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Development of process protocol for the production of powder from stevia (stevia rebaudiana)
(Punjab Agricultural University, 2023) Kalsi, Baldev Singh; Sandhya
Stevia rebaudiana leaves, renowned for their natural sweetness, have gained prominence as a healthier alternative to artificial sweeteners. The present research explores various aspects of Stevia leaf processing such as drying, extraction, and grinding, with a vision of optimizing both quality and efficiency. The fresh stevia leaves were dried using different methods: sun drying, convective drying (30-80°C), microwave drying (180 to 900 W) and multistage/hybrid drying: convective pre drying at 50 °C until reaching moisture content of 0.18 g/g, 0.43 g/g and 1.50 on dry basis (db) and then microwave finishing drying at power levels of 360, 540, and 720 W. The Artificial Neural Network (ANN) exhibited a reasonably good fit across all drying conditions to predict drying kinetics, surpassing the maximum R2 range and minimum χ2 and RMSE from the mathematical model. The multistage drying done at 1.50g/g-540W achieved the lowest total color difference (ΔE) value i.e 1.97 compared to other methods, indicating minimal color alteration. Furthermore, ascorbic acid content showed maximum retention after multistage drying at conditions of 1.50g/g-540W (23.50 mg/100g), followed by 1.50g/g-720W (23.04 mg/100g). Further, the total phenolic content also showed excellent results, with multistage drying at 1.50g/g-720W yielding the highest value (58.88 mg GAE/g), followed by 1.50g/g-540W (58.26 mg GAE/g). Additionally, very high antioxidant activity (78.67 %) was retained at the multistage drying at 1.50g/g-540W. The multistage drying at 1.50g/g-540W was selected as best drying as it not only significantly reduced drying time but also preserved the quality and bioactive compounds of Stevia leaves. A lab scale ohmic heating setup was also developed for extracting stevioside and bioactive compounds from dried leaves. The optimization of the ohmic heating assisted-extraction was executed using response surface methodology with temperatures (40-70°C), time (5-15 min) and solvent/ leaf powder ratio (10:1-30:1 ml/g) as independent parameters. The optimized conditions observed were 51.02˚C for 10.297 minutes using Solvent/leaf powder ratio of 30:1 ml/g for maximum stevioside, total phenolic content and antioxidant activity with overall desirability of 0.91. The innovative ohmic heating extraction method proved highly efficient, achieving an approximately 50% higher extraction efficiency for natural compounds from Stevia leaves compared to conventional thermal extraction. Besides enhancing the yield of valuable components, the novel approach also reduces processing time. After considering both visual decolorization and the impact on important quality parameters, the extract decolorized with 1g of activated carbon per 100 ml of stevia extract was deemed the most optimal choice. To combat the hygroscopic nature of Stevia extract powder, inulin (10% w/v) was introduced as an encapsulating agent before the spray drying process. The resulting spray-dried powder displayed favorable characteristics, ensuring improved stability. Moreover, successful crystal formation of stevia powder was achieved using Erythritol. The developed process demonstrated economic viability. In conclusion, this comprehensive study resulted in a process protocol for development of powder from stevia leaves keeping in view consumer preferences.
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Development of paddy straw based bio-composite packaging material for fresh produce
(Punjab Agricultural University, 2023) Potdar, Pratik Pandit; Preetinder Kaur
The present study was undertaken to explore the possibility of developing bio-composite rigid packaging using agricultural residues as an alternative to plastic packaging present being used for fresh produce packaging. Traditional non-biodegradable packaging materials like PET, LDPE, and PP had raised environmental concerns, prompting exploration into biodegradable polymers sourced from agricultural waste. To improve the biodegradability and suitability for fresh produce packaging, paddy straw, an abundant agricultural residue was opted and its characteristics were improved through alkaline pulping before incorporation in the biopolymer matrix. The process parameters for alkaline treatment i.e. alkali concentration, temperature, and time were optimized using Response Surface Methodology (RSM) through the assessment of response parameters like pulp yield, pH, ash content, lignin content, tensile strength, and browning index. Bio-composite materials using paddy straw powder (PSP) and various matrix materials i.e. PVA, PLA, and PBAT were fabricated using casting and moulding techniques. The developed bio-composite materials were analyzed for various physical, morphological, mechanical, thermal and degradation properties. Storage stability of PSP-based bio-composite rigid packages was compared with commercially used PVC and EVOH packages by conducting trials for packaging and storage of white button mushrooms. The alkaline treatment of paddy straw under optimized parameters i.e. 14% alkali concentration at a temperature of 53°C for 240 minutes enhanced the removal of lignin and hemicellulose, accompanied by structural modifications to cellulose, thereby improving the surface characteristics, making paddy straw suitable for integration into bio-polymer matrices. A PSP concentration of 30% was found suitable for fabrication of bio-composites with all three matrices based upon the evaluated characteristics. White button mushroom packaged in PSP-PVA, PSP-PLA and PSP-PBAT packages exhibited better quality for 6, 8, 8 days as compared to 4 and 6 days in PVC and EVOH packages, respectively. However, PSP-PVA packages displayed higher moisture absorption and loss of structure with regards to PSP-PLA and PSP-PBAT packages during storage. In conclusion, PSP-PBAT and PSP-PLA rigid bio-composite packages may provide a suitable alternative to PVC/EVOH packages for packaging of fresh produce like white button mushroom.
