Effect of Different Milk Composition on Physico-Chemical Characteristics of Set Type Yoghurt

Muhammad Asif Iftikhar1, Talat Naseer Pasha2, Saima Inayat1, Khalid Javed3 and Rahman Ullah4*

1Department of Dairy Technology, University of Veterinary and Animal Sciences, Lahore, Pakistan

2Department of Animal Nutrition, University of Veterinary and Animal Sciences, Lahore, Pakistan

3Department of Livestock Production, University of Veterinary and Animal Sciences, Lahore, Pakistan

4Faculty of Veterinary and Animal Sciences, The University of Agriculture, Dera Ismail Khan, Pakistan

ABSTRACT

The gross composition of milk may affect the textural, compositional and microbiological properties of yoghurt. Sahiwal, Holstein Friesian milk procured from Dairy Animal Training and Research Center, B-block University of Veterinary and Animal Sciences, Pattoki and Nili Ravi buffalo milk procured from Nili Ravi buffalo Research Institute (BRI), Pattoki. All other ingredients purchased from Sigma Aldrich Germany through local suppliers. Milk was standardized to 15% total solids with 3.5% fat. Skim Milk Powder (SMP) was used for the standardization of the yogurt. Milk was pasteurized at 82oC for 5 minutes and cool down to 43oC and at this temperature starter culture was added. Yogurt batch incubated at 43oC for 3 to 3.5 h. During this period pH was monitored regularly and as the pH drops to 4.6, the batch was shifted to blast chilling at 1-2oC and then stored at 4oC. Sensory evaluation of all yogurt samples was carried out on a 9-point hedonic scale. All the tests were carried out on day 0, 7, 14 and 21. The collected data was investigated through ANOVA technique under complete randomized design (CRD) using SAS 9.1 software. The results showed that yoghurt made from Nili Ravi buffalo milk (To) showed a significant (p≥ 0.5) overall acceptability as compared to other treatments. Yoghurt made from Nili Ravi buffalo milk (To) were followed by T3, T4, T1 and T5 respectively. The Nili Ravi buffalo milk showed higher acceptability to the consumers.

Article Information

Received 04 August 2022

Revised 25 October 2022

Accepted 18 November 2022

Available online 23 February 2023

(early access)

Published 17 April 2024

Authors’ Contribution

MAI and TNP planned, designed and carried out the study while KJ, SI and RU analyzed the data and put the study in present form.

Key words

Yoghurt, Different milk composition, Breeds, Physiological characteristics, Set yoghurt

DOI: https://dx.doi.org/10.17582/journal.pjz/20220804100820

* Corresponding author: rahmanmohmand99@yahoo.com

0030-9923/2024/0003-1297 $ 9.00/0

Copyright 2024 by the authors. Licensee Zoological Society of Pakistan.

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

INTRODUCTION

Pakistan is the 4th largest milk producing country in the globe; most of the milk is produced by cattle and Nili Ravi buffaloes, with some contribution from other milk breeds as well. Milk production in Pakistan has been increased by more than 40% in the last 10 years with a total production of 54,328 thousand tons. The Nili Ravi buffalo milk and cow milk contribution in the total milk production in Pakistan is 60.9% and 35.7%, respectively (GOP, 2018-19). Despite of gradual increase in demand of milk and milk products the dairying community of Pakistan is facing multiple problems. Globally, surplus milk is converted into numerous value-added products, but only few of these milk products are prepared in Pakistan.

