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ThesisItem Open Access Development of enzyme based chromogenic strips for detection of selected adulterants in milk(College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022-09) Muktan, Priya; Raquib, MasukThe present investigation was carried out to develop an enzyme based chromogenic strip for detection of selected adulterant in milk. The experiment was carried out in the Department of Livestock Products Technology, All India Coordinated Research Project on Post Harvest Engineering and Technology and Department of Veterinary Biochemistry, College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati- 781022. An enzyme based chromogenic test strip using Whatman filter paper grade 602 and Whatman filter paper No. 1 was developed for the detection of glucose, starch and urea in milk using glucose oxidase, amyloglucosidase and urease enzyme in the presence of potassium iodide for starch and glucose and phenol red for urea as an indicator. The activity of the test strip was validated in both raw and processed milk spiked with the respective adulterants. All the enzyme based test strips were able to detect 2mg/ml of glucose, starch and urea with definite ring formation within a specified time period. The response time for the detection of glucose, starch and urea in milk was noted at 31.22±0.014 and 30.00±0.05, 128.3±0.88 and 129±0.57 & 99 ±0.57 and 109.67 ±0.88 sec, respectively in Whatman filter paper grade 602 and Whatman filter paper No. 1 at a pH of 4.5, 4.5 and 8.0 and a chromogenic substrate concentration of 40, 50 and 1 mg/ml. The optical density of glucose, starch and urea was found to be almost linear. As the concentration of the substrate increase the optical density value tends to increase proportionately. The test strip was tested for true positive and true negative results. The limit of detection for glucose, starch and urea were found to be 1.0, 2.0 and 0.8 mg/ml, with response time of 1, 4 and 3 min, respectively. To see the effect of different processing condition on the ability to degrade glucose, starch and urea in milk, all the test strips showed positive response except in household boiling condition wherein the response was delayed by a few min. The enzyme based test strip were 100 percent specific for detection of glucose, starch and urea as presence of similar types of compounds did not interfere with the positivity rate of the strips which was verified with help of confusion matrix. The shelf life of enzyme based chromogenic glucose, starch and urea test strips were found to be 40 and 30, 34 and 30 & 42 and 34 d, respectively for Whatman filter paper grade 602 and Whatman filter paper No. 1, respectively when stored under refrigerated storage (7±1oC) and ambient storage (29-32oC) condition in airtight glass containers.ThesisItem Open Access Quality characteristics of soy milk blended yoghurt(College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022) Khatun, Arifa; Borpuzari, TA study was carried out to evaluate the quality characteristics of soy milk blended cow’s milk yoghurt. The study was carried out in the laboratories of the Department of Livestock Products Technology, the All India Coordinated Research Project on Post-Harvest Engineering and Technology, the Department of Veterinary Biochemistry, College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati- 781022 and in the Central Analytical Instrumentation Facility, Guwahati Biotech Park Incubation Centre, Amingaon, Kamrup, Guwahati-781031 during the period from December, 2021 to September, 2022. Organic whole soybeans procured from the local super markets were used for preparing sprouted and unsprouted soy milk. The NCDC 144 obtained from the National Dairy Research Institute, Karnal was used @ 3% (v/v) as yoghurt starter culture in the study. The effects of addition of soy milk on the pH, per cent lactic acid content, free fatty acids, flavour and colour profile, proximate composition, microbiological quality, sensory scores and the best before end of the cow’s milk yoghurt were studied. A gradual decrease in the pH values of the Control samples as well as in all the samples of the Treatment groups was noted. Fatty acids and flavour compounds were identified with the help GC-MS. The colour profiling revealed that L, a and b values were the highest in control samples followed by T2 group while the samples of T1 group showed the least values for these colour components. The samples of T2 group contained the maximum mean values of 4.23±0.02, 19.65±0.10 and 1.26±0.00% for protein, total solids and ash, respectively, while the Control samples showed the maximum mean value of 4.37±0.03 and 82.96±0.12% for fat and moisture, respectively. The protein content of the cow’s milk yoghurt incorporated with 25% of soy milk had higher protein content than the cow’s milk yoghurt. Addition of sprouted soymilk increased the per cent protein content of the cow’s milk yoghurt than those incorporated with unsprouted soymilk. The highest mean TVC of 9.13±0.01 log10cfu/ml was recorded in the samples of the T2 group which might be due to rapid growth of the added starter organisms accelerated by the synergistic effect of the germination metabolites of soybeans. Coliforms, E. coli, Salmonella, Shigella, Staph. aureus