Embargo
Optimization of microwave drying process for rice milling and stabilization of rice bran
(Punjab Agricultural University, 2023) Ozukum, Merenungla; Satish Kumar
Investigations were carried out on optimization of microwave drying process for rice milling (PR121) and stabilization of rice bran. Experiments were planned with Box- Behnken design with five process variables viz. microwave power levels (180, 300, and 450 W), air velocity (3, 5, and 7 m/s), exposure time (4, 8 and 12s), bed thickness (3, 4.5, and 6 cm) and moisture content (12, 14 and 16%, wb). The response variables were milling recovery (MR), head rice yield (HRY), broken percentage (BP), degree of milling (DOM), free fatty acids (FFAs), peroxide value (PV) and saponification value (SV). Most of drying occurred in falling rate period and the peak value of drying rate varied between 1.718 - 4.702%, db/min. Paddy temperature during microwave reached a peak value of 56.73- 118.90oC. Average effective moisture diffusivity (Deff) ranged between 0.1415 - 0.6580 10-9 m2/s. Page model was found to be best among nine models tested describing the drying kinetics of paddy. Optimum values of process variables for drying of paddy were found to be microwave power level: 297.61 W, air velocity: 4.77 m/s, exposure time: 8.01s, bed thickness: 4.26 cm, and moisture content: 14.26%, wb with overall desirability of 0.819. The, optimum values of milling fractions and rice quality were MR: 72.06, HRY: 56.58, BP: 15.06, DOM: 7.71, FFA: 2.63%, PV: 3.44 meq/kg oil and SV: 181.39 mg KOH/g oil. At optimum conditions of microwave drying, MR and HRY increased by 3 and 6.73% respectively, DOM and lightness (L*) value of whitened rice reduced by 6 and 4% respectively; hardness (13%), cooking timing (4.41 min), water uptake ratio (19.24%), gruel solid loss (18%), cooked L/B ratio (4.2%), elongation ratio (3.44%) and overall colour difference (23.5%) were slightly higher than hot air drying. Further, thermal, and drying efficiency was higher by 67.43 and 92.95% respectively, but specific energy consumption decreased by 48.67% compared to hot air drying. Microstructure of starch granules treated with microwave showed more aggregated starch matrix and smooth surface structure than hot air drying. Further, the storage stability of rice bran from optimized microwave heating was extended to 60 days in vacuum packed refrigerated stored bran compared to 30 days in traditional (control).