Nili Ravi buffalo contributes approximately 60% of the total milk produced in Pakistan (GOP, 2018-19). The main reasons for popularity of Nili Ravi buffalo milk is due to its higher fat content (~6.5%) as well as solids-not-fat (~10.5%). The local culture of making Lassi, tea and dahi using Nili Ravi buffalo milk renders it a good choice. Nili Ravi buffalo milk is particularly rich in vitamin A and lacks in carotene. This is the reason of whiter color of Nili Ravi buffalo milk as compared to cattle milk. Nili Ravi buffalo milk is highly suitable for the manufacturing of large number of value-added dairy products including fermented milk products such as yoghurt, lassi and cheese (Moioli et al., 2006). In current industrial process of procuring the fermented products, cow milk is predominant world-wide. Variety of fermented milk products including fruit, flavored, plain yoghurt, whipped, drinking type, smoked, dried, strained and frozen products are prepared from cow milk globally. The total solids contents of cow milk are less than Nili Ravi buffalo milk therefore to have proper curd consistency of fermented products, cow’s milk is generally fortified with skim milk powder (White et al., 2008).

Fermented milk products that are made from various milk sources, originated in the Middle East, perhaps before the Phoenician era, and spread throughout Europe. Human diet could be supplemented with fermented dairy products that can eventually provide essential nutrients vital for growth and better health (Serhan et al., 2016). Haj et al. (2007) reported that acidifying the milk through fermentation is the oldest methods of preservation of milk. Fermentation can be attained through chemical and microbiological methods. The variation in fermentation processes results in the production of various fermented dairy products such as keifr, kumiss, acidophilus milk, yoghurt etc.

Yogurt is a coagulated milk, mostly obtained by the action of two bacteria, which are Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus (Trachoo, 2002). Yogurt is made of milk, considered as a complete food. It is mostly consumed by infants or elder people. It contains all nutrition required by the people, along with this also contain live microbes (Ayar et al., 2006).

Yoghurt having health benefits like enhancing lactose digestion by maldigesters, protection against gastrointestinal upsets, lowering the risk of cancer, improving immune response, decreasing the blood cholesterol, calcium and iron, helping the body to assimilate protein, diarrhoea protection, longevity and control. It also helps in maintenance of GIT (gastrointestinal) microflora as well (Andronoiu et al., 2011; Vahedi et al., 2008; Iwalokun and Shittu, 2007; Foda et al., 2007; Aly et al., 2004). Other health benefits of yoghurt include improvement in the bowel movement, enhancement of GIT (gastrointestinal) function, consumption of different constituents in the GIT. These are most likely due to the action of gut microflora and also improving immune response (Adolfsson et al., 2004). Consumers (children, young and aged person) mostly demand novel product with the formulation of nutrition in plain yoghurt.

MATERIALS AND METHODS

Experimental site

The research was carried out in postgraduate laboratory of Department of Dairy Technology and Central Laboratory Complex (CLC), Ravi campus, University of Veterinary and Animal Sciences, Pattoki, District Kasur, Pakistan.

Procurement of milk

Sahiwal, Holstein Friesian (HF) milk was procured from Dairy Animal Training and Research Center, B-block University of Veterinary and Animal Sciences, Pattoki and Nili Ravi Nili Ravi buffalo milk procured from Buffalo Research Institute (BRI), Pattoki. All other ingredients were purchased from Sigma Aldrich Germany through local suppliers. The experiment and analysis of the samples were carried out in the Department of Dairy Technology and CLC, A-Block, University of Veterinary and Animal Sciences, Pattoki.

Procurement of ingredients

Starter culture, Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus, was purchased from Danisco, Sweden through local suppliers. All other ingredients (stabilizers) were procured from local market, Lahore.

Preparation of starter culture

The freeze-dried culture was propagated by inoculation into fresh milk which was heated at 90°C for 3 minutes. The inoculated milk incubated at 45°C until pH 4.6 is reached and then Stored overnight at 4°C.

Preparation of yogurt

Standardized milk was used having 15% total solids and 3.5% fat. Skim Milk Powder (SMP) was used for the standardization of the yogurt. Milk was pasteurized at 82oC for 5 minutes and cool down to 43oC and at this temperature starter culture was added. Yogurt batch incubated at 43oC for 3 to 3.5 h. During this period pH was monitored regularly and as the pH drops to 4.6, the batch was shifted to blast chilling at 1-2oC and then stored at 4oC.

