Food Technology

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https://hdl.handle.net/20.500.14540/128

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Improvement on Traditional Millet Fermentation Process and Its Brewing Quality Assessment
(Faculty of Food Technology, 2013) Karki, Dhan Bahadur
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Technological and Nutritional Evaluation of Sel-roti
(Faculty of Food Technology, 2013-05) Katawal, Surendra Bahadur
Sel-roti is a popular and delicious rice-based, sweet, puffed, spongy, deep-fat fried, ring shaped doughnut like Nepalese indigenous food product prepared from the batter of rice flour, ghee and sugar. Sel-roti making technology is an indigenous technology of Nepal. A survey study of 126 respondents comprising different casts, ethnicity, religion, age, sex from different district of Eastern and Central Development Regions of Nepal was conducted to gather the information on ingredients, recipe, equipments and processing methods of Sel-roti by using questionnaires. The factors affecting quality, storage and shelf life and also production, marketing, socioeconomic and cultural aspects were gathered and documented. It showed that the variety and age of rice, type of ingredients, method of preparation, and storage condition influence the quality and self-life of Sel-roti. To study the effect of particle size of rice flour on the physical properties, sensory quality and textural attributes of Sel-roti, the soaked rice was ground into flour with the help of iron mortar and pestle, analyzed for particle size distribution by using standard sieves and separated into three particle size categories i.e. coarse (>890 µm), medium (450-225 µm) and fine (<120 µm). They were mixed in different proportions; analyzed their distribution and calculated mean particle diameter; prepared Sel-roti, and analyzed for bulk density & fat uptake; and sensory and texture attributes were evaluated by trained panelists. The experiments were conducted in triplicate. The results obtained showed good positive correlation between mean particle size and the bulk density (r = 0.97, p≤ 0.05) and a good negative correlation between mean particle size and fat-uptake (r = -0.90, p≤ 0.05). Also, good correlations of mean particle size with sensory texture attributes like smoothness (r = -0.97, p≤ 0.05), hardness (r = 0.99, p≤ 0.05), fracturability (r = 0.96, p ≤ 0.05), cohesiveness (r = -0.92, p ≤ 0.05), Stickiness (r = -0.76, p≤ 0.05) and oily mouth feel (r =-0.85, p≤ 0.05), but fair relation with chewiness (r = 0.65, p> 0.05) were found. The ANOVA and LSD of panel scores for each sensory attribute like appearance, taste, texture, flavor and overall acceptance showed significantly difference (p≤0.05) among treatments. From the same experiment the optimum particle size of flour i.e., 520±6µm was selected for good Sel-roti preparation. Processing parameters like soaking of rice, kneading of ingredients, ageing of batter, consistency of batter, frying temperature and time had significant effect (p≤0.05) on some physical properties and sensory quality of Sel-roti. From the same study the optimum processing parameters investigated were 2h(minimum) soaking time of rice; 10mim kneading time of ingredients for 250 g flour; 1.935DS/L corresponding velocity flow rate, 2.302cm/s or 25 ml water per 100g fresh flour; minimum 1h ageing time of batter; and 210°C(initial) frying temperature and 33S frying time. The frying medium had also effect on the quality of Sel-roti. Among the used ghee and oils refined soybean oil was selected. The result of the study of the effect of age of rice and ‘daun ‘ on the quality of Sel-roti revealed that daun is must for good Sel-roti preparation whereas age of rice had not significant effect(p>0.05). There were significant effect (p≤0.05) of ageing temperature and ageing time of batter on the biochemical parameters such as pH, acidity, reducing sugar and total sugar. On the comparison Sel-roti prepared from optimized process and recipe were found to be superior to Sel-roti prepared from traditional process. The physical properties of Sel-roti determined were 542kg/m 3, 10.78±0.55cm, and 1.93±0.16cm for bulk density, ring diameter and cross section diameter of Sel-roti respectively. The sensory properties of Sel-roti were ringed shape, light to reddish brown colour and grainy surface, moderate sweet taste, soft and little crunchy texture and sweetish and burnt sugar flavor characteristics to Sel-roti; and the proximate composition of Sel-roti were found to be as 4.68±0.10, 26.46±1.35, 0.30±.01, 0.16±0.02 and 68.41±1.44 on dry weight basis for crude protein, crude fat, ash, crude fibre and carbohydrate respectively and calorific value of Sel-roti was found to be 533kcal on dry weight basis. The texture attributes of Sel-roti were found to be 8.20±1.6, 6.01±1.4, 8.53±1.6, 7.33±1.5, 5.70±1.5, 9.47±1.6 and 15.00±3.0 for smoothness , hardness, fracturability, cohesiveness , stickiness, oily mouth feel and chewiness respectively.
