EFFECT OF NATURAL ACIDIFYING AGENST AND STORAGE TEMPERATURE ON QUALITY OF UNRIPEND WHEY CHEESE

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1 EFFECT OF NATURAL ACIDIFYING AGENST AND STORAGE TEMPERATURE ON QUALITY OF UNRIPEND WHEY CHEESE By K.A. Abdel-Razig and A.S. AlGamry Department of Food science and Technology, Faculty of Agriculture Al-Zaiem Al-Azhari Univercity. P.O. Box Khartoum North 13311Sudan. ABSTRACT The effect of acidifying agents and storage temperature on the quality of unripend whey cheese was investigated. The acidifying agents namely, white vinegar, lemon juice and grapefruit juice were added during heat treatment of the whey at 90 C where the curd moved and accumulated at the surface, extracted and squeezed for overnight. The curd was cut into pieces, 10% of salt was added and packed into plastic bags (polyethylene). The cheese was stored for two months at cold temperature (4 ± 2 C) and room temperature (30 ± 11 C). Analysis was carried out at intervals of 0, 15, 30, 45 and 60 days during storage. The total solids increased significantly (P 0.05) due to the loss of moisture content. The increase was more (33.09%) when white vinegar was used compared to (32.65%) and (31.95%) for lemon and grapefruit cheese respectively. The titratable acidity increased significantly (P 0.05) during storage due to high fermentation potential of the whey lactose to produce lactic acid. Significant increase (P 0.05) was recorded in the levels of proteins during storage. The increase was more with cheese processed by white vinegar (18.00%), compared to cheese processed by lemon (16.96%) and grapefruit cheese (17.09%). The fat content increased in all cheese samples during storage period. The ash content of the cheese gradually increased during storage time. The increase was more with lemon cheese (4.49%), compared when it was processed by grapefruit juice (3.43%) and white vinegar (2.95%). The samples stored at room temperature got a good score at 15 days of storage and had a shelf life of 30 days, while that stored at cold temperature had a good score at 30 days of storage and still better till the end of storage 119

2 period (60 days). Samples stored at cold temperature were significantly the best (P 0.05) than samples stored at room temperature. White vinegar cheese was significantly the best (P 0.05), than lemon cheese, and grapefruit cheese. الملخص : تمت دراسة تاثير المواد الحمضية ودرجة حرارة التخزين على نوعية جبن الشرش. صنعت الجبن باستخدام الشرش مع اضافة ا حماض كمواد مخثرة (الخل الطبيعي عصير الليمون وعصير القريب فروت) ا ثناء المعاملة الحرارية لدرجة 90ºC حيث تكونت الخثرة على سطح الشرش. استخلصت الخثرة ثم ضغطت طوال الليل. قطعت الخثرة ثم اضيف الملح بنسبة %10 وتمت تعبي تها في ا كياس بلاستيكية (بولي ايثيلين). خزنت عينات الجبن لمدة شهرين على درجة حرارة الغرفة (30±11 C) ودرجة حرارة الثلاجة( 4±2ºC ). ا ختبرت العينات خلال فترة التخزين و 60 يوما. تزايد محتوي البروتين معنويا (0.05 P) خلال فترة التخزين. وكان التزايد اكثر في عينات الجبن المصنعة بالخل الطبيعي (%18.00) مقارنة بعينات عصير الليمون (%16.96) وعصير القريب فروت (%17.09). كان محتوى الرماد ا كثر في العينات المصنعة بواسطة عصير الليمون (4.49%) مقارنة بالعينات المصنعة بواسطة عصير القريب فروت كل العينات خلال فترة التخزين. (3.43%) والخل الطبيعي (2.95%). كما تزايد الدهن في تناقصت قيمة الpH لتخمر سكر اللاكتوز وانتاج حامض اللاكتيك. بينما ازدادت الحموضة المعايرة نتيجة ا ظهر التقييم الحسي لجبنة الشرش ا ن العينات المصنعة بواسطة الخل الطبيعي والمخزنة في الثلاجة هي الافضل مقارنة بالعينات الاخرى. تدهورت صفاتها بعد فترة تخزين 30 يوم الثلاجة كانت ذات صفات جيدة حتى نهاية فترة التخزين. العينات المخزنة عند درجة حرارة الغرفة في حين ا ن العينات التي خزنت عند درجة حرارة INTRODUCTION 120

