with the collaboration of Iranian Food Science and Technology Association (IFSTA)

Document Type : Full Research Paper

Authors

1 Department of Food Sciences and Technology, Expert of Iran Dairy Industries Co.,(Pegah) , Kerman, Iran.

2 Department of Food Science and Technology, Ferdowsi University of Mashhad, Iran.

Abstract

Introduction: Doogh is one of the most important and most widely consuming fermented traditional Iranian milk products, which is being prepared from the healthy milk by using the activity of certain lactic acid bacteria and molds under the especial conditions. Streptococcus thermophilus and Lactobacillus bulgaricus are used as starter culture for milk fermentation. The fermented dairy products have long storage life and constitute an important part of the milk's per capita consumption. For this reason, studying the different methods in order to improve the quality of these products is crucial. By considering the fact that the strong thermal treatments damage some components of milk such as protein and vitamins, using the membrane filterations decrease the need to impose the intense thermal conditions which result into the relative loss of nutrients. On the other hand, using the membrane filters not only increase SNF (solid non-fat) and the percentage of protein but also lead into the production of less-lactose milk as well, the production of less-lactose products, in addition to their nutritional value for some people, have especial benefits for improving the quality. As follows, UF filters in 10-2-10-1 diameter separate the bacteria, fats and protein when milk is passing with a pressure about 1-10 bar but also they pass the minerals such as salts and water which are being removed as permeate and the concentrated milk is called “Retentate”.
 
Materials and methods: Materials provided in this study were including: Starter culture (No: 505 form Danisco, USA), Lactic acid (1.00366) with a degree of purity level more than 95%, NaH2PO4*2H2O (1.06345) plus the cultures' environment and the chemical substances from MERCK Company. HPLC system (Agilent, 1100 series, USA), Rheometer (Anton, MCR300, Austria), Milk analyzer bar (Azmalaban, MCC, Iran), pH meter (Knick,766, Germany), Digital scale 0.001 (AND,GF4000, Japan), Psychrometer (Sartorius, MA45, Germany), Oven (memmert, UM400, Germany), Centrifuge (Funke Gerber, Nova safety, Germany), Kjeldahl (Gerhardt, KB, Germany), Refrigerated incubator (WTW,TS606-6/2-i, Austria), Incubator (memmert, BM400, Germany),  Autoclave (RT-2, Reyhan Teb, Iran). In the present study the effect of a decrease in lactose percentage on the durability, flavor and sensory (organoleptic) properties of produced doogh on the 1st, 23rd and 46th day’s after production time in comparison to control ones, was  investigated. The changes of acetaldehyde levels were measured using Gas chromatography mass spectroscopy. In this study, milk was passed through UF filters in three consecutive days and its lactose level was decreased by about 2%. After that fermentation and standardization of doogh based on the amount of fat and solid-nonfat has been done. All tests were repeated 3 times and the comparison of averages has been done by using LSD test (p= 0.05 %). Results were expressed as mean ± SE. Values were the average of triplicate experiments. Significant differences between the results were calculated by analysis of variance (ANOVA) with the help of SPSS software version 20. Differences at P<0.05 were considered to be significant. Also the obtained data for the rheological experiments was processed using software such as Excel 2010 and SPSS software version 20 to determine an appropriate mathematical model. And in this case, the linear and nonlinear regressions were used.
 
Results & discussion: Results showed that by increasing the storage time, the acidity and pH changes and the acetaldehyde amount of produced doogh was less than those of the control samples. Additionally flavor and sensory properties improved considerably. Based on the findings of this research, it seems that the reduction of lactose and the decrease of lactic acid bacterial activity can play an important role in increasing the durability time, improving the sensory properties and enhancing the quality of doogh. It was determined that the decrease of lactose using ultrafiltration to the control sample not only indicates the significant changes in most considered variables but also there are these kinds of changes during the durability time. In addition, the significant and slow changes of pH to the control sample due to the decrease of lactic bacteria activities show the least qualitative and flavor changes over the durability time. And also it was specified that by increasing the activities of lactic bacteria, the amount of acetaldehyde will increase but by decreasing this activity, the level of acetaldehyde will decline. This issue has a direct relationship with the changes of lactose's amount. The post-filtration doogh due to its high amount of proteins shows high viscosity and concentration and for this reason, the attention of panelists in the sensory evaluation was directed toward choosing the post-filtration doogh instead of the pre-filtration one. Therefore, it can be concluded that the decrease of lactose using ultrafiltration has a main role in improving the quality of the product and also the tendency of the consumers. 