Technological and Nutritional Evaluation of Sel-roti
(Faculty of Food Technology, 2013-05) Katawal, Surendra Bahadur
Sel-roti is a popular and delicious rice-based, sweet, puffed, spongy, deep-fat fried, ring shaped doughnut like Nepalese indigenous food product prepared from the batter of rice flour, ghee and sugar. Sel-roti making technology is an indigenous technology of Nepal. A survey study of 126 respondents comprising different casts, ethnicity, religion, age, sex from different district of Eastern and Central Development Regions of Nepal was conducted to gather the information on ingredients, recipe, equipments and processing methods of Sel-roti by using questionnaires. The factors affecting quality, storage and shelf life and also production, marketing, socioeconomic and cultural aspects were gathered and documented. It showed that the variety and age of rice, type of ingredients, method of preparation, and storage condition influence the quality and self-life of Sel-roti. To study the effect of particle size of rice flour on the physical properties, sensory quality and textural attributes of Sel-roti, the soaked rice was ground into flour with the help of iron mortar and pestle, analyzed for particle size distribution by using standard sieves and separated into three particle size categories i.e. coarse (>890 µm), medium (450-225 µm) and fine (<120 µm). They were mixed in different proportions; analyzed their distribution and calculated mean particle diameter; prepared Sel-roti, and analyzed for bulk density & fat uptake; and sensory and texture attributes were evaluated by trained panelists. The experiments were conducted in triplicate. The results obtained showed good positive correlation between mean particle size and the bulk density (r = 0.97, p≤ 0.05) and a good negative correlation between mean particle size and fat-uptake (r = -0.90, p≤ 0.05). Also, good correlations of mean particle size with sensory texture attributes like smoothness (r = -0.97, p≤ 0.05), hardness (r = 0.99, p≤ 0.05), fracturability (r = 0.96, p ≤ 0.05), cohesiveness (r = -0.92, p ≤ 0.05), Stickiness (r = -0.76, p≤ 0.05) and oily mouth feel (r =-0.85, p≤ 0.05), but fair relation with chewiness (r = 0.65, p> 0.05) were found. The ANOVA and LSD of panel scores for each sensory attribute like appearance, taste, texture, flavor and overall acceptance showed significantly difference (p≤0.05) among treatments. From the same experiment the optimum particle size of flour i.e., 520±6µm was selected for good Sel-roti preparation. Processing parameters like soaking of rice, kneading of ingredients, ageing of batter, consistency of batter, frying temperature and time had significant effect (p≤0.05) on some physical properties and sensory quality of Sel-roti. From the same study the optimum processing parameters investigated were 2h(minimum) soaking time of rice; 10mim kneading time of ingredients for 250 g flour; 1.935DS/L corresponding velocity flow rate, 2.302cm/s or 25 ml water per 100g fresh flour; minimum 1h ageing time of batter; and 210°C(initial) frying temperature and 33S frying time. The frying medium had also effect on the quality of Sel-roti. Among the used ghee and oils refined soybean oil was selected. The result of the study of the effect of age of rice and ‘daun ‘ on the quality of Sel-roti revealed that daun is must for good Sel-roti preparation whereas age of rice had not significant effect(p>0.05). There were significant effect (p≤0.05) of ageing temperature and ageing time of batter on the biochemical parameters such as pH, acidity, reducing sugar and total sugar. On the comparison Sel-roti prepared from optimized process and recipe were found to be superior to Sel-roti prepared from traditional process. The physical properties of Sel-roti determined were 542 kg/m3, 10.78±0.55cm, and 1.93±0.16cm for bulk density, ring diameter and cross section diameter of Sel-roti respectively. The sensory properties of Sel-roti were ringed shape, light to reddish brown colour and grainy surface, moderate sweet taste, soft and little crunchy texture and sweetish and burnt sugar flavor characteristics to Sel-roti; and the proximate composition of Sel-roti were found to be as 4.68±0.10, 26.46±1.35, 0.30±.01, 0.16±0.02 and 68.41±1.44 on dry weight basis for crude protein, crude fat, ash, crude fibre and carbohydrate respectively and calorific value of Sel-roti was found to be 533kcal on dry weight basis. The texture attributes of Sel-roti were found to be 8.20±1.6, 6.01±1.4, 8.53±1.6, 7.33±1.5, 5.70±1.5, 9.47±1.6 and 15.00±3.0 for smoothness , hardness, fracturability, cohesiveness , stickiness, oily mouth feel and chewiness respectively.
