Comparative analysis of optimized physiochemical parameters of dried potato flakes obtained by refractive and convective drying techniques

Enhancing physicochemical properties of papaya through osmotic dehydration with various natural sweeteners

Osmotic processes play a crucial role in developing high-quality intermediate moisture food products. This study investigates the role of osmotic dehydration focusing on using natural sweeteners to reduce health risks from refined sugar. Jaggery and honey were used for osmosis of papaya cubes, with a Box-Behnken design to determine optimal conditions: osmosis temperature (30, 40, 50 °C), osmotic solution concentration (40, 50, 60°Brix), and osmosis time (3, 4, 5 h). Simultaneous optimization of these parameters considered responses such as water loss, solid gain, weight reduction, colour change, ascorbic acid content, lycopene content, and phenolic content. The optimized conditions were identified as 49.46 °C, 40°Brix, and 5 h for jaggery osmosed samples and 39.64 °C, 60°Brix, and 4.92 h for honey osmosed samples. Drying the osmosed samples using advanced domestic solar dryer revealed superior quality (total phenolic content and lycopene content) in jaggery osmosed papaya compared to honey osmosed papaya. The study suggests that introducing a new osmotic agent, jaggery, can enhance the nutritional value of osmosed papaya cubes.

Optimization of process parameters of refractance window drying for aonla slices and comparison with other drying techniques

BACKROUND

Aonla is as a good source of antioxidants due to its high ascorbic acid and polyphenol contents. However, because of its high acidity and astringent taste, aonla is rarely consumed in its fresh form. As the constituents in aonla are heat sensitive, it is essential to find a suitable drying method for preservation. Therefore, refractance window drying (RWD) of aonla slices was studied as it has the potential of retaining heat-sensitive compounds.

RESULTS

The effect of RWD process variables, namely water temperature (75, 82.5, 90 °C) and slice thickness (2, 4, 6 mm), on different quality parameters of dehydrated aonla was studied. Increasing water temperature resulted in significantly higher ascorbic acid content, titratable acidity and product temperature, while total phenolic content, free radical scavenging activity and moisture content decreased. With the exception of product temperature, higher slice thickness led to an increase in the values of all the parameters. At the optimized processing conditions of 83 °C water temperature and 4 mm slice thickness, the ascorbic acid content, total phenolic content, free radical scavenging activity, titratable acidity and moisture content values were found to be 269.03 mg (100 g)-1, 242.33 mg (100 g)-1, 87.11%, 3.62% and 4% respectively. The aonla slices subjected to RWD also possessed 4-6% higher phytochemical content than osmotically dried and hot-air-dried samples.

CONCLUSION

This research highlights the effectiveness of RWD in preserving heat-sensitive compounds in food like aonla. The RW-dried slices had a smoother and more uniform microstructure compared to osmotically dried and hot-air-dried samples. © 2024 Society of Chemical Industry.

Modeling of moisture content during baking with different approaches for effective diffusivity and evaluation of quality variables in baked potato slices

Baking is a healthier alternative to frying, since texture, color, smell, and flavor are developed, without adding oil. The objective was to estimate the moisture content in potato slices, during baking using Fick's law of diffusion to model internal moisture transport and to assess the impact on quality attributes. Moisture transport kinetics were examined at three baking temperatures of 120, 130, and 140°C. Fick's law was employed to estimate average moisture content using different methods: considering both a constant (method of slopes by subperiods, MSS; and method of successive approximations, MSA) and a variable (represented as a quadratic function of time, QFT) behavior of effective diffusivity (De). Three quality variables were analyzed: water activity (aw, dew point hygrometry), total color difference (∆E, colorimetry), and fracturability (F, universal testing machine). The diffusivity estimated with the time-varying De method provided a more realistic description of moisture migration during baking. The aw, ∆E, and F for baked potato slices ranged from 0.234 to 0.276, 17.9 to 24.6, and 5.20 to 5.49 N, respectively. These attributes imply improved stability and extended shelf life, showing typical colors and texture changes for baked snacks. These changes are linked to variations in diffusivity, influenced by the size and quantity of micropores within the food structure. This study could allow an accurate prediction of mass transfer by considering variable De, facilitating the optimization of baking conditions. PRACTICAL APPLICATION: The analysis of the moisture content using Fick's law, considering a time-varying diffusivity, enables the optimization of the baking process for foods. This helps minimize the occurrence of defective products.

Development and standardization of processing technique for ready-to-use lab fermented Kanji mix using refractance window dried black carrot powder

Black carrots are rich in bio-actives but underutilized owing to their short-term availability and perishable nature. Traditionally, black carrots have been used for the preparation of Kanji-a fermented non-dairy beverage prepared using natural fermentation by lactic acid bacteria and a few spices. This plant-based probiotic beverage has high antioxidant properties but there is a risk of contamination with pathogens due to uncontrolled fermentation during storage. To enhance the availability of this nutritious beverage throughout the year and to ensure the microbiological safety of the traditional fermented product, the present study was planned to optimize the process for controlled fermentation using freeze-dried lactic acid bacterial (LAB) culture and refractance window-dried black carrot powder. The physicochemical and microbiological profiles of LAB-fermented Kanji were analysed. The dried Kanji mix can be reconstituted into naturally fermented probiotic beverage with unique flavour and aroma along with ensured microbiological safety and enhanced commercial value.

Refractance window drying of food and biological materials: Status on mechanisms, diffusion modelling and hybrid drying approach

Refractance window (RW) dryer has an immense advantage in terms of final product quality (textural and color attributes, nutrient retention), energy consumption, and drying time over other conventional dryers. RW is a thin film drying system and a technologically evolving drying process. RW drying is an energy-efficient (re-circulation of water) short drying process as the drying of food materials occurs due to a combined mode of heat transfer conduction, radiation, and convection (hot air circulates over film). The high-quality dried product is obtained because the product temperature remains below 80 °C. RW dryer application is not only limited to drying food products, but it can also be further used for improving the gelling and emulsion properties, formation of leather and edible film, and can be used for handling high protein products, drying leafy vegetables or marine foods as this process does not change any functional properties. Due to these advantages over other drying techniques, RW drying has gained academic and industrial interest in recent years. The industrial application of this technology at large scale is becoming difficult due because of large surface area requirement for mass production. Researchers are trying to scale-up by combing this technology with others technology (Infrared, ultrasound, solar energy, and osmotic dehydration). RW dryer is now extending from the food sector to other sectors like pharmaceutical, cosmetic, pigment, edible film formation, and encapsulation. Majority of the reviews on RW drying focuses on the product quality aspects. This review paper aims to comprehend the RW drying system more mechanistically to understand better the principles, diffusion models explaining the transfer processes, and emerging novel hybrid drying approaches.