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ThesisItem Open Access PULSED ELECTRIC FIELD, MICROWAVE AND ULTRASONICATION ASSISTED EXTRACTION OF PHOSPHOLIPIDS FROM GHEE RESIDUE(ICAR-SRS-NDRI, KARNAL, 2023) RAJESH. K; MENON REKHA RAVINDRAGhee residue is the dark brown sediment obtained as a by-product during the heat clarification of butter or cream. It is often discarded as waste, causing environmental concern, or used as animal feed by most ghee manufacturing dairy plants. It is found to be good source of lipids including phospholipids (PLs), which is reported to have good emulsifying property. The present study is an attempt to obtain a PLs enriched extract from ghee residue using assisted extraction techniques such as microwave (MW), ultrasound (UL) and pulsed electric field (PEF). The PLs in ghee residue was enriched to 9.56% from 4.98% through series of pre-treatments viz., hydraulic pressing, boiling water treatment and comminution to 0.25 mm particle size. This pre-treated ghee residue was subjected to the assisted extraction process with different solvents like water, ethanol and enzyme treatment and water as solvent was deduced to yield better yield of PLs in the extract. Taguchi orthogonal design T9 was used to optimize process parameters for the three assisted extraction techniques based on yield of PLs and antioxidant activity of extract. Extraction at optimized combination of power (540 W), time (60 s), solvent to solid ratio of 10 (S:S-v/w) resulted in a yield of 21.96% PLs in the microwave treated extract. Ultrasound assisted extraction was optimized at power (80%), time (4 min.) solvent temperature (80oC) and S:S ratio 15 and reported a yield of 24.12% PLs in the extract. PEF treatment reported PLs yield of 18.14% at optimal levels of voltage (60 kV/cm), time (5 min.) and S:S ratio of 7.5. The antioxidant activity of the extracts obtained by microwave, ultrasound and PEF assisted techniques was found to be 29.89, 51.94 and 37.01% radical scavenging activity for extract, respectively, when determined at the optimal process conditions for maximising the activity. The extract was evaluated for the classes and species of PLs present by LC- MS and results indicated presence of 61, 118 and 31 species across 5 classes of PLs in the extract obtained by MW, UL and PEF assisted process, respectively. Kinetics of extraction in the MW assisted technique followed Peleg’s model whereas, ultrasound and PEF assisted extraction process was best described by the parabolic model. Evaluation of the extract from ghee residue exhibited good emulsion capacity and stability at concentration of 5% for extract obtained with MW and UL assistance, while a concentration of 10% was required for similar results for extract obtained with PEF assistance. Analysis of hydrophilic-lipophilic balance (HLB) of extract from all three assisted techniques deduced the values to be close to 10. Replacement of guar gum and glyceryl monostearate in different proportion with the extract obtained with MW and UL assistance in ice cream mix resulted in comparable attributes for textural, fat destabilization, overrun and melting properties of ice cream mix and hardened ice cream, to the respective control sample. The study demonstrated the efficacy of obtaining a PLs rich extract from ghee residue using assisted extraction techniques and the scope of utilizing the extract as replacement for conventional emulsifier in dairy products such as ice cream.ThesisItem Open Access DESIGN AND DEVELOPMENT OF PHASE CHANGE MATERIAL BASED MILKING CUM COOLING PAIL(ICAR-SRS-NDRI, KARNAL, 2022) RAVI PRAKASH; MENON REKHA RAVINDRAIt is essential to immediately chill fresh raw milk from its milking temperature (37°C) to below the critical point (10°C) to preserve its safety and quality as well as derived products. In developed and large-scale commercial dairy enterprise, this critical step in post-harvest processing of milk is achieved by integrating the milking machine with chilling unit accessorized with suitable piping and storage tanks. However, in a country like India where most of the dairy farmers belong to a class of millions of scattered small scale producers (0.5-10L