Experimental design

A total of 6 treatments were prepared and 100% Nili Ravi buffalo milk yogurt was used as control (To). T1 was prepared from Sahiwal milk (100%), T2 was prepared from 100% Holstein Friesian milk, T3 was prepared from 50% Nili Ravi and 50% Sahiwal milk, T4 was prepared from 50% Nili Ravi and 50% Holstein Friesian milk while T5 was prepared from 50% Sahiwal and 50% Holstein Friesian milk. Yogurt was stored at 4oC for three weeks and analyzed at day 0, 7, 14 and 21.

Physico-chemical determination

Physico-chemical characteristics of all the treatments were carried out for protein, total solids, fat content, pH and titratable acidity according to the standard methods of Association of Analytical Chemists (AOAC, 1999).

Textural properties

Textural properties of all the treatments were determined for the following parameters.

Gel firmness

Gel firmness of yogurt was determined at 4-6ºC by penetration measurements (Texture Analyzer, LFRA-4500, Brookfield, Inc., USA) equipped with a 4.5 kg load cell. The apparatus was adjusted to the following conditions: cylindrical probe (38mm in diameter); penetration speed 1mm/s; penetration distance 30mm into surface. The peak force measured in grams (Aly et al., 2004).

Monitoring of viscosity during yogurt manufacturing

Yogurt viscosity was measured by using Brookfield viscometer model BM type. Three readings from every sample taken and an average value was recorded. The readings taken at 10ºC, which is the temperature at which the yogurt is most likely to be consumed. The spindle speed adjusted keeping in view to the thickness level of the sampled yogurt. In this experiment, the standard combination used, speed 12 (revolutions/second) and spindle number 4. To calculate the final viscosity in centipoises, a factor of 500 is taken to multiply the obtained figure.

Monitoring of pH during yogurt manufacturing

The milk pH during the process of gelatin was recorded on regular basis by immersing the glass electrode of the pH meter (H19020 microprocessor bench pH meter; Hanna Instruments, Woonsocket, RI, USA) in the milk. The pH meter standardized with buffers at 45°C before use.

Syneresis

Syneresis measured according to the method described by Aly et al., (2004). Yogurt mix (25g) weighed in a centrifuge tube and the samples was then be reared together and the set gels were then be stored at 4ºC for 24 h. Samples of yogurt weighed and centrifuged for 10 min at 3500xg and at 4ºC. The whey extracted from the sample of yogurt de-caned off and the rest of the yogurt reweighed. The WHC is defined as weight (g) of the remaining (or drained) yogurt out of the total weight (100g) of the yogurt (before centrifugation).

Water holding capacity

The water-holding capacity of yogurt was determined according to the technique recommended by Aly et al. (2004). 20g of a sample of yogurt (Y) centrifuged at 1250 x g for 10 min at 4°C. The whey that is extracted (W) removed and weighed. The water-holding capacity (WHC, g.kg−1) calculated as:

WHC = (Y – W) /Y x 1000

Sensory evaluation

Sensory evaluation of all yogurt samples was carried out on a 9-point hedonic scale by a panel of 10 semi trained judges. Sensory evaluation was carried out on day 0, 7, 14 and 21.

Statistical analysis

The collected data under investigation was analyzed through ANOVA technique under complete randomized design (CRD) using SAS 9.1 software. Duncan multiple range (DMR) test applied to find the difference between means. The data obtained in triplicates and each treatment was also triplicated.

RESULTS

Physico-chemical properties

Highest protein, total solids (TS) and fat content were recorded at day 1st and gradual reduction was observed with the passage of storage period as shown in Table I. The maximum protein (p<0.001) contents were obtained in 1st day and the least in 21st day. Fat and protein largely affected by microbes. During storage fat and protein decreases as microbial action increases. Table II shows pH and acidity of yoghurt at different storage days prepared from different milk sources.

