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.

Enhancing phytochemical parameters in broccoli through vacuum impregnation and their prediction with comparative ANN and RSM models.

Amidst increasing demand for nutritious foods, the quest for effective methods to enhance health-promoting attributes has intensified. Vacuum impregnation (VI) is a promising technique to augment produce properties while minimizing impacts on biochemical attributes. In light of broccoli's growing popularity driven by its nutritional benefits, this study explores the impact of VI using ascorbic acid and calcium chloride as impregnation agents on enhancing its phytochemical properties. Response surface methodology (RSM) was used for optimization of the vacuum impregnation process with Vacuum pressure (0.6, 0.4, 0.2 bar), vacuum time (3, 7, 11 min), restoration time (5, 10, 15 min), and concentrations (0.5, 1.0, 1.5%) as independent parameters. The influence of these process parameters on six targeted responses viz. total phenolic content (TPC), total flavonoid content (TFC), ascorbic acid content (AAC), total chlorophyll content (TCC), free radical scavenging activity (FRSA), and carotenoid content (CC) were analysed. Levenberg-Marquardt back propagated neural network (LMB-ANN) was used to model the impregnation process. Multiple response optimization of the vacuum impregnation process indicated an optimum condition of 0.2 bar vacuum pressure, 11 min of vacuum time, 12 min of restoration time, and 1.5% concentration of solution for vacuum impregnation of broccoli. The values of TPC, TFC, AAC, TCC, FRSA, and CC obtained at optimized conditions were 291.20 mg GAE/100 g, 11.29 mg QE/100 g, 350.81 mg/100 g, 1.21 mg/100 g, 79.77 mg, and 8.51 mg, respectively. The prediction models obtained through ANN was found suitable for predicting the responses with less standard errors and higher R2 value as compared to RSM models. Instrumental characterization (FTIR, XRD and SEM analysis) of untreated and treated samples were done to see the effect of impregnation on microstructural and morphological changes in broccoli. The results showed enhancement in the TPC, TFC, AAC, TCC, FRSA, and CC values of broccoli florets with impregnation. The FTIR and XRD analysis also supported the results.

Spotting of Volatile Signatures through GC-MS Analysis of Bacterial and Fungal Infections in Stored Potatoes (Solanum tuberosum L.).

Potatoes inoculated with Pectobacterium carotovorum spp., Aspergillus flavus and Aspergillus niger, along with healthy (control) samples, were stored at different storage temperatures (4 ± 1 °C, 8 ± 1 °C, 25 ± 1 °C) for three weeks. Volatile organic compounds (VOCs) were mapped using the headspace gas analysis through solid phase micro extraction-gas chromatography-mass spectroscopy every week. The VOC data were arranged into different groups and classified using principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) models. Based on a variable importance in projection (VIP) score > 2 and the heat map, prominent VOCs were identified as 1-butanol and 1-hexanol, which can act as biomarkers for Pectobacter related bacterial spoilage during storage of potatoes in different conditions. Meanwhile, hexadecanoic acid and acetic acid were signature VOCs for A. flavus, and hexadecane, undecane, tetracosane, octadecanoic acid, tridecene and undecene were associated with A. niger. The PLS-DA model performed better at classifying the VOCs of the three different species of infection and the control sample compared to PCA, with high values of R2 (96-99%) and Q2 (0.18-0.65). The model was also found to be reliable for predictability during random permutation test-based validation. This approach can be adopted for fast and accurate diagnosis of pathogenic invasion of potatoes during storage.

Understanding the variations in dielectric properties of mustard (Brassica nigra L.) and argemone (Argemone mexicana) oil blends at different temperatures.

Mustard oil is the most commonly adulterated edible oil, invariably with argemone oil. This study was aimed to develop a parallel plate capacitive sensor for measurement of dielectric properties of pure mustard oil, pure argemone oil and their blends (25, 50 and 75%) at five levels of varying temperature (10 to 50 °C). The effect of blend ratio and temperature on the selected dielectric properties of oil-capacitance (C), dielectric loss tangent (tanδ), dielectric constant ( ε ' ), dielectric loss factor ( ε ″ ) and electrical conductivity (σ) were investigated. It was observed that composition of the individual oils in terms of moisture and fatty acids influenced the physical and dielectric properties. The sensor was used to relate the dielectric properties of oil samples with blend ratio and temperature by means of statistically significant (p < 0.05) and robust (R 2 > 0.8) multiple linear regression model. The effect of temperature on C and ε ' was negative, while it was otherwise for tanδ, ε ″ and σ. Increase in argemone oil content in the blends, increased the dielectric measures due to the associated changes in the physical and chemical properties. The capacitive sensor could distinctly identify mustard oil, argemone oil and its blends on the basis of dielectric properties.

