Optimal drying conditions for valorization of industrial apple pomace: Potential source of food bioactive compounds

Apple pomace contains a large amount of useful bioactive compounds that have wide application in the food industry. In this study the effect of drying temperature and pressure (high temperature 80 °C and low temperature 60 °C using a conventional oven and a combination of conventional plus vacuum drying oven) on the antioxidant capacity and phenolic compounds of apple pomace extract was investigated. For a combination of conventional and vacuum drying ovens, samples were first dried by a conventional oven to a moisture content of approximately 10% then vacuum dried to reach a final moisture content of 3–4%. After the drying processes, ethanolic extraction was performed and the amount of total polyphenol and the antioxidant capacity (FRAP) were evaluated to determine a best drying method. The drying curves were also determined. The drying temperature affects the duration of the drying, the rate of water loss, and the remaining amount of antioxidant compounds.

Synthesis of nano-TiO2 assisted by glycols and submitted to hydrothermal or conventional heat treatment with promising photocatalytic activity

TiO2 nanoparticles were successfully synthesized by the sol-gel method employing different glycols (ethylene glycol, diethylene glycol or polyethylene glycol 300), which were heat-treated in conventional oven or by hydrothermal via, obtaining photocatalysts with particle sizes and distinct crystalline structures. HRTEM analyses showed that the oxides submitted to hydrothermal treatment featured spherical morphology, being formed by partially aggregated particles with sizes varying between 2 and 5 nm. X-ray diffractograms and Raman spectroscopy confirm that anatase was predominant in all synthesized compounds, with presence of brookite phase for samples that received hydrothermal treatment or were synthesized in the presence of polyethylene glycol with heat treatment in conventional oven. The amount of brookite as well as the cell volume, deformation, network parameters and crystallinity were estimated by Rietveld refinement. The surface area and porosity of the materials were higher when the synthesis involved the use of hydrothermal treatment. These oxides are mesoporous with porosity between 14 and 31%. The oxide synthesized in the presence of ethylene glycol with hydrothermal thermal treatment (TiO2G1HT) exhibited the highest photocatalytic activity in terms of mineralization of azo-dye Ponceau 4R (C.I. 16255), under UV-Vis irradiation. This higher photocatalytic activity can be attributed to the formation of binary oxides composed by anatase and brookite and by its optimized morphological and electronic properties.

Effect of Drying Methods on Bioactive Compounds and Antioxidant Capacity in Grape Skin Residues from the New Hybrid Variety “BRS Magna”

The effects of the drying process using the conventional oven and freeze-drying on the thermogravimetric profile, proximate composition, color parameters, individual bioactive compounds, and antioxidant activity in the grape residue (skin) were evaluated. Twenty individual phenolic compounds were identified, where a variation in concentration was observed for flavonols, stilbenes, phenolic acids, flavonoids, procyanidins, and particularly anthocyanins (malvidin-3,5-di-O-glucoside of 253.2–536.9 mg/kg) due to the drying process. Drying in a conventional oven caused a decrease of 23% of the total polyphenols. The skin of the BRS magna grape has a high concentration of total phenolic content of 489.5–148.3 mg.GAE/100 g, total anthocyanin content of 124.9–260.1 mg.CE/100 g, and total flavonoid content of 12.7–26.0 mg.QE/100 g. The results of free radical scavenging activity (1.26–4.91 μg/mL, as EC50) and ferric reducing antioxidant power (82.93–184.10 μmol/g of skin as equivalent to Fe2SO4) indicate high antioxidant activity, independently of the drying process applied. It was concluded that, if the application is directed to anthocyanin compounds, the use of lyophilization is recommended. On the other hand, if the interest is in bioactive compounds that exert antioxidant activity, conventional oven-drying can be used.