Textural properties

The microstructure and the rheological properties of set yogurts are considerably critical to product quality and shelf life. Syneresis, serum release from the gel matrix, is regarded as a technological defect in set yogurts. Serum release, known as syneresis, is considered as one of the most important parameters indicating the quality of yogurt during storage. Gel firmness, viscosity, syneresis and water holding capacity of yoghurt at different storage days prepared from different sources of milk are shown in Table III. The results showed that gel firmness increases with storage period and highest firmness was observed in at day 21 of storage period in all the treatments. It was also observed that Highest firmness was observed in T0 (100%) Nili Ravi buffalo milk followed by T1 and T5.

 

Table I. Protein (%) total solids (%) and fat (%) of yoghurt at different storage days prepared from different milk sources.

Treatments*	Parameters	Storage days
		1st	7th	14th	21st
T0	Proteins	3.90±0.19a	3.85±0.14a	3.78±0.08a	3.70±0.09a
	Total solids	15.00±0.15a	13.80±0.16d	13.72±0.15e	13.68±0.18d
	Fats	3.50±0.16a	3.47±0.18b	3.32±0.16c	3.24±0.19d
T1	Proteins	3.20±0.14c	3.16±0.16c	3.12±0.05c	3.07±0.06d
	Total solids	15.00±0.29a	14.70±0.26b	14.55±0.25d	14.20±0.28c
	Fats	3.50±0.19a	3.46±0.17b	3.35±0.15c	3.39±0.16d
T2	Proteins	2.70±0.18f	2.67±0.18f	2.64±0.06f	2.60±0.07f
	Total solids	15.00±0.19a	14.72±0.16b	14.50±0.18d	14.18±0.16c
	Fats	15.00±0.19a	14.72±0.16b	14.50±0.18d	14.18±0.16c
T3	Proteins	3.50±0.15b	3.46±0.15b	3.42±0.07b	3.40±0.08b
	Total solids	15.00±0.20a	13.90±0.24b	13.73±0.05d	13.55±0.05d
	Fats	3.50±0.27a	3.44±0.28b	3.39±0.26c	3.35±0.28d
T4	Proteins	3.30±0.17c	3.26±0.14c	3.23±0.08c	3.20±0.06c
	Total solids	15.00±0.05a	13.95±0.05b	13.82±0.23d	13.67±0.25e
	Fats	3.50±0.15a	3.43±0.13b	3.34±0.09c	3.31±0.08d
T5	Proteins	2.90±0.18e	2.87±0.17e	2.84±0.07e	2.80±0.05e
	Total solids	15.00±0.18a	14.73±0.17b	14.45±0.15c	14.05±0.16f
	Fats	3.50±0.15a	3.42±0.14b	3.36±0.14c	3.29±0.11d

 

Within rows and columns, means denoted by a different letter are statistically different (p<0.05). *For treatments details please see section under the heading experimental design.

 

Table II. pH and acidity of yoghurt at different storage days prepared from different milk sources.

Treatments*	Parameter	Storage days
		1st	7th	14th	21st
T0	pH	4.60±0.19a	4.51±0.16a	4.38±0.18b	4.24±0.19c
	Acidity	0.89±0.18a	0.92±0.17a	0.95±0.19a	0.98±0.16b
T1	pH	4.60±0.18a	4.48±0.17a	4.32±0.19b	4.21±0.14c
	Acidity	0.85±0.09a	0.88±0.08a	0.91±0.07a	0.95±0.08b
T2	pH	4.60±0.27a	4.49±0.27a	4.41±0.23b	4.35±0.22c
	Acidity	0.88±0.08a	0.92±0.09a	0.94±0.05a	0.96±0.05b
T3	pH	4.60±0.18a	4.47±0.17a	4.38±0.17b	4.32±0.12c
	Acidity	0.88±0.09a	0.93±0.07a	0.95±0.09a	0.97±0.06b
T4	pH	4.60±0.06a	4.49±0.05a	4.37±0.05b	4.31±0.09c
	Acidity	0.86±0.05a	0.88±0.07a	0.90±0.08a	0.94±0.07b
T5	pH	4.60±0.30a	4.50±0.24a	4.37±0.22b	4.30±0.25c
	Acidity	0.87±0.04a	0.90±0.04a	0.93±0.05a	0.97±0.08b

 

Rows and columns with the same letter having non-significant difference. * For treatments details please see section under the heading experimental design.