per head), such sophistication remain impractical and uneconomical at the field level. Hence, this project was aimed at addressing the issue by developing a nano-particle enhanced phase change material (NePCM) based milking cum cooling pail, so that cooling as well as milking can be achieved simultaneously, even if the farmer has only one animal. NePCMs were developed by dispersing nano-particles (TiO2, CeO2 and Si3N4) into different base-fluids viz., distilled water (DW), distilled water+propylene glycol (DW+PG), distilled water+ethylene glycol (DW+EG) and distilled water+silver nano-ionic solution (DW+AgNP) @ 0.00, 0.05, 0.25, 0.50, 0.75 and 1.00%. The NePCMs were characterized for thermal, nano-structural and milk cooling behaviour in the milking pail. Prior to fabrication, the charging and discharging of NePCMs into the pail were simulated in ANSYS-fluent-19 software. Finally, a milking pail made of SS-304 assimilating the developed NePCM was fabricated and coupled with a matching capacity charger to pre-store the thermal energy prior to milking. The units were tested in lab as well as at farm (LRC of SRS, ICAR-NDRI, Bengaluru). The maximum enhancement of ‘thermal conductivity (k)’ of NePCM was observed using TiO2 nanoparticles at 1.00% weight fraction, between 30-40°C, in DW+AgNP base fluid. Milk cooling as well as discharging of NePCM were influenced by nanoparticle concentration and agitator speed. The total energy exchange time for milk cooling was accelerated by 8.00, 18.67, 25.33 and 30.67%, respectively at 30, 50, 70 and 100 rpm, as compared to control (0 rpm) at 1.00% of TiO2 nanoparticles in NePCM. Experimental validations of the simulated results indicated a close agreement confirming the robustness of the simulation. Thus, a milking cum cooling pail based on developed PCM was successfully designed, fabricated and tested to cool milk from 37 to below 10°C in 30-40 min. The PCM in the developed pail maintained the chilled temperature of the raw milk for at least 4h when exposed to an environmental temperature of 40°C. The PCM formulated with enhanced thermal performances assimilated into the pail efficiently cooled fresh raw milk from the point of production to below the critical temperature, which could help preserve the quality of the raw milk in the primary tier of the supply chain.ThesisItem Open Access DESIGN AND DEVELOPMENT OF MECHANICAL UNIT FOR DRY CRYSTALLIZATION OF PALADA PAYASAM MIX(ICAR-SRS, BENGALURU, 2019) DESHMUKH, GAJANAN P; RAVINDRA, MENON REKHAA mechanical unit working on the principle of Scraped Surface Heat Exchanger was developed for the dry-crystallization of the Palada payasam mix. The unit was designed as a flat-bottom cylindrical steam jacketed kettle with a custom-designed scrapper assembly. The mechanical drive for scrapper assembly in the form of a top driven gear box attached induction motor and a process control panel were suitably designed and assembled. The scrapper assembly consisted of Teflon reinforced SS scraper blades and comb type scrapers blades attached alternatively at angular distance of 90o each to achieve desired scrapping cum mixing effect. The process parameters for the dry-crystallization process of the mix in the developed unit were optimized using Response Surface Methodology (RSM) based on objective and subjective assessment of the dry mix and reconstituted payasam and were identified and validated as: steam pressure at 1.6 kg/cm2, scrapper speed 40 rpm and process time of 50 minutes. The performance of the developed mechanical unit was evaluated in terms of product quality (sensorial, physico-chemical and engineering attributes of optimized product) and techno-economical parameters (energy analysis of process, yield and cost of production). The mechanical unit consumed 1.22 kg steam per kg of water evaporation from the product and 0.48 kW electric energy per batch of production (2.2 kg dry mix). The cost of producing 1 kg of drycrystalized Palada payasam mix using the developed mechanical unit was estimated to be Rs. 105.09. The engineering properties of the product prepared under optimized conditions were evaluated as: angle of repose (27.23±0.64o), loose bulk density (681±12.89 kg/m2), packed bulked density (735.99±10.41kg/m2), particle density (1597.64±21.04kg/m2), porosity (59.36±1.24%) and water activity (0.432±0.003). Moisture sorption of the dry-crystallized mix was determined using DVS method and sample was observed to follow a Type-ΙΙΙ isotherm and the sorption data showed a good fit to the GAB model. X-ray diffraction (XRD) graphs of the product depicted sharp peaks validating the crystalline nature of product, while the XRD graphs for dry ada flakes confirmed their amorphous nature. The optimized samples of dry mix (prepared in the developed unit) and control (prepared manually) were packed in Al-foil laminate pouches (62 μm) and evaluated for their shelf stability at 30 oC for a period of 3 months. Physico-chemical, microbial attributes of the product and sensory analysis of the reconstituted mix monitored at regular interval, revealed that the product prepared in the mechanical unit had a stability identical to the control sample.ThesisItem Open Access DEVELOPMENT AND PERFORMANCE EVALUATION OF UNIVERSAL DISPERSER FOR DAIRY PROCESSING OPERATIONS(ICAR-SRS, BENGALURU, 2019) PRABHUDAS, DATIR RUPESH; RAVINDRA, MENON REKHAA universal disperser (product volume 3 L) was designed and developed in the form of a jacketed vessel enveloped by an outer insulation. Three multifunctional impellers, namely multivane churn impeller, pitched blade and saw tooth disc impellers were selected as attachments for the developed unit. An electric plate heater (2 kW) was integrated in the jacket volume of the developed unit along with the necessary control and indicators. The universal disperser was equipped with two motors for low speed and high speed operations and selected as per product characteristics. The developed unit was preliminarily tested for its performance using carboxyethylcellulose (CMC) solution as a test simulant. The developed unit was further investigated for different unit operations with three different dairy products viz., Lassi, Processed Cheese Spread and Recombined Milk. For lassi preparation, two independent parameters i.e. off-bottom clearance (OBC) (3, 6, 9 cm) and RPM (300, 400, 500) were selected and multivane churn impeller was identified as the better choice. The performance evaluation was adjudged in terms of the mixing index, mixing time, power consumption and overall sensorial acceptability. The process was optimized using Response Surface Methodology and it was recommended that lassi could be prepared at OBC of 4.84 cm at an impeller speed of 389 RPM. The overall acceptability was recorded 8.16±0.15 on 9-point hedonic scale while mixing time was 160±17.32 s. The power consumption was 34.21±0.70 W with a near unity mixing index. For the preparation of processed cheese spread, two independent parameters viz., temperature of processing (50, 65, 80 oC) and RPM (10000, 15000, 20000) were identified and the saw tooth impeller was selected for the operation. The output factors were evaluated in terms of mixing index, mixing time, power consumption, work of shear and overall sensorial acceptability. The product preparation was optimised at a temperature 80 oC and 19124 RPM. The mixing time was found to be 340±28.28 s and mixing index achieved was 0.974±0.003. Power consumption recorded was 292.88 ±2.28 W, while the work of shear (index of spreadibility) was measured and found to be 4.13±0.20 N.s. The overall acceptability was scored as 8.30±0.08 on 9-point hedonic scale. Similarly, the preparation of Recombined Milk (RM) was attempted with the saw tooth impeller using universal disperser. SMP, butter oil and water were used to formulate RM at different fat levels (1.5%, 3.0% and 4.5%) prepared at different processing conditions viz., temperature (20, 35, 50 oC) and RPM (10000, 15000, 20000) and mixing performance and product characteristics were evaluated as responses to optimise the process conditions to satisfactorily prepare recombined milk of desired fat content using the developed disperser. The study established that the developed universal disperser was versatile and could be successfully applied for different unit operations in the small and medium scale preparation of