and yeast and moulds were not detected in any of the samples. The cow’s milk yoghurt prepared with 25% unsprouted soymilk had higher contents of caproic, caprylic, and lauric acids over the control samples. The yoghurt prepared with 25% sprouted soymilk had higher concentrations of margaric, palmitoleic, proprionic, tricosylic, tridecylic and vaccenic acids as compared to the control as well as the unsprouted samples. These free fatty acids might have contributed to the typical flavour of soy blended cow’s milk yoghurt. The cow’s milk yoghurt blended with 25% of unsprouted and sprouted soy milk enjoyed identical panel acceptance for the appearance, colour, body and texture, and flavour characteristics indicating that soy milk could be successfully blended with cow’s milk up to 25% in yoghurt without affecting its sensory properties. However, the cow’s milk yoghurt was more preferred for its taste as compared to the soy milk blended yoghurts. Cow’s milk yoghurt blended with 25% soy milk had the ‘Best Before End’ of 5d at refrigeration temperature.ThesisItem Open Access Effect of rice beer and phyto-ingredients on certain quality characteristics of duck meat product(College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2023) Boro, Pompi Rani; Laskar, S KThe study was conducted in the Department of Livestock Products Technology, Assam Agricultural University, Khanapara, Guwahati-22 to develop a duck meat product incorporating rice beer, phyto-ingredients and spices as marinating ingredients along with control without affecting the physico-chemical, microbial, organoleptic qualities and shelf life of the meat. A total of five batches of marinated duck meat comprising of 4 different treatments in each batch were prepared. Ducks were collected and slaughtered hygienically and marinated. The marinades were prepared by using rice beer, spice paste and phyto-ingredients. The marinated samples are grouped into following treatments for control (meat and spice paste), Treatment 1 (meat and rice beer), Treatment 2 (meat, phyto-ingredients and spice paste) and Treatment 3 (meat, spice paste, rice beer and phyto-ingredients). The marinated samples were vacuum and aerobically packed and stored in refrigeration temperature for 24 hrs. After these periods, the samples were subjected to various quality assessments. Shelf life studies conducted at interval of 5 days for vacuum packed samples, whereas, aerobically packed samples were assessed for shelf-life studies at an interval of 3 days. The results of the investigation are as follows: The alcohol content (%) of rice beer found to have 6.02±0.2. The pH value was 3.58±0.09 and the antioxidant activity (%) was found to have 16.12±0.13. The results with respect to pH, tyrosine and TBA of marinated duck meat were found to be significantly (P<0.01) higher when compared to control samples. Mean cooking yield was found to be higher in control samples as compared to the treated samples. The cooking yield was significantly lower in treated samples as compared to that of control samples. The mean percent of proximate composition of products showed similar trend for both aerobic and vacuum packaging systems. Moisture was high in the Treatment 3 samples as compared to that of control samples, whereas, crude protein, ether extract and total ash was high in control samples. The mean values of moisture, crude protein, ether extract and total ash showed significant differences among the control and treated samples but no significant effect could be seen in both the packaging conditions. The mean values of colour profile showed no significant differences between the control and treated samples and also no significant effect in both the packaging conditions. The data generated for aerobic packaging method revealed marginally higher L* values. The L* value was lower for treated products than that of control products. Redness (a*) followed a decreasing trend in all the treated products as well in control products. Slight decrease in yellowness in vacuum packaged duck meat products. ii The mean values of texture profile also showed similar trend in both the packaging systems. The hardness values showed a decreasing trend in treatment 3 as compared to control samples in both the packaging systems. However hardness values were marginally lower in vacuum packaged samples when compared to aerobically packaged samples. Significant differences (P<0.01) could be observed in the control and treated samples for springiness and chewiness, whereas, cohesiveness followed an increasing and decreasing trend and no significant (p>0.05) differences among all the treated samples. The resilience followed uniformly decreasing trend from control to T3 samples The sensory evaluation showed no significant differences (Appearance, colour, flavour and tenderness), whereas, significant differences were observed for juiciness and overall acceptability. The microscopic study in both (scanning electron microscope and light microscope ) revealed swelling of muscle fiber and decrease in inter fibrillar spacing between the muscle fibers and disruption of connective tissue membranes due to use of marinating ingredients. The microbiological quality studies revealed that there is a significant increase (P<0.01) in control samples compared to treated samples during the entire storage periods in both the packaging systems, whereas, total psychrophilic count could not be detected on 1stand 5th day of storage in vacuum packaging but on 10th and 15th day it increases in the storage periods. Similarly for aerobically packaging systems, TVPBC were not detected on 1st day of storage but on 3rd, 5th and 7th day of storage it increases in the storage periods. The Yeast and Mould count and Coliform count were absent in all the storage periods in both the packaging systems. The Sulphite Reducing Clostridial organisms and salmonella were also found to be absent in all the samples for both the packaging systems. The shelf life studies of marinated duck meat were studied on the basis of pH, tyrosine, TBARS value, microbiological quality and visible colour and odour changes of the products at refrigeration temperature. Vacuum packaging system was found to be better than the aerobic packaging system. Based on the investigation, it can be concluded that an acceptable marinated duck meat product can be developed for future commercial exploitation.ThesisItem Open Access Interaction studies of microbial enzymes and phytochemicals of Bael (Aegle marmelos) in flavour enhancement cow's milk ghee(College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022) Saikia, Rashmi Rekha; Borpuzari, TrishnaA study was conducted to develop flavour and colour enhanced cow’s milk ghee using starter cultures as a source of microbial enzymes and phytochemicals of bael (Aegle marmelos) fruit pulp extract. The experiment was conducted in the laboratories of the Department of Livestock Products Technology, the All India Coordinated Research Project on Post-Harvest Engineering and Technology, the Department of Livestock Production and Management, the Department of Veterinary Biochemistry, College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati–781 022; and the Central Analytical Instrumentation Facility, Guwahati Biotech Park Incubation Centre of the Indian Institute of Technology, Amingaon, Kamrup, Guwahati-781 031 during the period from August 2020 to April 2022. Lactococcus lactis ssp. lactis var. diacetylactis and yoghurt cultures of Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus were used @ 3% (v/v) in the study. Bael pulp extract was added @ 1% (v/v) to the treatment groups. Cow’s milk ghee was prepared by the heat clarification method. The flavour and colour qualities, FFA contents, antioxidant compounds, sensory attributes, proximate composition and shelf-life of the cow’s milk ghee thus prepared were studied. The ghee was stored at ambient temperature to study the shelf-life. A total of 34 flavour compounds were detected in the samples of the treatment groups as well as the reference sample by GC-MS studies. Identical numbers of FFA were also detected in the ghee samples. The flavour of the ghee was attributed by the FFA along with the other flavouring compounds like the alcohol, hydrocarbons, ketones, terpenoids, organic acids and 9 other compounds identified in the ghee samples. Ascorbic acid, thymol, phytol and β-sitosterol were the four antioxidant compounds detected by GC-MS. The maximum radical scavenging activity (60.160±0.541%) was observed in the sample of T4. Bael pulp extract added ghee samples had higher DPPH inhibition activity as compared to the other groups and the reference sample. Colour component b* was found in higher values in bael pulp extract added ghee samples. Highly significant positive correlation was found between the sensory evaluation scores for colour and the colorimetric assessment of the colour components (b* value). Higher panel ratings for flavour and colour of the samples of T4 group indicated that bael pulp extract indeed had a positive effect on the flavour and the colour characteristics of cow’s milk ghee. The moisture and ash contents of the ghee were highly significantly influenced by the starter cultures and addition of bael pulp extract while only significant difference could be found in their protein content. Shelf-life study was done based on the FFA and peroxide values. Correlation studies revealed a highly significant difference between FFA and PV while a negative correlation existed between the FFA x antioxidant activity and PV. A gradual increase in FFA and PV along with the increase during the storage period was found in all the treatment groups. Even after 6mon of storage, FFA and PV were found to be much lower than those recommended by the FSSAI (2016). From the study it was found that the starter culture Lc. lactis ssp. lactis biovar diacetylactis used in the study in combination with the bael pulp extract produced cow’s milk ghee with improved flavour and colour attributes and had an extended shelf-life at room temperature.ThesisItem Open Access Detection and deactivation of antimicrobial residues in pork(College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022-09) Debbarma, Param; Laskar, S KThe present study aims to detect antimicrobial residues in collected pork samples, isolation and in-vitro study of the resistance pattern of meat-borne pathogens (Escherichia coli, Salmonella spp. and Staphylococcus aureus) against 12 commonly used antimicrobials in pig husbandry and