 

Table III. Gel firmness, viscosity, syneresis and water holding capacity (WHC) of yoghurt at different storage days prepared from different milk sources.

Treatments*	Parameters	Storage days
		1st	7th	14th	21st
T0	Gel firmness	72.00±0.29a	70.00±0.32a	69.00±0.30a	65.00±0.32b
	Viscosity	4342.00±0.38a	4330.00±0.38a	6230.00±0.33a	4900.00±0.35b
	Syneresis	35.00±0.28d	37.00±0.26c	37.00±0.25c	39.00±0.27d
	WHC	60.00±0.26a	58.90±0.25a	58.69±0.27a	58.86±0.27b
T1	Gel firmness	69.00±0.29a	67.50±0.28a	66.00±0.28b	62.00±0.29d
	Viscosity	3921.00±0.36a	3955.00±0.37a	5380.00±0.34a	4233.00±0.33c
	Syneresis	36.50±0.26c	38.50±0.28b	37.00±0.29c	35.50±0.23e
	WHC	57.50±0.23c	56.95±0.22c	56.35±0.26c	55.43±0.21c
T2	Gel firmness	64.00±0.28b	62.50±0.25b	60.50±0.27c	57.00±0.25e
	Viscosity	3350.00±0.35a	3356.50±0.36a	4430.00±0.37a	4155.00±0.36d
	Syneresis	39.00±0.28b	41.50±0.24a	43.00±0.27a	42.50±0.29b
	WHC	52.50±0.21d	51.00±0.28d	51.50±0.25d	51.00±0.26e
T3	Gel firmness	66.00±0.32b	65.00±0.31b	63.00±0.33d	59.00±0.35c
	Viscosity	3500.00±0.35a	3480.00±0.36a	4530.00±0.38a	3966.00±0.32e
	Syneresis	38.00±0.26b	40.11±0.21a	42.00±0.26a	41.00±0.27b
	WHC	55.00±0.24c	54.00±0.25c	53.00±0.26c	52.00±0.25d
T4	Gel firmness	62.00±0.29c	60.00±0.28c	58.00±0.24e	55.00±0.26f
	Viscosity	3200.00±0.29a	3133.00±0.34a	4330.00±0.36a	3544.00±0.38f
	Syneresis	40.00±0.29a	40.19±0.27a	42.00±0.26a	44.00±0.23a
	WHC	50.00±0.28e	49.77±0.24e	48.66±0.27e	46.00±0.26f
T5	Gel firmness	67.00±0.12b	65.00±0.15b	63.50±0.18d	60.00±0.17c
	Viscosity	3771.00±0.35a	3631.50±0.37a	5280.00±0.31a	3422.00±0.36g
	Syneresis	37.50±0.27c	40.00±0.26a	38.00±0.24b	37.00±0.25c
	WHC	55.00±0.23c	51.95±0.22d	48.85±0.26e	40.43±0.25f

 

Rows and Columns with the same letter having non-significant difference. * For treatments details please see section under the heading experimental design.

 

Sensory properties

Sensory properties such as appearance, texture, taste, smell are shown in Table IV. Table V shows the overall acceptability of different milk sources.

DISCUSSION

Physico-chemical properties

Reduction in protein may be due to proteolysis activity as lactic acid bacteria hydrolyze milk protein and produces amino groups (Unal and Akalin, 2012). These results are in line with literature, lactose converted into galactose to glucose and decreasing lactose contents, so TS was decreased in all the treatments with storage period. Another study showed that some amino groups make interaction with lactose so same trend was observed in decreasing TS contents. Ca, P and Mg decreased as storage period increased.