different dairy products.ThesisItem Open Access DESIGN AND DEVELOPMENT OF NANOPARTICLE COATED ANTI-FOULING HEAT EXCHANGER FOR MILK PROCESSING(ICAR-SRS, BENGALURU, 2019) MANJUNATHA B.M; Emerald, F. Magdaline EljeevaPlate heat exchanger (PHE) is the most popular equipment in dairy industries due to its ease of maintenance, cleanability, compactness, higher heat transfer coefficients and other features desirable in milk processing. However, fouling of its plates is a severe problem that impedes heat transfer, endangers the product quality and demands costly and time-consuming cleaning techniques. Among the number of techniques attempted to mitigate fouling of PHE, the modification of heat transfer surfaces by applying non-sticky materials like Teflon is a recent and potential technique. Present study was undertaken to design and develop a nanoparticle coated PHE for fouling mitigation by using polytetrafluorethylene (PTFE) and titanium dioxide (TiO2) as coating materials. A skid mounted module with two PHE units, balance tank, PID-controlled hot water generator, piping and pumping systems for milk and hot water was developed and evaluated. The PTFE and TiO2 in the ratio of 84:16 with a coating thickness of 20 m were selected based on the thermal conductivity of the coated SS 316 plates. The PTFE-TiO2 coating was done by spraying method on the plates of one PHE unit and the other PHE was left uncoated (control). Characterization of the coated surfaces was done by SEM-EDS, XRD, water contact angle, AFM and profilometer. Experimental trials were conducted for heat treatment of milk and paneer whey for 8 h using hot water as heating medium. Performance of the developed unit was evaluated in terms of overall heat transfer coefficients, foulants deposition and fouling resistance. The coating on testing for its adhesion strength using the cross-cut tape test was found to confirm to 5B grade as per ASTM-D3359. Average roughness of the SS 316 (uncoated) and PTFE-TiO2 surfaces measured with the profilometer were 0.2±0.02 and 0.74±0.09 m, respectively. The contact angles for uncoated and PTFE-TiO2 coated surfaces with distilled water, milk and paneer whey were 66.8±6.3° and 112.8±0.8°, 61±6.1° and 97.5±1.1°, and 82.44±2.1° and 103.8±1.03°, respectively. It indicated successful induction of hydrophobicity on the plate surface by coating. X-ray diffraction analysis indicated that the crystallite size ranged from 56.25 to 135.51 nm on SS 316 surface and from 4.19 to 173.10 nm for the coated surface. The EDS analyses revealed that the coated composite was distributed over entire surface of the substrate (SS 316) with 65.42% fluorine and 6.31% titanium by weight of the surface constituents, which came from the PTFE and TiO2 nanoparticles, respectively. The XPS of dried foulant deposits suggested the absence of PTFE and TiO2. Evaluation of the thermal performance of the developed PHE for processing of milk and paneer whey indicated mean overall heat transfer coefficients for uncoated surfaces ranged from 361.36 to 969.26 W/m2K, whereas for coated surfaces, it was from 314.46 to 352.45 W/m2K. The foulant deposition, analyzed using independent t-test, revealed that the coated surfaces realized significantly lesser (P<0.05) foulant deposition than by the uncoated surfaces for milk as well as whey. Thus, the evaluation established the anti-fouling properties of the PTFE-TiO2 coated surface.ThesisItem Open Access DEVELOPMENT OF SINGLE SCREW PERFORATED EXTRUDER FOR WHEY EXPULSION AND PANEER PRESSING(ICAR-SRS-NDRI, KARNAL, 2022) RAJASEKHAR TELLABATI; MENON, REKHA RAVINDRAPaneer is a dairy product which appeals to every age group and about 4-5% per of total milk produced in India is converted into paneer. Good quality paneer is characterized by its marble while colour, sweetish with mildly acidic taste and spongy body having close knit smooth texture. Paneer de-wheying and pressing is basically a consolidation process of the milk coagulum obtained by coagulating standardized milk. Trials were conducted on consolidation and extrusion of coagulum by designing suitable test cells and dies in association with a Texture Analyser. User defined macros were prepared