effect of different cooking methods (viz, boiling, roasting and microwaving) on deactivation/inactivation of antimicrobial residues. The preliminary screening of 261 pork samples by microbial inhibition assay using endospores of Bacillus subtilis MTCC 441 as test organism revealed that none of the samples were positive for antimicrobial residues except 3 (three) which were doubtful to have traces of antimicrobial residues. A total of 80 pork samples were further screened by Ultra-Fast Liquid Chromatography system (Model: Shimadzu Prominence LC-20AD, Detector-SPD-20AUV/ Vis; C18 Column: BDS Premium, 250 mm x 4.6 mm, 5 m) to detect OTC, TTC, CIP and GEN residues. OTC and CIP residues were detected in 2.5% and 1.25% of the samples, while none of the samples detected TTC and GEN residues. The overall recovery rate of Escherichia coli, Salmonella spp. and Staphylococcus aureus from the pork samples were 28.75%, 9.09% and 31.25%, respectively. All the isolates showed variable ranges of resistance against the tested antimicrobials. Highest resistance was recorded against ampicillin (75-100%), followed by trimethoprim (37.5-100%), cefepime (25-75%), nalidixic acid (12.5-62.5%), sulfafurazole (0-37.5%), ciprofloxacin (0-37.5%), chloramphenicol (0-37.5%), ceftriaxone (0-25%) and amoxiclav (0-12.5%). All the isolates however, recorded 100% sensitivity against amikacin, gentamicin and tetracycline. The effect of cooking viz. boiling, roasting and microwaving revealed significant reduction (p˂0.001) in the residual concentration of antimicrobials (OTC, TTC, CIP and GEN). Cooking by microwaving recorded highest reduction (44.48-91.06%) followed by roasting (32.11-85.92%) and boiling (22.02-73.33%). Thus, cooking temperature and time can have a significant effect on the losses of antimicrobial residues and provides an additional safety margin to the consumers.ThesisItem Open Access Effects of different methods of smoking and levels of fat on certain quality characteristics of buffalo meat sausages(College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022) Mali, Anindita; Laskar, S KBuffalo meat sausages were developed employing different methods of smoking and levels of fat to obtain a healthy product with good shelf-life properties and economic feasibility. Three primary treatment groups were prepared, namely- T1 (20% fat), T2 (10% fat + 10% inulin), T3 (7.5% fat + 12.5% inulin), which were subjected to three subgroup A (Conventional smoking), B (3% Liquid smoke), C (7% Liquid smoke). The control was prepared with 20% fat without any sub-treatments. 5 batches of buffalo meat sausages were prepared and evaluated for various important qualitative parameters on the 1st, 7th, 14th, 21st and 28th day of refrigerated storage, including estimation of PAH and cost of production. The ES and CY were seen to significantly increase with the replacement of fat with inulin and the highest was observed in the treatment group T3. The pH value decreased significantly (P<0.05) in all the treatments in comparison to the control, the lowest of them being T2A (5.69 ± 0.09). With higher inclusion of inulin, the aw, and WHC significantly (P<0.05) increased in the treatment. The TBARS values were significantly (P<0.05) lower in the treatment group T3, ranging (from 0.30 ± 0.02 to 0.34 ± 0.03). The tyrosine value did not vary significantly among the control and treatments. However, T3B (10.14 ± 0.38) and T3C (10.10 ± 0.44) were significantly lower. The proximate analysis depicted treatment T3C to have the highest moisture content of 68.62 ± 0.45. The protein content did not vary significantly between the control and treatment and ranged from 19.05 to 19.72%. The fat content reduced from 19.12± 0.46 to 8.08± 0.33 when inulin was substituted for fat. The highest fat per cent was observed in T1A (19.12 ± 0.46) and the lowest inT3C (8.08 ± 0.33). The ash content increased from 1.04 ± 0.07(control) to 2.63 ± 0.06 (T3C) with the addition of inulin at higher percentages. The lowest calorific value was obtained in T3C (155.79 ± 1.42), corresponding to the lowest level of added fat. The mean log10 cfu for total plate count showed significant (P<0.05) differences between the control and other treatments, without any significant difference among the treatments. The buffalo meat sausages were not detected for E. coli, yeast and mould, Salmonella and Staphylococcus. The TPA results showed that with higher inclusion of inulin as a fat replacer, the hardness, springiness, chewiness and resilience significantly increased. However, cohesiveness was not significantly affected. The colour profile study depicted a significant increase in the L* value, with higher inclusion of inulin (54.95 ± 0.22) in T3B; however, the a* values were inversely co-related to L*. The b* did not vary between treatments and control, except for treatment T3C. The estimation of PAH depicted that the potent carcinogen Benzo(a)pyrene was absent in control and all the treated samples. However, the PAH compounds, Fluoranthene and Chrysene, were observed in the samples in both conventionally smoked and liquid smoke added products. The concentration of Fluoranthene differed significantly and was found to be the lowest in T1B (15.10 ± 0.00) and the highest in T2C (53.47 ± 9.04), while Chrysene content