Acidity decreases towards the storage period as shown in Tables III and V. It may be due to the microbial action. As Streptococcus thermophilus and Lactobacillus bulgaricus are the major source of decreasing acidity and conversion of lactose to lactic acid as well. She said that there was slight increase in the acidity of yoghurt during storage period. Acidity decreases from 0.9 to 1.7% during the storage of commercial yoghurt. This was due to the microbial action and non-availability of blast chiller room. They reported that there was not storage effect on TS and SNF of yoghurt, and these values decreased as storage period prolongs. This might be due to the relation between lactose, amino acid and other components. This all happens due the microbial action and different chemical reactions.

 

Table IV. Appearance, texture, taste and smell of yoghurt at different storage days prepared from different milk sources.

Treatments*	Parameters	Storage days
		1st	7th	14th	21st
T0	Appearance	8.37±0.33a	8.33±0.33a	7.99±0.17a	7.33±0.33b
	Texture	8.50±0.29a	8.42±0.30a	8.17±0.17a	7.80±0.33b
	Taste	8.67±0.33a	8.33±0.33a	8.25±0.17a	7.92±0.33b
	Smell	7.50±0.29	7.83±0.44	8.00±0.35	8.50±0.29
T1	Appearance	8.17±0.23a	7.83±0.33a	8.16±0.08a	7.00±0.29b
	Texture	8.17±0.22a	8.04±0.29a	7.83±0.22a	7.55±0.33c
	Taste	8.25±0.25a	7.92±0.30a	7.88±0.18a	7.66±0.25b
	Smell	7.17±0.36	7.58±0.36	7.58±0.08	8.21±0.18
T2	Appearance	8.13±0.29a	7.83±0.33a	7.95±0.17a	6.33±0.44d
	Texture	7.58±0.17b	7.42±0.22b	7.40±0.36b	7.29±0.33e
	Taste	7.50±0.14d	7.38±0.22d	7.44±0.19d	7.10±0.23e
	Smell	6.50±0.52	7.17±0.30	6.96±0.21	7.63±0.13
T3	Appearance	8.10±0.26a	7.95±0.33a	8.02±0.00a	6.67±0.33c
	Texture	7.83±0.17b	7.67±0.33b	7.62±0.29b	7.44±0.33d
	Taste	7.83±0.17c	7.50±0.29c	7.45±0.25c	6.67±0.17f
	Smell	6.83±0.44	7.33±0.33	7.17±0.17	7.92±0.08
T4	Appearance	8.24±0.36a	8.05±0.33a	8.06±0.33a	6.00±0.58e
	Texture	7.33±0.17b	7.17±0.17b	7.15±0.44b	7.05±0.33f
	Taste	7.17±0.17e	7.25±0.14e	7.21±0.14e	6.42±0.30g
	Smell	6.17±0.60	7.00±0.29	6.75±0.25	7.33±0.17
T5	Appearance	8.22±0.31a	8.12±0.33a	8.08±0.08a	6.67±0.44c
	Texture	7.92±0.22b	7.79±0.15b	7.75±0.29b	7.41±0.33d
	Taste	7.92±0.22b	7.79±0.23b	7.69±0.15b	6.38±0.31g
	Smell	6.83±0.44	7.42±0.30	7.38±0.13	7.92±0.22

 

Rows and Columns with the same letter having non-significant difference. * For treatments details please see section under the heading experimental design.