Mass transfer dynamics of simultaneous water gain and solid loss during soaking of pigeon pea grains.

Pigeon pea is the most prominently used protein source for human consumption. This is one of the leading pulse utilized in various applications in food processing. Soaking is one of the mandatory unit operation required to convert it from raw to a consumable form. Insights into its mass transfer dynamics enable the design and optimization of processing conditions with due consideration of retention of its quality and nutrition. In the present investigation, the mass transfer dynamics of simultaneous water gain and solid loss taking place during soaking was studied . The experimental samples were soaked at 35, 50, 75, 85, and 100 °C to represent the lower and upper gelatinization temperatures. The water diffusivities varied from 5.492 × 10-10 to 13.84 × 10-10 m²/s when soaking temperature was increased from 35 to 100 °C. Similarly, solid diffusivities vary between 6.27 × 10-10 at 35 °C and 9.48 × 10-10 m²/s at 100 °C. The activation energies of both the phenomenon were estimated using the Arrhenius equation. The mass transfer process has been identified with three distinct stages. The first stage was characterized by void filling, expansion, and solid hydration. The second stage was marked at 5% of solid loss and characterized by solid loss, while the third stage contributed to the starch gelatinization process. Simultaneous water gain and solid loss in the grain was observed throughout the process at varying rates. The insights into mass transfers from this study can help in further modeling of pigeon pea soaking behavior. PRACTICAL APPLICATION: Soaking is one of the mandatory step for further utilization of legume grains. Various desirable and undesirable changes take place during the soaking process. Pigeon pea being a leading legume, understanding of the dynamics of various chemical, physical, and compositional changes during soaking is very much required for a process design. Also the representation of these behaviors in mathematical models is essential to further understand and optimize the operations for maximum retention of quality attributes, minimum wastage, and low-energy consumption.

Effluent free infrared radiation assisted dry-peeling of ginger rhizome: A feasibility and quality attributes.

Infrared radiation (IR)-assisted peeling is one of the effulent free, environtment friendly emerging technique for tender fruit and vegetables. In this study standerdization and optimization of the infrared assisted dry-peeling method was carried out for ginger rhizome. During the investigation, the effects of selected independent parameters like infrared temperature (300-400 °C), heater to product surface spacing (10-30 mm), and treatment time (120-300 s) were studied on the peeling feasibility and quality as dependent variables. The experimental conditions were designed through CCRD statistical method. Multiple response optimization was done through RSM. The optimum conditions of selected independent variables were 300 °C IR temperature, 21 mm heater to product spacing, and 120 seconds treatment time resulted in the 90.40% of peeling efficiency, 35 °C of rhizome surface temperature, 8.67% of color change, 0.56% volatile oil loss, and 11.53 kg of firmness. The comparison of optimized infrared assisted peeling was carried out with conventional abrasion and lye peeling methods based on their quality attributes. IR assisted dry-peeling results in minimum quality losses, higher peeling efficiency and feasible over conventional peeling methods of ginger rhizome. There was zero effluent generated during infrared assisted peeling of ginger rhizome. PRACTICAL APPLICATION: Peeling is one of the foremost mandatory unit operation for processing of all fruits, vegetables, and rhizomes like ginger. Presently, lye peeling is most widely used peeling method in industries followed by mechanical peeling. Both of these methods have serious issues like huge effluent generation (BOD) and water consumption which leads to the concern about environmental issues. Infrared dry peeling is the most prominent alternative for industries having the potential to deals with environmental issues. IR peeling method can be easily designed and scaled-up as per the specific requirment of industries. Therefore, understanding its feasibility for peeling of a most difficult commodity like ginger and understanding its insight into the quality of peeled product is need of the hour.