Embargo
Development of protocol for postharvest quality management of stored mung bean using microwave and ozone
(Punjab Agricultural University, 2023) Kulwinder Kaur; Satish Kumar
The study aimed to optimize process parameters for ozone gas and microwave energy pre-treatment to maximize the mortality of C. maculatus (also known as pulse beetle) while minimizing the adverse effects on grain quality. Response surface methodology (RSM) was used, employing a Box-Behnken design (3x3) for ozone gas treatment and a full factorial design (2x3) for intermittent microwave heating. The optimized conditions for ozone gas treatment were moisture content: 11.28 %, ozone concentration: 939.98 ppm and exposure time: 2 h. For intermittent microwave heating, the optimal conditions were moisture content: 11.60 %, microwave power level: 435 W at a constant exposure time: 48 s, bed thickness: 4.5 cm, and air velocity: 3 m/s. These optimized conditions resulted in maximum mortality of all stages of C. maculates along with improved grain quality parameters. A grain recirculatory type ozone gas-based fumigation system was designed using Solid Works CAD software. The system showed a saturation time of 21.77 min, a saturated concentration of 1836.96 µg/L, an estimated half-life period of ozone as 10.35 min, and specific energy consumption of 524.62 kJ/kg. The proximate and mineral analysis of mung bean treated in the developed system showed a significant (p<0.05) decrease in protein, fat, and mineral content compared to the untreated samples but it varied non-significantly (p>0.05) vis-à-vis microwave treatment. Fourier Transform Infrared Spectroscope and Scanning Electron Microscope micrographs further confirmed molecular and structural modification in treated mung bean leading to reduced cooking time and enhanced functional, thermal, and pasting properties. The relationship between equilibrium moisture content and water activity predicted storage conditions as safe moisture content at aw 0.6: 11.80- 12.64 %, db and 7.87-13.43 %, db for ozone and microwave-treated mung bean respectively. The storage behavior of treated samples was studied over a 12-months using different packaging materials at retail and bulk levels. Variation in moisture content, headspace CO2 gas, and cumulative weight loss remained within safe limits while phytic acid content, total flavonoid content and antioxidant activity decreased with an increase in storage period with slight variation under high barrier films. Germination percentage was much higher than the Indian minimum Seed Certification Standards and was above 80 % for all treated samples. Ozone and microwave- treated mungbean grains packed in metalized laminated polymer (MLP) or cast polypropylene (CPP) bags at the retail level exhibited the longest shelf life of more than 12 months with acceptable quality, while LDPE (400-gauge) was found suitable for bulk packaging. Techno-economic analysis showed storage of treated and suitably packed grains has the potential to ensure long-term financial stability with an average payback period of less than one year.
Embargo
Development of process protocol for packaging and storage of groundnut kernels
(Punjab Agricultural University, Ludhiana, 2022) Gurjeet Kaur; Sidhu, Gagandeep Kaur
The spring grown groundnuts are prone to quality deterioration owing to high temperature and relative humidity during the harvesting. The present work investigated the impact of treatments and packaging systems on quality of groundnut kernels during storage. Spring varieties J87 and TG37A developed by Punjab Agricultural University were selected for the study. The fresh groundnut pods were dried using solar hybrid dryer at 60°C till the moisture content below 10% was achieved. Sample was decorticated and clean and healthy kernels were selected for the study. The sorption isotherms were developed at 25, 35 and 45°C temperature and water activity (aw) range of 0.110-0.975 in order to predict the suitable storage conditions. The equilibrium moisture content increased with increase in aw and the isotherms of type II were observed. The experimental data was fitted to seven mathematical models and Guggenheim Anderson de Boer and Double Log Polynomial were considered to be best fitted models. The safe storage conditions determined from best fitted models indicated that moisture content of J87 and TG37A varieties should not exceed 7.70 and 9.86 % (db) respectively during storage. The samples were subjected to three treatments viz. dry roasting (166 °C for 7 min), ozonation treatment (6 mg/L for 30 min) and combined ozonation-roasting (ozonation at 6 mg/L for 30 min followed by dry roasting at 166 °C for 7 min). The groundnut kernels were packed in low-density polyethylene (L), aluminum lined LDPE Ziplock bags (S) and aluminum laminate bags under nitrogen flushing (N) and in high barrier 5-layer polymeric laminate (PE/adhesive/EVOH/adhesive/PE) under vacuum packaging techniques. The samples were kept under ambient conditions for 12 months of storage period. Samples were analyzed for different quality parameters viz., moisture content, color characteristics, fracturability, radical scavenging activity, flavonoid content, protein, free fatty acids and aflatoxin content. Results indicated that treatments led to significantly (p<0.05) affect all the quality parameters except the hue angle and free fatty acids of J87 kernels and hue angle and chroma of TG37A kernels. The aflatoxin content after treatments exhibited values that were below the FDA established limit (20 µg/kg) for aflatoxins in groundnut kernels. The moisture content, chroma, total color difference, free fatty acids were found to be increased and hue angle, fracturability and protein content decreased with increase in storage period. FFA of groundnut kernels packaged in different materials were within acceptable limits (< 3%) for ozonated and ozonated-roasted samples. Radical scavenging activity and flavonoid content indicated a declined trend and then inclined as storage period approached 12 months. The maximum variation in quality parameters were observed in LDPE and zip lock bags. Vacuum and nitrogen flushed bags provided stable conditions with minimum alterations in quality of kernels. Microbial evaluation indicated dominance of Fusarium, Penicillium and Aspergillus spp. which was maximum in zip pouches followed by LDPE bags. It can be concluded that dried groundnut kernels with combined ozonation-roasting treatment, vacuum packaged in 5-layer modified polymeric laminate can be stored at ambient storage conditions for 12 months with maximum retention of quality parameters.