 

Textural properties

Undoubtedly, the tendency to exhibit syneresis also depends on the changing in pH, which affects the gel structure, which is a casein micelle network containing heat-denatured whey proteins bound to the surface of the casein micellesIn milk, the integrity of casein micelles is controlled by a localized balance between hydrophobic interaction and electrostatic repulsion (Horne, 1998; Lucey, 2002). As the pH of milk decreases during fermentation, the CCP within casein micelles is solubilized, especially at pH<6.0, and it is completed by pH~5.0, which leads to the partial rearrangement of the internal structure of casein micelle (Lucey, 2002). As the pH of milk approaches the isoelectric point (i.e., pH< 5.0), electrostatic repulsion decreases, which facilitates enhanced casein–casein attractions due to increased hydrophobic interactions. These factors increase bond formation/strength and thus increase gel stiffness. Continuing to grow the lactic acid bacteria and also to produce lactic acid through the storage is responsible for the reduction in the pH.

Viscosity of the yoghurt increased with storage period in all the treatments and highest viscosity was observed in To followed by T1 and T5. The viscosity may be related with gel firmness. Syneresis of the samples and control is shown in Table III. It is evident that syneresis increased with the passage of time in all the treatments including control. In Table III, it is shown that water holding capacity was decreased up to storage period of 14 days and decreased on 21 days. Highest water holding capacity was observed in T0 followed by T1 and T5. As considered by many researchers syneresis is one of the most important parameters indicating the quality of yogurt during storage and consumer satisfaction (Shakerian et al., 2015).

Sensory properties

Appearance of yoghurt is increased with storage period in all the treatments. Appearance of yoghurt made from 100% Nili Ravi buffalo milk was higher throughout the storage period as compared to other treatments followed by T1 and T5, respectively. Similarly, texture was also increased with the passage of storage in all the treatments. Higher texture was observed in T1 and T5, respectively. Score for smell was also found increased in all the treatments throughout storage period in all the treatments. Highest score was found in To followed by T1 and T5. Overall acceptability is shown in Table V which shows that overall acceptability of yoghurt made from different combination of milk sources was found increased with the passage of storage period. Overall acceptability of To was higher followed by T1 and T5.

 

Table V. Overall acceptability of yoghurt at different storage days prepared from different milk sources.

Treatments*	Storage days
	1st	7th	14th	21st
T0	8.61±0.31a	8.36±0.22a	7.61±0.15b	7.33±0.33c
T1	8.20±0.26a	7.93±0.24b	7.27±0.13c	6.94±0.28e
T2	7.42±0.21c	7.21±0.23c	6.61±0.10e	6.07±0.32g
T3	7.78±0.22b	7.50±0.25d	6.92±0.13e	6.56±0.24f
T4	7.06±0.20d	6.92±0.21e	6.31±0.07f	5.58±0.39h
T5	7.83±0.26b	7.64±0.20b	6.96±0.11e	6.46±0.36f

 

Rows and Columns with the same letter having non-significant difference. * For treatments details please see section under the heading experimental design.

 

CONCLUSION

Yoghurt made from different sources of milk showed that using 100% Nili Ravi buffalo milk has good physico-chemical, textural and sensory properties as compared to yoghurt made from other sources of milk or mixed milk. The results in comparison shows that highest score was observed in To (100% Nili Ravi buffalo milk) followed by T3 (50% Nili Ravi buffalo and 50% Sahiwal Cow milk), T4 (50:50 of Nili Ravi buffalo and Friesian), T1 (100% Sahiwal milk), T5 (50:50 of Sahiwal and Friesian) and T2 respectively. Blends of cow and Nili Ravi buffalo milk have also good effects on overall performances and result of yoghurt.

ACKNOWLEDGEMENT

The authors acknowledge and thanks all the supporting staff of Department of Dairy Technology, University of Veterinary and Animal Sciences, Lahore for their help in collection of data and providing assistance during lab analysis.

Funding information

The authors did not receive any funding from any sources regarding current research work.

Ethical certificate

As no animal were used or trialed for this research work, so ethical certificate was not applicable.

Statement of conflict of interest

The authors have declared no conflict of interest.

