Investigation of thermal performance, drying characteristics and environomical analysis: direct flow evacuated tube solar drying of okra.

A direct flow evacuated tube solar dryer (DF_ETSD), a novel drying system, was used for drying pre-treated okra (Abelmoschus esculentus). The performance of DF_ETSD was analysed by determining thermal profiling, dryer and collector efficiency hourly. The maximum 3-day average ambient temperature, collector outlet temperature and solar radiation were 35.6 °C, 66.4 °C and 976 W m-2 respectively. The collector efficiency increased as solar radiation increased over time due to a higher temperature difference between the collector outlet and ambient temperature. The maximum collector and dryer efficiency observed were 30.19% and 21.47%, respectively. A pre-treatment of okra was done in hot water at 70, 80 and 90 °C for 5 min. Okra samples were dried from an initial moisture content of 87.42 ± 1.49% (wb) to a final value of 10.77 ± 1.03% (wb) in 9 h. The pre-treatment temperature of 80 °C is suitable for maximum drying rate, colour retention and rehydration ratio and minimum water activity, which signifies the longer shelf-life of okra. Midilli and Kucuk model was best fitted (highest R2, lowest χ2 and RMSE) for the control and samples pre-treated at 80 °C; however, Verma model was suitably fitted for the sample pre-treated at 70 and 90 °C. The payback period of DF_ETSD was found to be 1.27 years. Environmental analysis shows the CO2 emission and net CO2 mitigation ranged between 1.24 and 18.65 t and 9.86 and 154.05 t respectively for different selected lifecycles of the dryer. Due to its environmental sustainability and low payback period, the presented drying system is recommended for okra and other fruits and vegetables.

Recent trends and applications of evacuated tube solar collector in food processing and air heating: a review.

Solar energy demand is growing for future energy needs in different sectors to replace fossil fuels, which leads to a reduced carbon footprint and global warming. Evacuated tube solar collectors (ETSC) harness solar thermal energy for air heating, water heating, and drying in domestic and industrial sectors. The review paper comprises ETSC technology categorization, influencing factors like fin arrangement, integration of phase change material, tilt angle, solar radiation, and airflow rate on the performance of ETSC-based solar air heaters and dryers. The thermal performance parameters, like the collector efficiency, dryer efficiency, energy and exergy efficiency, thermal profile, zone temperature, relative humidity, heat loss during operations, etc., are reviewed. The developed ETSC-based air heating systems and solar dryers for drying agricultural products are performed effectively. However, research progress on improving the thermal performance integrated with nanofluids and phase change materials was discussed. CO2 mitigation analysis and global standards for ETSC-based air heaters and dryers are compiled. A large scope exists by use of solar air heaters (SAH) for food commodity drying with a suitable drying chamber and improving the designs of ETSC-based solar dryers. The work accomplished by various researchers has been analyzed in this study for prospective research gaps in the context of future design and development.

Revolutionizing goat milk gels: A central composite design approach for synthesizing ascorbic acid-functionalized iron oxide nanoparticles decorated alginate-chitosan nanoparticles fortified smart gels.

Goat milk gels (GMGs) are popular food due to their high water content, low-calorie density, appealing taste, texture enhancers, stability, and satiety-enhancing characteristics, making them ideal for achieving food security and zero hunger. The GMGs were optimized using the central composite design matrix of response surface methodology using goat milk powder (35-55 g), whole milk powder (10-25 g), and potato powder (10-15 g) as independent variables. In contrast, complex modulus, flow stress, and forward extrudability were chosen as dependent variables. The maximum value of complex modulus 33670.9 N, good flow stress 7863.6 N, and good extrudability 65.32 N was achieved under optimal conditions. The optimized goat milk gel was fortified with ascorbic acid-coated iron oxide nanoparticle (magnetic nature) decorated alginate-chitosan nanoparticles (AA-MNP@CANPs), making it nutritionally rich in an economically feasible way-the decorated AA-MNP@CANPs characterized for size, shape, crystallinity, surface charge, and optical characteristics. Finally, the optimized fortified smart GMGs were further characterized via Scanning electron microscopy, Rheology, Texture profile analysis, Fourier transforms infrared (FTIR), and X-Ray Diffraction (XRD). The fortified smart GMGs carry more nutritional diversity, targeted iron delivery, and the fundamental sustainability development goal of food security.

Predictive Modeling of Riboflavin Production in Lactiplantibacillus plantarum MTCC 25432 Using Fuzzy Inference System.