and integrated in to the system software to analyse the creep and stress relaxation behaviour of the samples. The whey expression ratio and maximum strain during consolidation for optimized sample obtained were 20.26 and, 29.84 %, respectively. The mean force of extrusion increased from 27.17 to 41.57 N with increase in the die lead-in angle from 30 to 60 and speed of extrusion from 0.1 mm/s to 0.3 mm/s. The data obtained was applied for designing the variable pitch screw and the die geometry. A single screw perforated extruder for whey expulsion and paneer pressing was conceptualized and designed considering the data obtained in consolidation, extrusion studies and with basic engineering calculations and stress analysis. A customized die with heat exchanger was designed for blocking and cutting with cyclic timer to aid in texturizing the coagulum. The material of construction required for fabrication was optimized by the Von Mises stress analysis and the Finite Element Analysis confirmed the stability of the components under operating conditions. The preparation of Paneer in the developed single screw extruder was evaluated using two types of die profiles (circular, square), with 3 levels of auger speed (9, 12, 15 rpm) and 3 levels of angle of inclination of the barrel (0, 5, 10) and optimization was carried out using Taguchi L18 (21 x 32) experimental design. The product obtained was analysed for rheological parameters, moisture, colour profile and sensory scores for optimization. Calculations to predict extruder performance was modelled using Mathcad and the process modelling result indicated a net flow at die ranged from 60 to 70 kg/h with an energy consumption of 1.13 to 1.9 W.h/kg. The product characterization and rheological properties produced under optimized conditions in the developed machine were comparable to the conventional standardized product. The developed machine can be recommended for retail manufacturing of paneer on a small to medium scale enterprise.ThesisItem Open Access PROCESS ENGINEERING FOR NANOENCAPSULATION OF CATECHINS BY ELECTROSPINNING AND THEIR UTILIZATION FOR FORTIFICATION OF MILK(ICAR-SRS-NDRI, KARNAL, 2021) RAJUNAIK B; F. MAGDALINE ELJEEVA EMERALDNowadays, people are facing various health problems due to changing lifestyle and food habits, which lead to increased obesity, cardiovascular diseases, diabetes, cancer, etc. Consumers are therefore interested in traditional, natural and functional foods having positive health benefits. Catechins have been well-recognized for a wide range of health benefits including antioxidative, antiinflammatory, anti-carcinogenic, anti-hypertensive and lipid-lowering effects. However, catechins in their free form undergo epimerization, degradation and oxidation reactions during food processing and storage, which limits their use in fortification and development of functional foods. The oral administration of catechins needs an additional protection to increase their bioavailability and physiological targeting. Electrospinning is a one-step encapsulation technique to produce bioactivesloaded fibres of nano-scale range with higher encapsulation efficiency and enhanced functionality. In this study, selection and screening of various biopolymers were done for nanoencapsulation of catechins by determining the physical and engineering properties of the polymer solutions and computing the group of dimensionless numbers influencing electrohydrodynamics of the solutions. The viscosity of polymers solutions ranged from 7.6 to 746.7 mPas, while the suitable viscosity range for electrospinning was 100 to 600 mPas. The polymer solutions showed slight shear thinning behaviour (n=0.8621-0.9974), which was necessary for electrospinning. Loss modulus (1.047-7.929 Pa) of polymer solutions was more than storage modulus (0.011-0.049 Pa), confirming that the feed solutions were viscoelastic liquids, which is a desirable characteristic for electrospinning. The inequality conditions (Be≥2; Oh≥1; De≥1; We≤30 and De≥Oh≥1) for formation of uniform nanofibres without beads were satisfied by zein, pullulan and combination of zein-fructo-oligosaccharides (80:20) polymers. However, in the initial