Phytochemical Screening of Ethnomedicinal Herbal Extracts and Their Effect on Microbial Quality of Sukuti
(Department of Food Technology, 2022) Rai, Sangen Ruma
The main objective of the study was to screen phytochemical constituents of ethnomedicinal herbs and to determine their effect on the microbial quality of sukuti. Specific objectives include preparation of herbal extracts, isolation, and identification of microorganisms from sukuti, determination of antimicrobial property of herbal extracts, and microbial analysis of herbal sukuti. Four ethnomedicinal herbs (Zanthoxylum armatum, Litsea cubeba, Heracleum nepalense, and Evodia fraxinifolia) having culinary importance were selected for the study. For the preparation of herbal extract, herbs were ground (particle size < 250 µ), treated with 50% ethanol (v/v), and concentrated in a rotary vacuum evaporator at 50 v o C. Four of the spoilage and pathogenic microorganism viz. Salmonella, Staphylococcus, E. coli, and Lactic acid bacteria were isolated and identified from the sukuti samples for the study. Herbal extracts at the concentration of 40, 20, 10, and 2 mg/ml were tested against the isolates to determine the antimicrobial property of the extracts. The best herb with optimum concentration was selected based on its antimicrobial activity. Zanthoxylum armatum at 40 mg/ml concentration showed the highest zone of inhibition against the test organisms and therefore selected for final product development. Meat strips (1 cm  1 cm  25 cm) were marinated with Zanthoxylum armatum (40 mg/ml) extract at the rate of 2%, aged (24 h at 4 ± 2C), and dried at cabinet drier for 2 days at 55C. Total Plate Counts of control (untreated) and herbal sukuti (treated) were carried out for 20 days within an interval of 10 days to determine the microbial stability of the final product. The total plate count for treated sample was significantly lower (p<0.05) than that of untreated sample.
Process optimization of soybean and mushroom incorporated steamed bread
(Department of Food Technology, 2022) Osti, Subash Chandra
Steamed bread was prepared with incorporation of oyster mushroom powder and defatted soybean powder, aiming to minimize wheat flour and maximize soybean and mushroom powder content in the mix. Design expert software, mixture design was used for experimental design, in which level of soybean and mushroom powder within a range from 0 to 20 parts of each for formulation of steamed bread with varying refined wheat flour content by 80 to 100 parts. Similarly, Response surface methodology, central composite design was used to design another experiment for optimization of fermentation time within a range from 30 to 90 min at 35±2°C and steaming time for 10 to 20 min at normal atmospheric condition. For microbiological study, steamed bread samples were packaged in 40 μ LDPE zip lock bags and stored at ambient and refrigerated storage conditions at 30±2ºC and 5±1ºC respectively. Both samples were subjected to microbiological assessment daily until the microbial load had reached to a critical value of 5 log cfu/g. The optimum level of wheat flour, soybean powder and mushroom powder were found to be of 87.89, 10.03 and 2.08 parts respectively with magnitude of hardness, specific volume, spread ratio and L* (whiteness) were 2801.73 g, 1.75 ml/g, 1.58 and 73.87 respectively. Fermentation time of 67.04 min at 35±2°C and steaming time of 15.05 min under normal atmospheric pressure as optimized process conditions with magnitude of hardness, specific volume, spread ratio and L* (whiteness) were 2806.63 g, 1.74 ml/g, 1.49 and 75.07 respectively. Moisture, crude fat, crude protein, total ash, crude fiber and total carbohydrate content of optimized product on dry weight basis were found to be 41.20±0.23, 2.95±0.09, 18.16±0.17, 3.98±0.11, 0.99±0.09 and 73.13±0.47% respectively. Results of sensory evaluation showed that there was no significant difference (p>0.05) between soybean and mushroom incorporated steamed bread and the control product containing 100 parts refined wheat flour in terms of color and appearance, flavor, texture, taste and overall acceptability. Microbiological analysis of steamed bread packaged in 40 μ zip lock LDPE bags showed that the product was found to be safe for consumption within the first 5 days of storage under refrigerated storage at 5±1ºC and only a day at ambient storage at 30±2ºC. The cost and calorific value of the optimized product per 100 g was found to be NRs. 12 (as of 2021) and 230.35 Kcal respectively.