REFERENCEs

Adolfsson, O., Meydani, S.N., and Ru, R.M., 2004. Yogurt and gut function. Am. J. Clin. Nutr., 80: 245-256. https://doi.org/10.1093/ajcn/80.2.245

Aly, A.S., Galal, E.A., and Elewa, A.N., 2004. Carrot yoghurt: Sensory, chemical, microbiological properties and consumer acceptance. Pak. J. Nutr., 3: 322-330. https://doi.org/10.3923/pjn.2004.322.330

Andronoiu, D.G., Botez, E., Mocanu, G.D., Nistor, O., and Nichiforescu, A., 2011. J. Agroaliment. Proc. Technol., 17: 452-455.

AOAC, 1999. Official methods of analysis of AOAC international, 16th Ed., 5th Rev., AOAC International, Gaithersburg, MD.

Ayar, A., Sert, D., Kalyoncu, I., and Yazici, F., 2006. Physical, chemical, nutritional and organoleptic characteristics of fruit added yogurts. J. Fd. Technol., 4: 44-49.

Foda, M.I., El-Aziz, M.A., and Awad, A., 2007. Chemical, rheological and sensory evaluation of yoghurt supplemented with turmeric. Int. J. Dairy Sci., 2: 252-259. https://doi.org/10.3923/ijds.2007.252.259

GOP, 2018-19. Government of Pakistan, Economic Advisor’s Wing, Finance Division, Islamabad. pp. 18-19.

Haj, M.H., El-Owni, O.A., and El-Zubeir, I.E., 2007. Assessment of chemical and microbiological quality of stirred yoghurt in Khartoum State, Sudan. Res. Vet. Sci., 2: 56-60.

Horne, D.S., 1998. Casein interactions: Casting light on the Black Boxes, the structure in dairy products. Int. Dairy J., 8: 171-177. https://doi.org/10.1016/S0958-6946(98)00040-5

Iwalokun, B., and Shittu, M., 2007. Effect of Hibiscus sabdariffa (calyce) extract on biochemical and organoleptic properties of yogurt. Pak. J. Nutr., 6: 172-182. https://doi.org/10.3923/pjn.2007.172.182

Lucey, J.A., 2002. Formation and physical properties of milk protein gels. J. Dairy Sci., 85: 281-294. https://doi.org/10.3168/jds.S0022-0302(02)74078-2

Moioli, B., Coletta, A., Fioretti, M., and Khan, M.S., 2006. Genetic improvement of dairy buffalo: Constraints and perspectives. 8th World Congress on Genetics Applied to Livestock Production. Belo Horizonte, MG, Brazil.

Serhan, M., Mattar, J., and Debs, L., 2016. Concentrated yogurt (Labneh) made of a mixture of goats’ and cows’ milk: Physicochemical, microbiological and sensory analysis. Small Ruminant Res., 138: 46-52. https://doi.org/10.1016/j.smallrumres.2016.04.003

Shakerian, M., Razavi, S.H., Ziai, S.A., Khodaiyan, F., Yarmand, M.S., and Moayedi, A., 2015. Proteolytic and ACE-inhibitory activities of probiotic yogurt containing non-viable bacteria as affected by different levels of fat, inulin and starter culture. J. Fd. Sci. Technol., 52: 2428-2433. https://doi.org/10.1007/s13197-013-1202-9

Trachoo, N., 2002. Yogurt: The fermented milk. Songklanakarin. J. Sci. Technol., 24: 726-736.

Unal, G., and Akalm, A.S., 2012. Antiosidant ad angiotensin-covering enzyme inhibitory activity of yoghurt fortified with sodium calcium caseinate or whey protein concentrate. Dairy Sci. Technol., 92: 627-639. https://doi.org/10.1007/s13594-012-0082-5

Vahedi, N., Tehrani, M.M., and Shahidi, F., 2008. Optimizing of fruit yoghurt formulation and evaluating its quality during storage. Am. Euras. J. Agric. Environ. Sci., 3: 922-927.

White, C.H., and Arun-Kilara, Y.H., 2008. Manufacturing yogurt and fermented milks (ed. R.C. Chandan). John Wiley and Sons. pp. 3-8.