3 Ricotta cheese is traditionally made from whey (the watery stuff from milk that's left over when making other kinds of cheese) or from a combination of whey and whole or skim milk. In fact, "Ricotta" means" recooked," referring to the notion that it's made by heating the whey that came from another cooked cheese (Kilic and Lind, 2004). During production, the sweet whey is heated to a temperature of 200 degrees Fahrenheit. Citric acid may be used to help separate the protein from the water in the whey. Usually, Ricotta cheese-makers will use the whey left over from making mozzarella or provolone, but whey from Romano cheese-making is used for a special type of Ricotta, "Ricotta romana." The whey usually comes from cow's milk, but some types of Ricotta are made with ewe's milk whey. A traditional Ricotta is made from sheep's milk whey, most often remaining after making Pecorino Romano. Ricotta is a soft cheese that has a fine, moist, grainy texture. Ricotta sometimes is not classified as cheeses, because they are obtained from whey and cream respectively, both are coagulated without rennet but by the combined effects of high temperature and acidity. They are fresh, unsalted dairy product. Ricotta made from sheep's milk whey can be salted and ripened (Ricotta salata, i.e salted Ricotta). No attempt has been done in the Sudan to produce this type of cheese. The objectives of this work are, to produce a domestic new kind of cheese (Ricotta) that will add to the dietary status of milk products that would eventually increase income revenues in rural areas, and to study the effect of natural acidifying agents and storage temperature on quality of unripend whey cheese. MATERIALS AND METHODS Materials A seweet whey of Sudanese white soft cheese processing was obtained from Raira factory at Hellat Kuku. White vinegar, lemon, grape fruit and salt from local market of Khartoum North. Methods 121

4 Preparation and storage of cheese This study used three batches of equal quantity of 400 liters of sweet whey obtained after processing white cheese. The whey samples were kept in three separate tanks. Amounts of acidifying agents were calculated based on 0.05% of the 400 liters of the whey sample. The acidifying agents used were namely white vinegar (N 0.01, ph 2.1), lemon juice (N 0.2, ph 3.2) and grapefruit juice (N 0.1, ph 3.2). It is to be noted that the purpose of adding the acidifying agents is to lower the ph values in order to assist the precipitation of the whey proteins (Lactalbiumin and Lactoglobulin). Each of the calculated amounts of the acidifying agents were added to the respective whey samples in three portions. After addition, the samples were heated up to 20 C, 40 C and 80 C and stirred every 5 minutes till 15 minutes. Upon heating to 90 C by live steam, the proteins began to precipitate in the form of surface foam that was skim off every time. The retained curd in the whey rose to the surface and left for 5-8 minutes to cool down. Then, the curd was moved to the centre of the tank to become more firm (Plate 1, 2, 3). The curd then was put into small perforated cylindrical metal molds lined with cheese-cloth and pressed overnight by 2.5 kg weight. After the pressing time elapsed, the curd was removed from the molds and cut into small cubes. Each of the one kg of the three cheese samples was packed in plastic bags (polyethylene), and then warm water containing 10 % salt was added. The three samples (Plate 4, 5, 6) were stored for 0, 15, 30, 45 and 60 days at cold temperature (4±2 C) and room temperature (30±11 C). Physical, chemical and statistical analysis The total solids, titratable acidity, protein content, fat content, ash content was determined according to AOAC (1990), sensory evaluation according to the method described by Ihekoryne and Ngoddy (1985) and statistical analysis was carried out using the statistical analysis system (SAS, 1997). RESULTS AND DISCUSSION Table 1. Shows changes in total solids of unripend whey cheese during storage period as affected by three kinds of acidifying agents. The total solids of cheese increased significantly (P 0.05) with storage time 122

5 progress.the increase in samples stored at room temperature (30±11 C) was significantly (P 0.05) more compared to samples stored at cold temperature (4±2 C). White vinegar cheese recorded the highest total solids (33.40%), which was significantly higher (P 0.05) than respective values of lemon (32.65%) and grape fruit cheese (31.95%). The increase in total solids of unripend whey cheese during storage period was said to be attributed to the decrease in moisture content and /or difference in acidifying agents (Nilson and Streiff, 1979; Amer et al., 1978; Kleyn and Pintario; 1980; Jelen, 1992; Modler and Emmons, 1994; Sieber, 1998 and Abdel-Razig et al., 2002). Table 2. Shows changes in titratable acidity of unripend whey cheese during storage period as affected by acidifying agents. The titratable acidity of unripend whey cheese was significantly (P 0.05) increased during the storage time progress. The increase in acidity of samples stored at room temperature was significantly (P 0.05) more compared to samples stored at cold temperature. White vinegar cheese stored at room temperature produced the highest acidity (1.80%), which was significantly (P 0.05) higher than respective values of lemon cheese (1.69%) and grapefruit Cheese (1.58%). It was reported earlier that about 80-90% of the increase in acidity during storage of cheese at both temperatures was mainly due to the lactic acid formed by a predominating lactic acid bacteria (True and Patel, 1973; Jelen, 1992; Abdel-Razig, 1996 and Mahran et al., 2000 and El Owni and Hamid, 2008). Table 3. Shows changes in protein contents of unripend whey cheese during storage period as affected by acidifying agents. A significant increase (P 0.05) was recorded in the level of protein of cheese as storage period progressed. The increase in protein was more with samples stored at room temperature (30±11 C) compared to samples stored at cold temperature (4±2 C). White vinegar cheese stored at room temperature produced the 123