Effect of Cinnamomum Verum and Zanthoxylum armatum essential oil incorporated sodium alginate edible coating on the shelf life of Panner
(Department of Food Technology, 2022) Pokhrel, Bimala
The study was carried out with objective to evaluate the effect of Cinnamomum verum and Zanthoxylum armatum essential oil incorporated Na-alginate edible coating on shelf life of paneer. Paneer samples were prepared from cow milk using citric acid (1%) as coagulant and calcium chloride at different concentrations, 0, 0.05, 0.1, 0.15, 0.2 and 0.25% (w/v) of the milk and were evaluated for composition, sensory quality and yield. The best paneer was coated with sodium alginate edible coating incorporated with 2% of Zanthoxylum armatum and Cinnamomum verum essential oils and their mix at different combinations given by the D-optimal mixture design. The control (without coating) and coated paneer samples were packed in LDPE bags (48.7 g/m 2 and 50µm thickness), stored at 7±1ºC and 52% RH, and changes on sensory attributes, chemical composition and microbial load during storage were studied at 4 days interval till 24 days. Results showed that CaCl2 at different concentrations had significant effect (p<0.05) on composition, sensory quality and yield of the paneer but not on FFA. 0.1% CaCl2 added paneer was significantly different (p<0.05) than other samples and selected as best for further coating. Storage time and edible coatings had significant effect (p<0.05) on the sensory, physicochemical (acidity, FFA, tyrosine release) and microbiological characteristics of paneer. The overall sensory scores of uncoated and single essential oil coated samples were below 6 on the 8 th days and 16 th days respectively whereas Zanthoxylum armatum and Cinnamomum verum essential oil (1.75+0.25) % coated sample remained 7 till 24 days of storage. Among all the treated samples, Zanthoxylum armatum and Cinnamomum verum essential oil mix combination (1.75+0.25) at 2% of sodium alginate coated sample was significantly different (p<0.05) in chemical characteristis (moisture content, FFA, acidity, tyrosine released) and microbial characteristics (TPC and yeast mold count).
Optimization of Humectants During Preparation of buffalo Jerky type product and its storage stability
(Department of Food Technology, 2022) Basnet, Anil
The present study optimized the concentration of different humectants in pretreatment infusion by response surface methodology. The concentration of salt, sucrose, brown sugar, maltodextrin and citric acid used were 0 to 9 g, 0 to 9 g, 0 to 3 g, 0 to 3 g, and 0 to 3 g respectively. The best-optimized sample obtained through DE® and sensory analysis was compared with the control sample (without pretreatments of humectants) concerning storage stability for 30 days in 5 days intervals at 5% level significance. From graphical and numerical optimization, the optimized combination obtained was 4 g salt, 2 g sucrose, 2 g brown sugar, 1.5 g maltodextrin, and 0.5 g citric acid giving buffalo jerky with moisture content, water activity, fat content, crude protein, ash content, pH of 10.96%, 0.63 at 20.5 ⁰ C, 4.51%, 85.47%, 8.4% and 5.62 respectively. The sensory and microbial quality of the buffalo jerky prepared from pretreated humectants mixture meat was found significantly superior to untreated (control) samples, with comparable proximate compositions. Salt concentration was more effective in reducing the water activity of the jerky than other humectants used in the present study. Crude protein content and pH were not significantly different (P>0.05) between the optimized sample and control sample whereas moisture content, fat, ash content, and water activity were significantly different (P<0.05). There was a significant difference (P<0.05) between the optimized and control samples in terms of storage stability. The optimized jerky sample was stable for 30 days at room temperature without any decrease in sensory quality and microbiological spoilage to the control jerky sample which lasted for only 20 days at room temperature.