Open Access
Design, Development and Evaluation of Solar Hybrid Essential Oil Extraction System from Turmeric
(Punjab Agricultural University, Ludhiana, 2022) Tiwari, Ravindra Kumar; Mittal, T. C.
The present study was conducted to design and develop solar hybrid essential oil extraction system at Department of Processing and Food Engineering, PAU, Ludhiana. The conceptual design of the solar hybrid essential oil extraction system was done for essential oil extraction from turmeric. The system was designed in such a way that it will extract oil from a batch of about 10 kg of raw material. The volume of the distillation unit has a capacity of 0.061m3, the steam generation unit has a capacity of 0.057m3 and the condensing unit has a capacity of 40.50%. The smallest grates size (14.50mm) has the highest oil yield as compared to the largest grates size (17.53mm). The extracted essential oil was evaluated qualitatively in terms of refractive index, specific gravity color, saponification value, acid value, and ester values. The range of various chemical properties are specific gravity (0.89-0.93), refractive index (1.52-1.55), saponification value (35.21-38.13mg KOH/g), ester value (3.59-5.56mg KOH/g), acid values (31.61-32.59mg KOH/g) and colour values are L (32.70-38.90), a (-1 to -5.60) and b (10.6-19.40). The benefit-cost ratio was computed as 1.13 and break-even point for solar hybrid essential oil extraction system can be achieved after 1.85 years. The developed solar hybrid essential oil extraction reduces the extraction time (11.50%), energy consumption (11.75%) and can produce good quality essential oil which is free from wax. This environment friendly developed system lower operating and maintenance costs. The further analysis of the total extraction time and less energy consumption may help in designing a suitable solar hybrid essential oil extraction system with proper control of its operating parameters, and optimization of the process.
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Development of vacuum assisted osmotic impregnation system and CAS freezing technique for safe storage of guava (Psidium guajava)
(Punjab Agricultural University, Ludhiana, 2021) Afthab Saeed P.P; Alam, M. S.
A vacuum impregnation (VI) system for the improvement of nutritional characteristics of fresh and fresh-cut porous products and a cell alive system (CAS) freezing setup was designed and developed. The vacuum impregnation system was evaluated for the mass transfer kinetics and specific energy consumption with sucrose impregnated minimally processed guava (Psidium guajava). The VI process was optimized for guava slices using Box-Behnken design under response surface methodology to study the effects of vacuum pressure (50-150 mbar), solution concentration (40-60 oBrix), and solution temperature (40-60 oC) on water loss, solute gain, ascorbic acid content, titratable acidity, color change and firmness. The results obtained suggested that the mass transfer followed second order kinetics and the ratio of water loss to solid gain (WL/SG) attained a mass transfer equilibrium after a vacuum time of 20 min (Relaxation time = 15 min). The optimum VI conditions were observed for a sucrose concentration of 60 oBrix at the solution temperature of 40 oC under the vacuum pressure of 103 mbar at which the WL, SG, ascorbic acid, titratable acidity, color change, and firmness attained a value of 13.0%, 7.73%, 97.85 mg/100g, 0.36%, 5.36 and 1.51 N respectively. The effects of alternating magnetic fields on the freezing kinetics and quality parameters of minimally processed guava in the developed CAS setup were also investigated. The freezing process parameters including magnetic field intensity (2.4 – 8.8 mT) and cube size (2 – 4 cm) were optimized for guava cubes using the Response Surface Methodology technique. A comparative evaluation of freezing kinetics obtained for guava cubes frozen under different magnetic field intensities (2.4, 5.6, and 8.8 mT) was drawn with respect to the control samples. The two-factor, three-level Box and Behnken design suggested that the samples of size 4 cm, treated with a magnetic field intensity of 7.02 mT yielded the optimum freezing characteristics for which the values of phase change time, drip loss, and firmness were 77 min 35 s, 4.97%, and 1.34 N respectively. Under freezing process, the reduction in the phase transition time, in comparison with control samples, was maximum (62.42%) for 4 cm guava cubes at 8.8 mT, followed by 44.71% (3 cm cubes, 5.6 mT) and 27.36% (2 cm cubes, 8.8 mT), indicating the significant effect of guava cube size and higher magnetic field intensities on their freezing quality. The developed passing cooling chamber was effective in reducing the energy cost by 91.36 % (ice-cooled system) and 77.78% (brine-cooled system) in comparison to the refrigerated system. The osmotically pretreated guava cubes developed under optimized conditions i.e. 4 cm cube size, 103 mbar vacuum pressure, 40 oC solution temperature & 60 oBrix solution concentration followed by magnetic field assisted freezing at 7.02 mT for 75 min can be stored safely up to 9 days under passive cooling chamber (<4 oC) with acceptable quality attributes. Overall, the developed system and the process were found to be effective in retaining the quality and enhancing the shelf life of frozen guava cubes.
