Food Technology

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

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Browsing Food Technology by TU Institute "Central Campus of Technology, Dharan"

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    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.
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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 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.