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Effect of cold plasma treatment on quality parameters of spinach
(Punjab Agricultural University, 2023) Goswami, Kritanjal; Sandhya
Investigations were carried out to study was the effect of cold plasma treatment on spinach quality parameters. Design and development of a plasma setup with an adjustable top portion and strips for adjusting the discharge gap that operated at a 25.00 kHz frequency and a discharge voltage range of 32.00 kV to 47.00 kV. The treatment chamber was made of 8 mm thick glass, aluminum foil and pyrex glass were utilized as dielectric barriers, a switch-mode power supply (SMPS) was used to convert AC power to DC, a voltage controller was in charge of controlling the voltage output, and an EHT component serving as a transformer boosted the voltage. By altering exposure period, discharge gap, sample weight, and output voltage, independent variables were manipulated to optimize the cold plasma system, yielding a desirability value of 0.824. Optimal conditions included 20.00 g sample weight, 3.50 cm discharge gap, and 4.00 min exposure, resulting in desired outcomes: 92.39% moisture content, color value of 7.82, texture at 9.38N, chlorophyll content of 2.94 mg/g, total phenol content of 38.55 mg GAE/g, and microbial load of 2.79 log10 CFU/g. Cold plasma-treated and controlled spinach, stored in both ambient and refrigerated settings, packaged in PP and LDPE, showcases prolonged shelf life, improved moisture retention, color, texture, chlorophyll levels, microbial safety, and flavor preservation in comparison to control spinach. Cold plasma treatment effectively upholds spinach quality in PP packaging, elevating visual appeal, nutrition, and overall freshness for up to 3 days at ambient temperature and 9 days in refrigeration. An economic analysis, considering fixed and variable expenses, estimates a Rs. 57,200/- return over variable cost for the developed cold plasma system post-expenditure. It's important that this cutting-edge method showed little adverse effect on the sensory and nutritional qualities of fresh spinach while appreciably extending its shelf life.
Embargo
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.
Open Access
Effect of different precooling methods and storage conditions on shelf life and quality of pear (Pyrus pyrifolia (Burm. F) Nakai)
(Punjab Agricultural University, Ludhiana, 2022) Mahajan, Kashika; Gupta, S.K.
The present investigation entitled “Effect of different precooling methods and storage conditions on shelf life and quality of pear (Pyrus pyrifolia (Burm. F) Nakai)” was conducted during the year 2021-22. Three methods of pre-cooling i.e; hydrocooling (HC), forced air cooling (FAC) and evaporative cooling (EC) were evaluated for postharvest quality of pear fruit under cold storage and ambient storage conditions. Two experiments were laid out viz (i) Optimization of precooling time of pear fruits using different precooling methods and (ii) Effect of precooling methods on storage life and quality of pear fruit under cold storage and ambient conditions. In the first experiment the data exhibited that HC took 130 minutes and FAC took 360 minutes to precool the pear fruits from 34.9oC to 5.2oC. However, the EC could not achieve the desired temperature to precool the pear fruit. In the second experiment the fruit were subjected to HC, FAC and EC treatments for requisite time period as determined in first experiment. The fruits were packed in corrugated fibre board boxes and stored in cold room (0-1⁰C temp and 90-95% RH) and at ambient conditions (28-32oC and 70-80% RH). The stored samples were evaluated periodically for various physiological and biochemical parameters. The data revealed that FAC was found to be the best precooling method to enhance the shelf life of pear fruits upto 60 days under cold storage conditions and 15 days under ambient storage conditions. The control fruits maintained the storage life upto 45 days under cold storage and 10 days under ambient conditions.
Embargo
Effect of different packaging films on storage life of tomatoes in consumer packages
(Punjab Agricultural University, 2023) Pooja; Sharma, S. R.
The present investigation was conducted to evaluate the effect of different packaging films on storage life of tomatoes in consumer packages. Five packaging films HDPE (25μ), LDPE (25μ), PP (25μ), shrink (15μ) and cling (15μ) were used to wrap the consumer packages made of corrugated trays. These film wrapped consumer packages were evaluated for postharvest quality of tomato cv. Punjab Varkha Bahar 4 under ambient and cold storage conditions. The physico-chemical parameters measured to determine the storage life of tomato were PLW, spoilage, firmness, colour, gas concentration, TSS, titratable acidity, total phenols, ascorbic acid and lycopene content at 0, 3, 6, 9, 12 and 15 days of storage under ambient storage conditions (17.4-19 °C, 25-28% RH) and at 0, 7, 14, 21, 28 and 35 days of storage under cold storage conditions (10±1°C and 90-95% RH). Cold storage of tomato was found to be better than ambient storage. Tomato packed in cling film wrapped consumer packages were found to be best for 9 days of storage life with desirable physical and chemical attributes as compared to control packages which maintained the storage life up to 3 days only under ambient storage conditions. Tomatoes packed in cling film wrapped consumer packages proved to be the best for 21 days of storage life with minimum weight loss and spoilage, desirable fruit firmness, better colour and other quality parameters as compared to control packages which maintained the storage life up to 7 days only under cold storage conditions.