evaluation trials, clean, beadfree and continuous nanofibres were produced only by zein and pullulan. Hence, these two biopolymers were selected to load catechins into electrospun nanofibres individually. Zein of three concentrations (15, 18 and 21% w/w), and process conditions such as three applied voltages (16, 20 and 24 kV) and two feed rates (0.5 and 1.0 mL/h) were selected for electrospinning. For production of catechins-loaded pullulan nanofibres, concentrations of 10, 12 and 14% were selected, while other electrospinning factors remained the same. For each polymer, Taguchi L18 (21×32) orthogonal array design was used for optimization of electrospinning process conditions with fibre diameter and encapsulation efficiency as response factors. The control factors with the highest mean signal to noise (S/N) values were selected. The optimized conditions of electrospun catechins-loaded zein nanofibres were 18% concentration, 0.5 mL/h feed rate and 20 kV applied voltage, while for pullulan-based catechins-loaded nanofibres, the optimal conditions were 12% concentration, 0.5 mL/h feed rate and 20 kV applied voltage. The distance between spinneret and collector was maintained at 18 cm. SEM micrographs showed that zein at 15% and pullulan at 10% concentrations yielded only beaded nanofibres. In contrast, zein at 18 and 21% concentrations, and pullulan at 12 and 14% concentrations yielded clean, beadfree and continuous nanofibres. At optimized conditions, the mean fibre diameter and encapsulation efficiency of catechins-loaded zein nanofibres were 94.3 nm and 92%, whereas for catechins-loaded pullulan nanofibres they were 66.6 nm and 92.9% respectively. In comparison to zein-based nanofibres, the pullulan-based nanofibres had better encapsulation efficiency and smaller mean fibre diameter. FTIR and XRD analyses confirmed that catechins were successfully encapsulated. AFM images showed that the catechins-loaded nanofibres had cylindrical morphology with non-porous topography. Comparison of Ra values revealed that pullulan-based nanofibers were relatively smoother as compared to zeinbased nanofibers. The hydrodynamic diameter, zeta potential and polydispersity index (PDI) at optimized conditions were 172.3 nm, -26.3 mV and 0.15, respectively for zein-based catechins-loaded nanofibres, and for pullulan-based catechins-loaded nanofibres the corresponding values were 182.4 nm, -28.4 mV and 0.14. Low PDI and negative zeta potential indicated that nanofibres would be stable and homogeneous in solutions or fortified foods. Fortification of milk with catechins-loaded nanofibres produced at optimized conditions did not alter its composition and physico-chemical properties. Release of catechins from fortified milk was in a sustained and controlled manner. Sensory evaluation using Fuzzy logic approach confirmed that milk fortified with pullulan-based catechinsloaded nanofibres was ranked first followed by that of zein-based nanofibres.ThesisItem Open Access DEVELOPMENT OF COCONUT SHELL POWDERBASED BIOCOMPOSITES FOR PACKAGING OF SELECT DAIRY PRODUCTS(ICAR-SRS-NDRI, KARNAL, 2021) ADARSH M. KALLA; F. MAGDALINE ELJEEVA EMERALDBiodegradable packaging materials developed using agricultural wastes can be a promising alternative to non-degradable synthetic polymers. In this context, the present study was envisaged to utilise the coconut shell powder (CSP) as a biodegradable packaging material for select dairy products. CSP was used to make containers and to extract cellulose, which was utilised as reinforcing material in polyvinyl alcohol (PVA) and casein matrix films. The development of CSP based container with different binders such as acacia gum, guar gum, starch, gluten and sodium alginate were unsuccessful due to breakage and sticking to die. The setup used to make containers was later modified by providing guide rods and hydraulic press but no satisfactory shaping of containers were obtained. Cellulose was extracted from CSP by alkalisation and delignification methods. The average yield and moisture content of the extracted cellulose were 27.5% of the initial weight of CSP and 2.5% d.b., respectively. Flow properties such as bulk density, tapped