6 J.Sc. Tech ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ Vol. 10(2) 2009 Plate 1.Curd of cheese using white vinegar as an acidifying agent. Plate 2.Curd of cheese using lemon juice as an acidifying agent. Plate 3.Curd of cheese using grape fruit juice as acidifying agent. 124 Plate 4.Ricotta cheese preparation using white vinegar as acidifying agent. Plate 5. Ricotta cheese preparation using Lemon juice as acidifying agent. Plate 6. Ricotta cheese preparation using grape fruit juice as acidifying agent.

7 highest protein content (18.00%), which is significantly higher (P 0.05) than respective values of lemon cheese (16.96%) and grapefruit cheese (17.09%).The total protein content was increased due to the loss of moisture content during storage period. (Nilson and Streiff, 1979; Shahani et al., 1978; Amer et al., 1978; Kleyn and Pintario, 1980; Jelen, 1992; Modler and Emmons 1994; Sieber, 1998 and Abdel-Razig, 2006). Table 4. Shows changes in fat contents of unripend whey cheese during storage period as affected by acidifying agents. A significant increase (P 0.05) was observed in fat content of cheese as storage period progressed. The increase in fat was more with samples stored at room temperature compared to sample stored at cold temperature (Amer et al., 1978 and El Owni and Hamid, 2008). White vinegar cheese recorded the highest fat content (9.06%), which was significantly higher (P 0.05) than respective values of grapefruit cheese (7.70%), and lemon cheese (7.29%). The fat content showed a tendency to increase due to the rapid loss in moisture of cheese (Kleyn and Pintauro, 1980; Jelen, 1992; Modler and Emmons, 1994; Abdel- Razig, 1996; Sieber, 1998 and Mahran et al., 2000). Table 5. Shows changes in ash content of unripend whey cheese during storage period as affected by three kinds of acidifying agents. The ash content of cheese increased significantly (P 0.05) as storage time progressed. The increase in samples stored at cold temperature (4±2 C) was significantly more (P 0.05) compared to samples stored at room temperature (30±11 C). Lemon cheese recorded the highest ash content (4.49%), which was significantly higher (P 0.05) than respective values of grapefruit (3.43%) and white vinegar cheese (2.95%).The increase in ash content of unripend whey cheese during storage period was attributed to the decrease in moisture content (Amer et al., 1978; Nilson and Streiff, 1978; Kleyn and Pintario, 1980; Jelen, 1992; Modler and Emmons, 1994 and Sieber, 1998) White vinegar cheese was significantly the best (P 0.05), in quality than lemon cheese, and grapefruit cheese. The samples stored at room temperature got a good score till day 15 th of storage and had a shelf life of 30 days, while that stored at cold temperature had a good score at day 30 th and 125

8 still better till the end of storage. Samples stored at cold temperature were significantly (P 0.05) the best than samples stored at room temperature (Weatherup, 1986 and Mucchetti et al., 2002). Table 1. Changes in total solids content* (%) of unripend whey cheese during storage as affected by acidifying agent. Acidifying agent Storage period (Days) White vinegar Lemon juice Grapefruit juice R** C** R** C** R** C** f f fg fg g g d de d e de ef a cd c d c bc c d a b c * Mean values having different superscript letters in columns and rows are significantly different (P 0.05). R ** Room store temperature (30±11 C); C ** cold store temperature (4±2 C). Table 2.Changes in titratable acidity* (% lactic acid) of unripend whey cheese during storage as affected by acidifying agents. Acidifying agent Storage period White vinegar Lemon juice Grapefruit juice (Days) R** C** R** C** R** C** i 1.00 i 1.01 hi 1.01 hi 1.03 hi 1.03 hi b 1.21 fg 1.50 c 1.10 h 1.32 d 1.03 hi a 1.22 f 1.69 b 1.11 h 1.58 c 1.09 hi e gh h de g h * Mean values having different superscript letters in columns and rows are significantly different (P 0.05). R ** Room store temperature (30±11 C); C ** cold store temperature (4±2 C). Table 3. Changes in protein content* (%) of unripend whey cheese during storage as affected by acidifying agent. Acidifying agent Storage period White vinegar Lemon juice Grapefruit juice (days) R** C** R** C** R** C** g g g g g 13.5 g de ef e f e fg a cd c d bc ef ab c d a ab b * Mean values having different superscript letters in columns and rows are significantly different (P 0.05). R ** Room store temperature (30±11 C); C ** cold store temperature (4±2 C). 126

