Quality of yogurt produced from various types of milk as raw materials

Different types of milk are used to make yogurt, which gives it different qualities. Fresh milk, powdered milk, low-fat milk, non-fat milk, and Ultra High Temperature (UHT) milk all have different qualities. The goal of the study was to look at the chemical, physical, and sensory properties of yogurt made from different ingredients. The treatment’s base materials were P1: yogurt made with fresh milk, P2: yogurt made with milk powder, P3: yogurt made with ultra-high-temperature milk, P4: yogurt made with low-fat milk, and P5: yogurt made with non-fat milk. Commercial yogurt starters were used to make yogurt, and each treatment was done four times. Other tests were done with Duncan. The factors for the study are the amount of moisture, total solids, pH, total titratable acidity, and how it tastes. The results showed that the moisture content, total solids, pH, and total titratable acidity were all significantly different (P<0.05), as were the taste and preferences. The results of the study show that yogurt with different ingredients has different qualities.


Introduction
Yogurt is a fermented food that is made when lactic acid bacteria turn milk into lactic acid.Yogurt is made from various types of milk, like goat's milk [1], buffalo milk [2], and cow's milk [3].Several things, like the raw materials used and the amount of fat in the yogurt, affect its quality.Milk raw materials with a fat level of less than 0.8% have a low viscosity and a low sensory score [4].
In addition to the type of milk, yogurt can also be made from the process that turns milk into different dairy goods.The way raw materials are processed will affect the final goods, such as yogurt.Low-fat milk, non-fat milk, milk powder, and UHT milk are all made through methods that can affect the quality of the final product.The taste of yogurt and the amount of fat in the milk (3.5 and 1.5%) [5].Different physical properties are made by different types of raw materials, like powdered milk and UHT milk [6].Sensory evaluation is used to figure out how good food and research-based items are [7].
When milk is processed, various changes are made that affect the quality of the milk, especially the pH and protein levels [8].During refrigeration, UHT milk will get thicker and its pH will go down [9].Milk's physical and chemical qualities depend on how much fat it has [10].How yogurt is made depends on the quality of the ingredients.The amount of total carbohydrates, protein, lactose, and acidity in the milk will affect how it ferments and what it is made of [4,11].
There have been many studies comparing the quality of yoghurt made from different types of milk.However, the comparison of the quality of yoghurt made from full-fat, low-fat and non-fat UHT milk is still very limited.The type of milk used to make the yogurt changes the pH, the amount of lactic acid, and the number of microbes in the yogurt.UHT milk yogurt raw materials have the best pH value, amount of lactic acid, and number of bacteria.The objective of this study was to investigate the effects 2 of the type of milk used to make yogurt affects its taste and quality [12].The result of this research may contribute to the development of specialty yogurt that meet the demand of different customers.

Materials and methods
No ethical clearance was issued for these experiments since animals were not treated directly.The yogurt used in the study was made from raw milk (full fat), UHT milk, powdered milk, low-fat milk, and nonfat milk.A prepared yogurt starter is used for the starter.For each batch, 1 liter of raw materials and 5% starting are needed.

Yogurt production
The first stage begins with heating the milk raw materials.HTST pasteurization of fresh milk.UHT milk, low-fat milk, and non-fat milk were all heated to 45 o C. Powdered milk was dissolved in warm water.This method is used to make yogurt [13].For each treatment, 5% of a commercial dry starter was added and it was kept at 37 o C for 5 hours.Indicators of yogurt are a sour taste and a thick texture.The yogurt is then kept in a cold place (the refrigerator) for 6 hours before different measures are taken.2006) used an oven and the gravimetric method to determine the amount of total solids and moisture in yogurt [14].

The pH of yogurt
Using a pH meter (AMT 16), the pH value was used as a measure of acidity.Before measuring, the pH was calibrated (between 4.0 and 7.0).The sample of yogurt was put in 20 ml of a Becker glass.The pH meter was then put in the glass and left for a few minutes until a stable number was reached [15].

Total titratable acidity
Total titratable acidity made during the fermentation of yogurt is used to figure out how much total production of organic acid there is.The formula [16] is presented below.

Sensory test
Sensory tests were done to find out how panelists liked yogurt made from different raw materials.The test subjects were 20 semi-trained panelists who looked at 5 samples of yogurt.Yogurt attributes assessed include taste, aroma, texture, and overall preference.Hedonic testing is done by giving a score of 1 to 5.

Data analysis
The data were put through statistical analysis, and each treatment was done four times, after which Duncan used the SPPS version 25 to compare the results.

Results and discussion
The basic quality of yogurt can be affected by the types of raw materials that are used to make it.The raw materials, starter, milk composition, temperature, processing, addition of prebiotics and probiotics, and packing materials all affect the quality of yogurt [17].Yogurt tastes fresh and sour, and it has a fairly thick texture.Its main molecule comes from lactic acid.Table 1 shows the chemical properties of yogurt made with various types of milk.Table 1 shows that yogurt made from non-fat milk has the most moisture and the least amount of total solids.With yogurt made from full-fat milk, these results were very clear (P<0.01).The total solids of yogurt are affected by the amount of fat in the raw materials.Yogurt with no fat has a smaller total solids, but other things affect yogurt as well.If you cut down on the fat in yogurt, the overall solids will go down, and the taste, texture, low viscosity, and bad taste will change [18].It is used to make non-fat milk and is mostly made up of protein [19].The low amount of total grains will make the yogurt contain more moisture, which will make the yogurt less thick.Whatever types of raw materials are used to make yogurt, the pH number stays the same.The pH of yogurt can be anywhere between 4.05 and 4.59.The churning process and the type of yogurt affect the pH value of yogurt.In general, yogurt has a pH range of 3.97-4.59.The pH of commercial yogurt is between 4.08 and 4.35 [20].When different ingredients are used to make yogurt, the titrable acidity value ranges from 0.79 to 1.20.The amount of lactic acid titrated with NaOH shows how acidic something is.The amount of fat, which is part of the total solids, changes the TTA number [18].The largest TTA is found in low-fat and fat-free yogurt.The results show that the TTA of low-fat and fatfree yogurt is higher than that of full-fat milk.When yogurt is made from various types of milk, the way it tastes will change.Table 2 shows how yogurt made from various types of milk tastes and feels.The range of preference scores for the smell of yogurt is 2.40 to 3.85 (dislike-like).The highest preference score is for yogurt made from UHT milk, which is significantly different (P<0.01)from yogurt made from non-fat milk.The texture preference score ranges from 1.60 to 4.40 (dislike-like), with the best score coming from yogurt made with UHT milk.The results are very different from all the other treatments.The taste of the yogurt made got a score of 2.00 to 3.00 (dislike to rather liked) and was different between yogurt made from full-fat milk and yogurt made from non-fat milk (P<0.05).Overall, yogurt made from UHT milk is the most liked, with a score of 3.65 (likes) being the best.Panelists prefer the smell, taste, texture, and aftertaste of yogurt made with UHT milk compared to yogurt made with pasteurized milk [21].

Table 1 .
Yogurt chemical characteristics with differences in raw materials Note: Different superscripts in the same column are significantly different (P<0.05).ns: not significantly different; *: significantly different; **: highly significant different.

Table 2 .
Sensory characteristics of yogurt with different raw materials *: significantly different; **: highly significant different.