density, angle of repose and porosity of extracted cellulose, CSP and commercial cellulose were found to be 368.80, 500.90 and 303.90 kg/m3, 493.80, 682.50 and 452.30 kg/m3, 44.18, 43.17 and 55.75° and 0.71, 0.69 and 0.79, respectively. The size of extracted cellulose fibres was observed from scanning electron micrographs (SEM) as 5-20 μm. Energy dispersive X-ray spectroscopic analysis confirmed the absence of chemicals used for cellulose extraction. Atomic force microscopy revealed that the extracted cellulose had mean roughness of 1.37 nm. X-ray diffractograms (XRD) revealed the crystalline nature of extracted cellulose, with crystallinity index of 65.9%. Fourier transform infrared (FTIR) spectra confirmed the absence of lignin and hemicelluloses in the cellulose extracted from CSP. D-optimal mixture design was used to optimise the ingredients such as CSP, PVA and casein in the cast films. The viscosity of film forming solutions (FFS) ranged from 3.88 to 87.41 mPa.s, which also displayed non-Newtonion behaviour. The rheological data of all FFS were best fitted to Casson’s model with R2 ranging from 0.995 to 0.999. The viscoelasticity of FFS showed linear and higher value of loss modulus over the entire shear rate range, indicating dominant viscous behaviour. The FFS were formed into films using film casting method. The thickness of films ranged from 0.256 to 0.312 μm. The mechanical properties such as tensile strength, tensile strain and modulus of elasticity were measured, and were found range from 3.20 to 7.20 MPa, 8.66 to 104.16% and 5.67 to 83.42 MPa, respectively. Moisture content and solubility were analysed and found to be varied from 25.56 to 16.55% d.b and 17.47 to 27.44%, respectively. Transparency of films ranged from 1.50 to 4.61 AU nm/mm. Lightness and whiteness index value of films ranged from 38.23 to 72.03 and 38.22 to 71.12, respectively. The water vapour permeability of biocomposite films ranged from 8.09×10-10 to 11.60×10-10 g/msPa. The composite films containing higher percentage of PVA were more resistant to biodegradation. The SEM micrographs confirmed the dispersion of cellulose in casein-PVA polymer matrix. The oxygen permeability values were also within the range. The FTIR and XRD results of films indicated good interaction between cellulose and polymer matrix. PVA, casein and cellulose in the ratio of 4:3:2 was found to be optimum with respect to film properties. Moisture sorption isotherms of PVA, casein and optimised biocomposite films at 25, 30 and 40°C followed Type-II BDDT classification. The GAB model best fitted the moisture sorption data of all samples as evident from R2 and RMSE values of nearly 1 and less than 10, respectively. The optimised biocomposite film was used to package paneer and storage study was done at 7±1°C for 9 days. The physico-chemical and microbiological analysis revealed that the biocomposite film was comparable with LDPE pouches. Organoleptic studies revealed that the paneer packaged in composite film had statistically acceptable sensory scores except for its body and texture, and had slightly less shelf-life than those packaged in LDPE pouches.ThesisItem Open Access NANOENCAPSULATION OF CASEIN-DERIVED PEPTIDES THROUGH COAXIAL ELECTROSPINNING: FABRICATION OF NANOFIBRES AND THEIR CHARACTERIZATION(ICAR-SRS-NDRI, KARNAL, 2021) DEVARAJU R; P. HEARTWIN AMALADHASThe study was aimed to develop food-grade nanofibres and to encapsulate casein-derived peptides by uniaxial and coaxial electrospinning. Peptides were produced by hydrolysis of 5% (w/w) casein using alcalase and chymotrypsin alone and with their combinations at their optimum pH and temperature conditions. Peptides of <3 kDa fractions obtained by ultrafiltration of hydrolysates produced by combined action of both enzymes exhibited the highest antioxidant activity of 61.77%, which was equal to 3.32 μM TEAC/mg peptide, and ACE inhibition activity of 72.65%. Screening and selection of biopolymers for encapsulation of peptides into nanofibres were done based on rheological properties and electrohydrodynamics of feed solutions, which govern their fibre forming ability. Above 10% concentration, pullulan satisfied the inequality