9 Table 4. Changes in fat content* (%) of unripend whey cheese during storage as affected by acidifying agent. Acidifying agent Storage period White Grapefruit Lemon juice (days) vinegar juice R** C** R** C** R** C** ef 5.66 ef 5.00 f 5.00 f 4.96 g 4.96 g d 6.61 de 6.61 de 5.67 h 6.72 de 5.85 e a 7.52 de 7.29 cd 6.74 de 7.70 c 6.48 de ab cd d ab c b * Mean values having different superscript letters in columns and rows are significantly different (P 0.05). R ** Room store temperature (30±11 C); C ** cold store temperature (4±2 C). Table 5. Changes in ash content* (%) of unripend whey cheese during storage as affected by acidifying agent. Acidifying agent Storage period Grapefruit White vinegar Lemon juice (days) juice R** C** R** C** R** C** i 1.90 i 2.90 de 2.90 de 2.11 h 2.11 h ef 2.25 f 3.83 bc 3.35 ef 2.84 de 2.47 e d 2.52 e 4.18 b 3.88 bc 3.19 d 2.75 de de b d de a c * Mean values having different superscript letters in columns and rows are significantly different (P 0.05). R ** Room store temperature (30±11 C); C ** cold store temperature (4±2 C). 127

10 REFERENCES 1. Abdel-Razig, A.K. (1996). The production of white soft cheese from different milk sources.m.sc Thesis. Univercity of Khartoum Sudan. 2. Abdel-Razig, A.K.; Ahmed, R.A. and Mohamed, E.B. (2002). Ripening behavior of Sudanese bradied cheese (Mudafara). First international conference on miotechnology, application for the arid Regions. Puplished by the Kuwait institute for scientific Research 1: Abdel-Razig, A.K.; Ahmed, R.A. and Mohamed, E.B. (2006). Effect of the level of salt on the chemical quality of Sudanese bradied cheese (Mudafara) during storage. FRC\ J. Fd. Sci. and Technol. 1: Amer, S.N.; Girgis, E.S. and Ibrahim, M.K. (1978). Effect of milk heating temperature on Ricotta cheese properties. Annals of Agriculture. Sci. Moshtohor, 9: AOAC, (1990). Official method of analysis. 15 th ed. Association of official analytical Chemistry. Washington. D.C; U.S.A. 6. El Owni, A.O and Hamid, I.A. (2008). Effect of storage period on weight loss, chemical composition, microbiological and sensory characteristic of Sudanese white soft cheese (Gibna Bayda). Pakistan J. of Nutrition 7 (1): Jelen, P. (1992). Whey cheese and beverages in whey and lactose processing ed. By Zadow, J.G. Elsevier Applied Sci. Ltd. Pp Kilic, M. and Lind, R.C. (2004). Utilization of sheep s milk cheese whey in the manufacture of on alkyl phenol flavours concentrate. J. Diary Sci, 87, Kleyn, D.H. and Pintario, N.D. (1980). Quality atitude of mozzarella and Ricotta cheese in New Jersey. J. Diary Sci. 63: Mahran, E.S; Shehata, A.E and El.Samragy, Y.A. (2000).Ricotta cheese quality and organoleptic during storage period.j. Dairy Sci.71(11): Modler, H.W. and Emmons, D.B. (1994). Yield of cheese base material produced by a pplication of continuous Ricotta processing 128

11 technology. Cheese yield and factors affecting its control. J. Diary Sci Mucchetti, G.; Carminati, D. and Pirisi, A. (2002). Fresh Ricotta cheese from cow s and ewe milk. Observations on production techniques and the product. Latte, 27: 2, Nilson, K.M. and Streff, P. (1979). Whey: composition of whey Ricotta cheese manufactured from whey and whey concentrates. American Diary review, 40 (10): SAS, (1997). Statistical analysis system. SAS User s: Statistics SAS Institute Inc. Editors, Cary. NC. 15. Shahani, K.M.; Mathur, B.N. and Kilare, A. (1978). Utilization of whey as a human food cultured. J. of Diary Prod. 13 (2): Sieber, L.S. (1998). Predicting formulas for the yield of cheese from composition of milk: A review J. of Diary Sci., 73, True, L.C. and Patel, G.R. (1973). Recoverd Ricotta cheese whey acceptable as snack dipase. Indian J. Diary Sci.7(4): Weatherup, W. (1986). The effect of processing variables on the yield and quality of Ricotta cheese. J. of Diary industries, 51 (9):

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