Restricted
Development of biodegradable packaging material from Groundnut shell
(Punjab Agricultural University, 2023) Sukhdeep Kaur; Sidhu, Gagandeep Kaur
The present study was conducted for the development of biodegradable film from groundnut shell. Different physico-chemical properties viz. moisture content, ash content, bulk density, true density, cellulose content, hemicelluloses content and lignin content were measured using standard methods. Experiments were conducted to investigate the effects of different process parameters viz. shaker time (6, 12 & 18h), shaker speed (160, 180 & 240rpm) and enzyme concentration (80, 100 & 120mg) on lignin content and drying time (10, 20 & 30h), drying temperature (50, 70 & 90◦C), dark or light condition (-1, 0 &1) on cellulose content, lignin content and moisture content on the composition of groundnut shell powder. The results of isolation of lignin from groundnut shell powder The optimization of process parameter was done using response surface methodology (RSM) design trial version 7 Box-Behnken Technique. The biodegradable film from groundnut shell powder was developed by solution casting method. The three types of films viz. agar powder based, mixture of agar powder and peanut shell powder and mixture of agar powder and cellulose microfiber was developed at optimized conditions. The different physico- mechanical properties of different types of films were measured. The maximum thickness was achieved by the cellulose microfiber-based film. The agar-based film had a minimum thickness of 0.18 mm. The transmittance value of agar film was lesser than that of CMF film and PSP. The CMF film's WS percentage decreased in comparison to that of the other two films. CMF film which is made with cellulose and agar, has a higher tensile strength than the other two films. CMF and PSP films had a higher opacity value than agar films. AG films show less weight loss, and when compared to PSP films, It was observed that PSP loses less weight than CMF film in the soil burial degradation test because lignin was present.
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
Vacuum-assisted osmotic pretreatment induced magnetic freezing of mushroom
(Punjab Agricultural University, 2022) Wagh, Muktabai Dinesh; Alam, M. S.
Mushroom, extremely perishable in nature having tendency to lose its quality after harvest with a limited shelf life needs a technique to convert it to a self-stable product. Keeping in view the above points, the technique has been developed and optimized/standardized for developing self-stable frozen button mushroom by using developed vacuum impregnation (VI) system and optimized its operational process parameters followed by Magnetic-field assisted freezing (MAF) for whole and sliced mushrooms. The VI process parameters selected were solution temperature (ST) (35-55 °C), salt concentration (SC) (4-12 %), vacuum pressure (VP) (50-170 mbar) and immersion time (IT) (30-90 min) with constant solution to sample ratio (4:1) and were optimized on the basis of maximum water loss (WL), solute gain (SG), ascorbic acid content (AA), titratable acidity (TA), firmness (F) and minimum color change (CC) and pH. In each experimental combinations, desired concentration i.e 1 percent Ascorbic acid and 1 percent Calcium lactate was mixed with the hypertonic salt solution for selected duration by applying desired vacuum for 15 min irrespective of the experimental immersion time followed by restoration at atmospheric pressure. In order to develop frozen mushroom (whole and sliced), the experiments were conducted using MAF setup developed in the department. The system was operated and evaluated using AC and DC supply i.e. alternating magnetic-field assisted freezing (AMAF) and static magnetic-field assisted freezing (SMAF) by varying the operational parameters i.e. intensity of magnetic field, forms of mushroom and type of sample (fresh and vacuum impregnated) and was compared with conventional freezing (control). The samples were evaluated for freezing kinetics (total freezing time, phase change time, freezing rate, freezing temperature and nucleation temperature) thawing loss and physico-chemical properties (AA, TA, F, CC and overall acceptability). The best frozen mushroom (fresh and vacuum impregnated) developed by DC supply was packed in different packaging material (plastic punnets and polypropylene bag) and stored in deep freezer (-22 ºC) and evaluated for its quality changes at regular interval. The optimum values of VI process parameters and responses obtained for whole mushroom were IT-75 min, ST-41°C, SC-10%, VP-140mbar and WL-22.14%, SG-2.31%, AA-28.74mg/100g, TA-0.28%, CC-4.61, F-9.85 N and pH-5.37 respectively with overall desirability of 0.85. The optimum values of VI process parameters and responses obtained for sliced mushroom were IT-60 min, ST-42°C, SC-9% and VP-140 mbar and WL-26.64%, SG-2.91%, AA-34.06 mg/100g, TA-0.35%, CC-4.34, F-6.28 and pH-5.23 respectively with overall desirability of 0.80. It can be concluded that the best frozen sample for MAF was observed at 10 mT under SMAF and the mushroom packed in plastic punnets retained significantly higher physical and nutritional qualities attributes. Overall, the VI system and MAF technique were found effective in maintaining the quality and enhancing the shelf-life of whole as well as sliced mushroom.
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.

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