Probiotic potentiality of lactic acid bacteria isolated from Theki Dahi around various places of Pokhara valley
(Department of Food Technology, 2022) Khanal, Pawan
This research was undertaken to study the probiotic potentiality of lactic acid bacteria (LAB) isolated from theki dahi around various places of Pokhara valley. A total of 48 samples were collected from different locations, pooled together and finally examined accordingly. Based on the morphological, biochemical and physiological characteristics, three types of Lactobacilli (LAB A, B and C), two types of Leuconostoc (LEU A and B), two types of Bifidobacterium (BIF A and B), one type of streptococci and three types of Lactococci (LCC A, B and C) were identified. Also, probiotic strain of Lactobacillus casei sub sp. Shirota was isolated from yakult sample. All the isolated microbes were then subjected to further examination for probiotic potentiality test and compared to Lactobacillus casei sub sp. Shirota. All the bacteria were found to be Gram positive, catalase-oxidase negative, non-motile bacteria, growing optimally at 30°C (expect Streptococcus thermophilus) and at 0% NaCl. In terms of acid resistance, all of them were found to be resistant to low pH 2 and 4 for 2h with a high resistance of LAB A and BIF B. Similarly, all of them were resistant to bile salt (0.3% and 0.4%) and able to hydrolyze it. Among them, LAB A and BIF B showed high resistance. With regard to antibiotic resistance, all of them were sensitive to penicillin G, ampicillin and amoxicillin but only Lactobacilli and Bifidobacterium showed resistance to ciprofloxacin. Finally, all the isolates were able to adhere to hexane. And, LAB A, BIF A and BIF B showed high hydrophobicity. This study implies that theki dahi comprises variety of LAB with probiotic properties. Statistically, in this study, LAB B and BIF A demonstrated significantly similar probiotic properties (p<0.5) to the control organism. Thus, they can be considered as potential candidate for probiotic organism in theki dahi. This research ultimately helps to document as well as commercialize theki dahi as a potential probiotic food of Nepal.
Optimization of vegetables proportion in emulsion type chicken sausage and study on its storage stability
(Department of Food Technology, 2022) Bhattarai, Tanka
This study was conducted with an objective of optimizing vegetables proportion in emulsion-type chicken sausage and evaluation of storage stability. The primary screening process was conducted in the first phase with various percentages (10, 20, 30 and 40) of vegetables (soybean, carrot and mushroom) on the basis of sensory evaluation and physicochemical properties of the prepared sausage. 30% formulation was selected from primary screening and 11 runs were generated from D-optimal mixture design. In second phase, the best percentage formulation was carried out on the basis of sensory evaluation and physicochemical properties which was then further analyzed for proximate composition, carotenoids content and antioxidant properties. The final phase of the study was carried out on storage stability of optimized sausage samples at -2°C in polyester based films (PET). Finally, optimized product was compared on the basis of sensory score with chicken sausage (control) available in Dharan sub-metropolitan. The optimized product from sensory analysis had a proximate composition, comparing 60.47, 11.89, 17.55, 0.43 and 4.17 moisture, crude fat, crude protein, crude fiber and total ash, respectively. The carotenoid content of the superior product was found to be 30 μg/ 100 g and DPPH radical scavenging activity of sausage was found to be 46.76%. There was a gradual increase in Total Plate Count (TPC) reaching maximum on day 18 (9 log/cfu) while Salmonella and coliform were not detected up to day 18. Peroxide value was also found to increase during refrigeration storage of sausage from 3.05 MeqO 2 /kg at day 0 to 11.46 MeqO 2 /kg on day 18. Vegetable-incorporated chicken sausages were successfully developed by incorporating vegetables in the formulation without any deteriorating effect on the sensory attributes and acceptability of the product. The results indicate that incorporation of vegetable in chicken based sausage like product can have the added dual benefit of improved nutritional quality and antioxidant.

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