Nutrient Degradation in Baked or Air-Fried Sweet Potato Chips

Objectives The project tested the hypothesis that baked sweet potato chips will retain nutrients and can be produced with lower fat than commercially prepared fried chips. Sweet potato is a staple food that is a good source of dietary fiber, copper, manganese, antioxidants, vitamins C, A, B6, and E and is low in calories and fat. Orange-fleshed sweet potato is a good source of beta-carotene, a vitamin A precursor. Due to its nutritional benefits, demand is increasing and a growing market has created a variety of sweet potato products. Beta-carotene is a heat, light, oxygen labile molecule that can be used as a marker for nutrient degradation when sweet potato is heat-processed. Most commercial sweet potato chips are fried in oil, which helps to lower the glycemic index, but may also lower the nutrient density in the higher calorie product. Our goal is to test newer methods for making baked sweet potato chips with commercially available air-fryers and compare the products to chips baked with conventional and convection ovens. Methods Sweet potato chips were prepared from fresh commercially purchased Covington sweet potatoes cut into 3 mm slices with a semi-automatic food slicer. The slices were lightly sprayed with a vegetable oil aerosol and cooked in air fryers for 15 min at 400°F (204°C), in convection ovens for 15 minutes at 415°F (213°C), and in conventional oven at 400°F for 20 minutes. Crispness was determined by a 3-point bending test. Results The fresh sweet potato contained 22% DM and the chips averaged 70% DM after cooking in air fryers, 60% DM after cooking in convection ovens, and 64% DM after cooking in conventional oven. Beta-carotene content was 24.2 ± 4.5 mg/100 g DM in the fresh sweet potato, and decreased to an average 7.6 ± 1.9 mg/100 g DM in the air-fried chips, 14.1 ± 4.1 mg/100 g DM in the chips cooked in the convection ovens, and 6 ± 1.7 mg/100 g DM in the conventional oven. The rheological test found the chips with greater beta-carotene retention from the convection oven to be less crisp and have less charring than chips made in the air fryer or in the conventional oven. Conclusions Air frying technology shows promise for making low-fat sweet potato chips but nutrient degradation may still be an issue that needs further research. Funding Sources NC Agricultural Foundation.

Effectiveness of Preparation Practices on the Inactivation of Salmonella enterica Serovar Enteritidis in Frozen Breaded Chicken Strips

ABSTRACT Over the past 15 years, multiple foodborne outbreaks have occurred in Canada due to the presence of Salmonella enterica in frozen breaded chicken products. These chicken products were raw and required cooking in conventional household ovens to inactivate any pathogens that they may have been harboring. During the course of food safety investigations associated with these outbreaks, many consumers reported using alternative household appliances such as air fryers to cook these products. The effectiveness of these appliances for the inactivation of pathogens in food is not known. Here, we compare the ability of a toaster oven, air fryer, deep fryer, and conventional oven to inactivate a cocktail of Salmonella Enteritidis in frozen breaded chicken strips. Deep frying was the most effective cooking method, demonstrating a median 7-log reduction; the conventional oven was next with a median 6-log reduction. Both the air fryer and toaster oven performed poorly, with respective median 4- and 3-log reductions. Overall, the results of this study suggest the revision of cooking instructions is required for the safe household use of toaster ovens and air fryers. HIGHLIGHTS

Comparative analysis of drying coffee beans using microwave and conventional oven

This article reports a comparative study of experimental results obtained during the drying of Castilla-variety coffee beans from Santander, Colombia. They were performed by two means: thermal and electromagnetic radiation. Twenty experiments were carried out, ten tests in a microwave cavity at 2,450 MHz-1,080W, and ten tests using a conventional electric oven with temperature controlled at 50±2oC. Experiments were made using samples of coffee beans with parchment, without parchment, and of the only-parchment. For each sample, dimensionless moisture ratio and diffusion coefficients were determined, according to the second law of Fick. We found that the diffusion coefficient of the samples dried in a microwave cavity was twenty-two times higher than the diffusion coefficient of samples dried with thermal radiation. Likewise, it was observed that samples in conventional oven showed a uniform temperature, in contrast with those heated by microwave radiation. Such results are useful for designing hybrid systems for drying coffee beans.