Keywords

علیزاده, آیناز, احسانی, محمدرضا و صفری, محمد. (1388). تاثیر پروتئین های شیر تغلیظ شده به روش اولترافیلتراسیون بر خواص شیمیایی و حسی ماست. فصلنامه علوم و صنایع غذایی, 6(3), 115-109.
مظاهری اسدی مهناز و پوراحمد, رضوان. (2012). بررسی میزان استالدهید در ماست های تولید شده بوسیله سویه‌های میکروبی بومی. علوم غذایی و تغذیه, 7(2), 76-83.
Ahmadi, E, Mortazavian, AM, & Mohammadi, R. (2013). The Effect of Heat Inactivating Process on Biochemical, Microbiological and Sensory Characteristics of Iranian Drink Based on Fermented Milk (Doogh). J Food Process Technol, 4(271), 2.
Alvarez, F, Argüello, M, Cabero, M, Riera, FA, Alvarez, R, Iglesias, JR, & Granda, J. (1998). Fermentation of concentrated skim‐milk. Effects of different protein/lactose ratios obtained by ultrafiltration–diafiltration. Journal of the Science of Food and Agriculture, 76(1), 10-16.
Azarikia, F, Abbasi, S, & Azizi, MH. (2009). Investigation of the efficiency and mechanisms of some hydrocolloids on the stabilization of Doogh. Iranian Journal of Nutrition Science and Food Technology, 4(1), 11-22.
Azarikia, Fatemeh, & Abbasi, Soleiman. (2010). On the stabilization mechanism of Doogh (Iranian yoghurt drink) by gum tragacanth. Food Hydrocolloids, 24(4), 358-363.
Bagheripoor Fallah, N., Mortazavian Farsani, S. A. M., Hosseini, H., Shahraz, F., & Bahadori Monfared, A. (2016). Identification of microorganisms in industrial Iranian Doogh. journal of food science and technology, 13(57), 185-202.
Biliaderis, CG, Khan, MM, & Blank, G. (1992). Rheological and sensory properties of yogurt from skim milk and ultrafiltered retentates. International Dairy Journal, 2(5), 311-323.
Brazuelo, Agustin, Suarez, Elena, Riera, Francisco A, Alvarez, Ricardo, Igesias, Jose R, & Granda, Juan. (1995). Protein‐enriched yoghurt by ultrafiltration of skim‐milk. Journal of the Science of Food and Agriculture, 69(3), 283-290.
CodexAlimentarius, Commission. (2011). Joint FAO/WHO food standard programme, project document for a regional standard for Doogh: Tunisia.
Ehtiati, ahmad, Shahidi, fakhri, Mohebi, mohebbat, & Yavarmanesh, masoud. (2013). Evaluation of WPC and EPS Producing Starter Cultures Effect on some Physical Properties of Doogh. Iranian Food Science and Technology Research Journal, 9(4), 295-303.
Fallah, Aziz A., Rahnama, Mohammad, Jafari, Tina, & Saei-Dehkordi, S. Siavash. (2011). Seasonal variation of aflatoxin M1 contamination in industrial and traditional Iranian dairy products. Food Control, 22(10), 1653-1656.
Foroughinaia, S., Abbasi, S., & Hamidi Esfahani, Z. (2007). Effect of Individual and Combined Addition of Salep, Tragacantin and Guar Gums on the Stabilisation of Iranian Doogh. nsft.ir, 2(2), 15-25 (in persian).
Gharibzahedi, Seyed Mohammad Taghi, & Chronakis, Ioannis S. (2018). Crosslinking of milk proteins by microbial transglutaminase: Utilization in functional yogurt products. Food Chemistry, 245, 620-632.
Hugenholtz, J. (2013). Traditional biotechnology for new foods and beverages. Current opinion in biotechnology, 24(2), 155-159.
ISIRI. (2008). (Institute of Standards and Industrial Research of IRAN). No. 2543 Doogh-Specifications and test method. Karaj: 2nd rd.
Jahadi, Mahshid, Ehsani, MohammadReza, NavabPoor, Sorayya, HashemiRavan, Mahnaz, SarallahZabihi, Sajjad, & Joodaki, Amin. (2007). Evaluation of milk constitute retentate with ultrafiltration. Journal of Iran agriculture sciences, 38(2), (in Persian).
Loones, A. (1989). Transformation of milk components during yogurt fermentation. Yogurt: nutritional and health properties. McLean, VA: National Yogurt Association, 95-114.
McSweeney, Paul LH. (2009). Lactose, water, salts and minor constituents: Springer.
Meshkani, S.M, & Mortazavi, S.A. (2017). Optimization of Formulation of Fermented Dairy Beverage (Doogh) Containing Whey Powder and Commercial Stabilizer Using Response Surface Design. journal of food science and technology, 14(66), 47-39.
Mistry, VV, & Hassan, HN. (1992). Manufacture of nonfat yogurt from a high milk protein powder. Journal of Dairy Science, 75(4), 947-957.
Özer, Barbaros H, & Kirmaci, Huseyin Avni. (2010). Functional milks and dairy beverages. International Journal of Dairy Technology, 63(1), 1-15.
Renner, Edmund, & Abd-El-Salam, MH. (1991). Application of ultrafiltration in the dairy industry: Elsevier Science Publishers Ltd.
Tamime, Adman Y, & Robinson, Richard Kenneth. (1999). Yoghurt: science and technology: Woodhead Publishing.
Uebelacker, Michael, & Lachenmeier, Dirk W. (2011). Quantitative determination of acetaldehyde in foods using automated digestion with simulated gastric fluid followed by headspace gas chromatography. Journal of Analytical Methods in Chemistry.
Wouters, Jan TM, & Geurts, TJ. (2006). Dairy Science and Technology. Food Science and Technology: CRC Press.
Yerlikaya, Oktay. (2014). Starter cultures used in probiotic dairy product preparation and popular probiotic dairy drinks. Food Science and Technology (Campinas), 34(2), 221-229.
Zamani Mazdeh, F, Esmaeili Aftabdari, F, Moradi-Khatoonabadi, Z, Shaneshin, M, Torabi, P, Shams Ardekani, MR, & Hajimahmoodi, M. (2014). Sodium benzoate and potassium sorbate preservatives in Iranian doogh. Food Additives & Contaminants: Part B, 7(2), 115-119
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