conditions of De≥Oh≥1 required for electrospinnability, while Berry number confirmed the molecular chain entanglement needed for fibre formation at concentrations above 10%. Pullulan at 10, 12 and 14% (w/w) concentrations were used as shell solution and peptide-loaded core solution (1:0.2 pullulan to peptide ratio) for coaxial electrospinning of peptides. Similarly, peptide-loaded pullulan solution (1:0.1 pullulan to peptide ratio) at same concentrations was used for uniaxial electrospinning. The storage and loss modulus (Gʹ and Gʹʹ) confirmed the viscoelastic ‘liquid-like’ behaviour of both uniaxial and coaxial electrospinning feed solutions. The viscosity of uniaxial and coaxial solutions was nearly constant with increasing shear rate without yield stress. Power-law best fitted to the flow behaviour of all pullulan solutions with R2 ranging from 0.998 to 0.999. The values of Power-law flow behaviour index ranged from 0.988 to 0.993, confirming the near Newtonian behaviour. The critical voltage required to initiate jet formation ranged from 16.74 to 17.20 kV and 16.78 to 17.33 kV for uniaxial and coaxial electrospinning solutions. Factorial analysis showed that the effects of concentration, feed rate and voltage were highly significant (p<0.001) on mean fibre diameter and encapsulation efficiency of both uniaxial and coaxial electrospun nanofibres. The mean fibre diameter ranged between 60.45 and 133.05 nm, while encapsulation efficiency ranged from 72.95 to 86.04% for uniaxial electrospun nanofibres. Similarly, the mean fibre diameter ranged between 64.65 and 141.17 nm, while encapsulation efficiency ranged from 72.39 to 97.02% for coaxial electrospun nanofibres. FESEM and AFM micrographs of uniaxial and coaxial electrospun nanofibres confirmed the formation of clean beadfree nanofibres above 10% pullulan concentration. FTIR of peptide-loaded nanofibres revealed that interactions between pullulan and peptide were of physical nature rather than chemical interactions and confirmed the nanoencapsulation of peptides in both uniaxial and coaxial electrospun nanofibres. XRD diffractograms revealed the non-crystalline structure of both uniaxial and coaxial nanofibres. Zeta potential of coaxial and uniaxial electrospun nanofibres varied from -15.6 to -24.6 mV and -14.0 to -26.5 mV, respectively, while PDI of coaxial and uniaxial electrospun nanofibres ranged from 19.8 to 40.5% and 14.8 to 35.6%, respectively. High zeta potential and low PDI were indicative of better stability against aggregation caused by van der Waals forces of inter-particle attractions and homogeneity in size of nanofibres. XPS surface chemical analysis confirmed the nonexistence of peptides on the surface of core-shell nanofibres, indicative of good encapsulation of peptides within the nanofibres. The peptides from coaxial electrospun nanofibres showed sustained release to the extent of 18.4% as compared to 34.3% in uniaxial electrospun nanofibres after 2 h in gastric pH condition. Similarly, after 6 h in intestinal pH condition, the release of peptides from coaxial and uniaxial electrospun nanofibres was 53.7 and 78.3%, respectively. In comparison, the release of free peptides after 2 h of gastric pH and 6 h of intestinal pH conditions were 73.62 and 98.63%, respectively. The burst release of peptides from coaxial electrospun nanofibres was less as compared to that from uniaxial electrospun nanofibres. The release data kinetics fitted best to Kosmeyer-Peppas, Peppas-Shalin and Kopcha models, and release of peptides occurred through diffusion and erosion mechanisms. The release mechanisms of peptides from both uniaxial and coaxial electrospun nanofibres were similar. The antioxidant activity (% DPPH radical scavenging activity) of peptides was 58.16%, while it was 56.20% and 54.10% for coaxial and uniaxial electrospun peptide-loaded nanofibres, respectively. Physico-chemical and organoleptic qualities of milk fortified with coaxial and uniaxial electrospun nanofibres did not show noticeable difference as compared to control. Milk fortified with uniaxial and coaxial electrospun nanofibres were accepted well with score of 8.7 and 8.8 as compared to 8.5 of control.
