 6 mm sample groups, citric acid showed decent performance.

Alternative flours from pulp melons (Cucumis melo L.): Seasonality influence on physical, chemical, technological parameters, and utilization in bakery product

Fresh vegetables have high water content and low acidity, so drying can extend shelf life, allowing the obtaining of alternative flours for the development of new products. The study aimed to investigate the influence of the melon harvest and off-season on the chemical composition of melon (Cantaloupe, Charentais e Honey Dew) flours and the potential application in products. The flours were evaluated for granulometry, morphology, centesimal composition, lipid and mineral content, total phenolic compound (TPC), antioxidant activity, and technological properties. Cakes containing melon flour were produced to replace wheat flour (0, 25, and 50 %) and evaluated for proximate composition, microbiology, and sensory parameters. Flours were classified as fine-grained (MESH >16), except Charentais off-season (medium - MESH 8-16, and fine-grained - MESH >16), and all presented a rough surface and minimal cell wall ruptures. The harvest homogeneously influenced the humidity, as all the off-season flours showed higher levels [17-22 %] (p < 0.05) due to weather conditions. For TPC, Cantaloupe melon flours from the harvest (CFH) [208 mg/100 g] and off-season [877 mg/100 g] stood out (p < 0.05), and the latter showed greater antioxidant potential [328 μmol TE/g]. Palmitic, linoleic, and linolenic acid stood out in all flours, and potassium for minerals (63-78 %) in the harvest and off-season. The harvest and off-season specifically influenced the flour of each variety in swelling power, water solubility, oil absorption, and emulsifying capacity. For cakes with CFH, no thermotolerant coliforms and Escherichia coli were detected, and the mesophilic count was <1.0 CFU/g. The ash, protein, lipid, and fiber contents increased proportionally to melon flour addition (p < 0.05). Sensory acceptance was high for cakes containing 25 and 50 % of CFH [82.78 % and 82.53 %], and most consumers would likely buy the products (4.04 and 3.99) (p < 0.05). The study contributed to knowledge about the seasonality effect and demonstrated the potential use of melon flour in developing new products.

Qualitative, energy and environmental aspects of microwave drying of pre-treated apple slices

In the present research, response parameters such as specific energy consumption (SEC), thermal efficiency (TE), energy efficiency (EF), drying time (DT), greenhouse gas (GHG) emission (such as CO2 and NOx), and quality features (color variation and shrinkage) were modeled by response surface methodology (RSM) for apple slices dried in a microwave dryer under ultrasonication (30 ℃-10 min) and blanching (80 °C-2 min) pretreatments. Also, RSM was applied to optimize two independent parameters including microwave power and sample thickness in the levels 100, 200, and 300 W and 2, 4, and 6 mm, respectively. The results indicated the significant influence (P < 0.01) of the independent parameters on the response parameters. The vales of SEC, DT, GHG emission, shrinkage, and color difference were linearly decreased with the declining sample thickness and increasing microwave power, while the energy and thermal efficiencies were increased by a quadratic equation. The use of ultrasonication and blanching pretreatments decreased the SEC, GHG emissions, and DT; while improving the quality of the samples as compared to the non-treated slices. The optimization results showed the optimal drying times (31.55, 82.19, and 50.55 min), SEC (3.42, 10.07, and 4.37 MJ/kg), CO2 with natural gas (1539.75, 1518.75, and 4585 g), CO2 with gas oil (3662.53, 2099.25, 2721.25 g), NOx with natural gas (10.094, 9.956, and 12.906 g), and NOx with gas oil (12.934, 12.758, and 16.538 g) at a microwave power of 300 W and sample thickness of 2 mm with desirability of 0.921, 0.935, and 0.916 for control samples, ultrasonicated, and blanched, respectively.