Riboflavin (Vitamin B2) is an essential vitamin and a microbial metabolite produced by some lactic acid bacteria (LAB). This investigation aims to study the overproduction of riboflavin in selected Lactiplantibacillus plantarum strain by using the one factor at a time (OFAT) tool coupled with the Fuzzy Inference System (FIS) and its validation through fermentative production in semi-defined media. Out of three Lactiplantibacillus strains used in this study, the maximum riboflavin producing strain was selected based on its ability to grow and produce higher levels of riboflavin. In results, Lactiplantibacillus plantarum strain MTCC 25432 was able to produce 346 µg/L riboflavin in riboflavin deficient assay medium and was investigated further. By using the OFAT-fuzzy FIS system, casamino acid in the range of 5-20 g/L, GTP 0.01-0.04 g/L, sodium acetate 5-15 g/L, and glycine 5-15 g/L were used to predict their effect on riboflavin production. The conditions optimized with modeling showed a 24% increment in riboflavin production (429 µg/L) by Lactiplantibacillus plantarum MTCC 25432 vis-a-vis the unoptimized counterpart (346 µg/L). In conclusion, an FIS-based predictive model was effectively implemented to estimate the riboflavin within an acceptable limit of 3.4%. Riboflavin production enhancing effects observed with various levels of sodium acetate, casamino acid, and GTP could be useful to re-design matrices for riboflavin production.

Application of novel pretreatment technologies for intensification of drying performance and quality attributes of food commodities: a review.

Drying is an energy-intensive process that can be reduced by the application of pretreatment prior to drying to enhance mass transfer and minimize energy consumption. This review summarizes the mechanistic aspects and applications of emerging pretreatment approaches, namely ohmic heating (OH), ultrasound (US), high pressure processing (HPP), and pulsed electric field (PEF), with emphasis on the enhancement of mass transfer and quality attributes of foods. Novel pretreatments significantly improved the drying efficiency by increasing mass transfer, cavitation, and microchannel formation within the cell structure. Various processing parameters have great influence on the drying performance and quality attributes of foods. Several studies have shown that novel pretreatments (individual and combined) can significantly save energy while improving the overall drying performance and retaining the quality attributes. This work would be useful for understanding the mechanisms of novel pretreatment technologies and their applications for future commercial research and development activities.

Characterization of rice flour and pastes with different sweeteners for extrusion-based 3D food printing.

This work aims at investigating the impact of commonly used sweeteners-sugar and jaggery on 3D printability of rice flour (RF) paste. The physicochemical characteristics of rice flour suitable for 3D food printing have been investigated. Three mixes, rice flour with water (M1 : RF-50.86%, water-49.14%), rice flour with sugar and water (M2 : RF-36.75%, sugar-14.10%, water-49.14%) and rice flour with jaggery and water (M3 : RF-36.75%, jaggery-14.10%, water-49.14%) were compared on 3D printability based on visual inspection and properties supporting 3D printability and shape retention. The effect of the three mixes was characterized on color, rheological, thixotropic, and handling properties. Out of the three mixes, M3 is found to have the best printability characteristics with shear thinning behavior, yield stress of 157 Pa, flow stress of 121 Pa, and extrusion force of 6.62 kg.

Fatigue Life Assessment of 65Si7 Leaf Springs: A Comparative Study.

The experimental fatigue life prediction of leaf springs is a time consuming process. The engineers working in the field of leaf springs always face a challenge to formulate alternate methods of fatigue life assessment. The work presented in this paper provides alternate methods for fatigue life assessment of leaf springs. A 65Si7 light commercial vehicle leaf spring is chosen for this study. The experimental fatigue life and load rate are determined on a full scale leaf spring testing machine. Four alternate methods of fatigue life assessment have been depicted. Firstly by SAE spring design manual approach the fatigue test stroke is established and by the intersection of maximum and initial stress the fatigue life is predicted. The second method constitutes a graphical method based on modified Goodman's criteria. In the third method codes are written in FORTRAN for fatigue life assessment based on analytical technique. The fourth method consists of computer aided engineering tools. The CAD model of the leaf spring has been prepared in solid works and analyzed using ANSYS. Using CAE tools, ideal type of contact and meshing elements have been proposed. The method which provides fatigue life closer to experimental value and consumes less time is suggested.

Effect of Assembly Stresses on Fatigue Life of Symmetrical 65Si7 Leaf Springs.

The maximum stress induced plays vital role in fatigue life improvement of leaf springs. To reduce this maximum stress, leaves with different unassembled cambers are assembled by pulling against each other and a common curvature is established. This causes stress concentration or sets assembly stress in the assembled leaf springs which is subtractive from load stress in master leaf while it is additive to load stress for short leaves. By suitable combination of assembly stresses and stepping, it is possible to distribute the stress and improve the fatigue life of the leaf spring. The effect of assembly stresses on fatigue life of the leaf spring of a light commercial vehicle (LCV) has been studied. A proper combination of stepping and camber has been proposed by taking the design parameters into consideration, so that the stress in the leaves does not exceed maximum design stress. The theoretical fatigue life of the leaf springs with and without considering the assembly stresses is determined and compared with experimental life. The numbers of specimens are manufactured with proposed parameters and tested for load rate, fatigue life on a full scale leaf springs testing machine. The effect of stress range, maximum stress, and initial stress is also discussed.