did not vary significantly and ranged from (32.27 ± 0.97 to 38.37 ± 1.77). Considering the above parameters, T2 was found to be better than other treatment groups, and therefore the sausage samples of T2, along with the control, were subjected to the organoleptic evaluation. The subjective evaluation revealed that the conventional smoking treatment T2A had the highest scores for appearance, colour, flavour, texture and overall acceptability.The developed buffalo meat sausages were found to be stable for up to 21 days under vacuum packaging at a refrigeration temperature (4 ± 10C), after which the microbial counts exceeded the FSSAI standards. The cost of production was calculated based on the market prices of the raw materials. The highest was observed for T3C (Rs. 763.45/kg), while the lowest was for control (Rs. 518.00/kg). Based on the findings of the present study, treatment group T2, in particular, T2A, was the best among all the treatments.ThesisItem Open Access EFFECTS OF BLACK RICE EXTRACT ON QUALITY CHARACTERISTICS OF DUCK MEAT NUGGETS(College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, 2022-01) SAIKIA, KALPITA; Laskar, Saurabh KumarDuck meat nuggets were prepared by incorporating three different concentrations (0.5%, 0.9% and 1.3%) of black rice ethanol extract (BREE) and other non-meat ingredients to find out the best formulation which can be stored for a reasonable time at refrigeration temperature without affecting their physico-chemical, organoleptic and microbiological qualities. Nuggets were cooked by two different methods, i.e. steam cooking and oven cooking. The formulations prepared in the steam cooking method were CS (0% BRE), T1S (0.5% BRE), T2S (0.9% BRE) and T3S (1.3% BRE) and formulations prepared in the oven cooking method were CD (0% BRE), T1D (0.5% BRE), T2D (0.9% BRE) and T3D (1.3% BRE). A total of five batches of nuggets of each formulation were prepared, and different quality parameters were evaluated. In oven cooking nuggets were cooked in a preheated hot air oven at 120°C till the internal temperature reached 75 ± 2°C, Steam cooking nuggets were done in a cooking vat at 80ºC for 45min. After that, these were packed in food-grade polyethylene bags, stored under refrigeration temperature and evaluated for various quality traits viz., Water Holding Capacity (WHC), pH, Water activity (aw), Thiobarbituric acid (TBA) value, Total Plate Count (TPC), Total Viable Psychrophilic Bacterial Count (TVPBC),Coliform count, Yeast and Mould count, Staphylococcus count, Antioxidant activity, Colour Profile on 1st, 5th, 10th and 15th days of storage. In addition, Emulsion Stability, Cooking Loss, Proximate Composition, Organoleptic qualities, and Texture Profile of the products were estimated on the day of production (1st day). The production cost of duck meat nuggets were also calculated to find out the best and most economic formulation. Emulsion stability (ES), Cooking loss and proximate composition of duck meat nuggets did not show significant (P > 0.05) differences between control and Black Rice Extract treated products both in steam cooking and oven cooking. The pH values did not differ significantly between the treated and control formulations in both the cooking methods. However, there was a significant (P 0.05) among the treatments and control formulations in either of cooking methods. A significant (P 0.05) differences were observed between control and treated products in terms of hardness, fracturability and chewiness in both the cooking method, However, springiness, cohesiveness and resilience values of texture profile showed significant (P < 0.01) differences between the product groups. The results of colour profile studies showed that the redness (a*) value increased significantly (P < 0.01) with the increased incorporation of Black Rice Extract, however during storage, the value decreased significantly in all the formulations. The lightness (L*) and Yellowness (b*) values decreased significantly (P < 0.01) with the incorporation of BRE, although, the b* value ii decreased, and the L* value increased significantly in all the formulations & in both the cooking methods during storage periods. The incorporation of higher concentrations of black rice extract resulted in higher DPPH free radical scavenging activity. During storage (up to 15 days) it had shown a significant decreasing trend of antioxidant activity in all the formulations and in both the cooking methods. The higher concentrations of black rice extract resulted in higher total phenolic content. The taste panel evaluation studies in respect of overall acceptability scores of duck meat patties involving all the eating quality parameters revealed that the 0.9% BRE treated products (T2) had the highest overall acceptability scores. Though, the panel scores of nuggets recorded for all other treatment groups were found acceptable. Estimation of production cost of duck meat nuggets indicated that T3 formulation products were more economical than the control and other treated products. Based on the results obtained in the study, it might be concluded that duck meat nuggets could be prepared satisfactorily on the addition of up to 1.3% concentration of BRE and can be stored safely up to 10 days under refrigeration temperature.