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Engineering characterization of selected cereal grain and legume crops for physical quality determination using machine vision technology
(Punjab Agricultural University, Ludhiana, 2021) Sharma, Rohit; Mahesh Kumar
A study was undertaken for the determining relevant engineering properties for physical quality estimation of selected wheat and green gram refractions using machine vision technology. The most common wheat varieties PBW 725 and Unnat PBW 343 and green gram varieties SML 832 and SML 668 were considered for the present study. The kernels were grouped into four categories such as sound grains, damaged grains, shriveled grains and broken grains for wheat. The type of grains for green gram include sound grains, shriveled grains, discolored grains and broken grains. For image acquisition, Digital images of one hundred kernels of each selected refraction of wheat and green gram were acquired using the flatbed scanner model CanoScan 5600F with CCD 6-line color with white fluorescent light source. The computer programming language Python version 3.7 and OpenCV image processing library were used for analysis of the images. A total of 30 features related to size and shape (14 features), color (10 features) and texture (6 features) of the selected kernels. For each category of refractions, red (R), green (G), and blue (B) color densities were extracted. Algorithms have been developed for analysis of images of refraction. A linear relationship was obtained between actual and predicted lengths and widths of selected refractions. The experimental results for length of refractions were found non-significant in comparison to predicted value at 95% confidence interval with R2 in the range of 0.81–0.94. The comparison results for width for all refractions are found statistically non-significant at 95% confidence interval and R2 was in the range of 0.73–0.92 for wheat refractions of both selected varieties. The paired samples t-test results showed that all parameters determined with image processing method was not significantly (P>0.05) different from the same parameters measured with vernier caliper. Another linear relationship was found between individual kernel weight and projected area with R2 in the range of 0.51 to 0.92 and between the volume of refractions derived from measured dimensions and calculated from image with R2 in the range of 0.75 to 0.93 for both wheat varieties. Correlation behavior between different parameters were observed using pearson correlation matrix. It was observed that in all wheat and green gram refractions, the individual kernel weight was found correlated significantly with projected area, perimeter, major diameter, feret diameter arithmetic mean diameter, geometric mean diameter, surface area and volume of kernels.
Open Access
Mathematical modeling of osmo assisted freeze drying process for strawberries (Fragaria vesca)
(Punjab Agricultural University, Ludhiana, 2021) Sidhu, Jashandeep Singh; Gupta, . S.K.
The study entitled “Mathematical modeling of osmo assisted freeze drying process for strawberries (Fragaria vesca)” was undertaken to characterize the effect of process parameters; osmotic solution concentration (40-80 °Brix), solution to fruit ratio (4-8 STFR) and freeze drying temperature (-20 to -40°C) on drying kinetics and quality attributes. The treatments with -20°C freeze drying temperature required more time for drying as compared to -30 & -40°C (2to 4 hours) to reduce the moisture content from 87.2% wb to 4.2±0.1 % wb. The input parameters for osmo-freeze drying process for strawberry halves were optimized by „Multiple Response Optimization‟ technique with optimum operating conditions recorded as freeze drying time temperature: -40°C, osmotic solution concentration: 79.43° Brix and solution to fruit ratio (STFR): 6.61. Corresponding to these values, the value of responses was rehydration ratio: 7.150, shrinkage ratio: 0.627, colour change: 6.661, bulk density: 502.19 kg/m3, % vitamin-c retained: 71.846%, texture (hardness): 8.1871Kg-f, and overall acceptability: 83.431%. The best fit of experimental data for osmotic dehydration was observed in Penetration model followed by GEM model. The overall performance of the mathematical model developed in VISUAL BASIC-6.0 for prediction of freeze drying time for osmo-freeze drying was satisfactory (0.122-7.285 % error) and can be used for predicting the freeze drying time for osmo-freeze drying of strawberries. The osmo-freeze and freeze dried products packed in three types of packaging materials viz. high density polyethylene, laminate aluminium pouches & glass jars were kept under refrigerated and ambient storage conditions. Overall, it was concluded that osmo-freeze drying of strawberry halves at optimized conditions of 79.43°B osmotic solution, 6.61 solution to fruit ratio (STFR) and 40°C freeze drying temperature gave better quality product as compared to freeze drying and can be stored for 5 and 3 months in refrigerated and ambient conditions respectively.

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