Effect of Polyols on The Rheological and Sensory Parameters of Frozen Dough Pizza

Food Sci. Technol. Res., 18 (6), 781 787, 2012 Effect of Polyols on The Rheological and Sensory Parameters of Frozen Dough Pizza Ali Asghar 1*, Faqir Muhammad Anjum 1, Masood Sadiq Butt 1, Muhammad Atif Randhawa 1 and Saeed Akhtar 2 1 National Institute of Food Science and Technology, University of Agriculture, Faisalabad, Pakistan. 38040 2 Department of Food Science and Technology, University College of Agriculture, Bahauddin Zakariya University, Multan, Pakistan Received June 5, 2008; Accepted August 24, 2012 Polyols are also important functional ingredients usually behave as humectants in different food products. Frozen dough bakery products face a challenge of relatively short shelf life with decreasing quality characteristics with the increasing frozen storage periods of time. The objective of this study was to determine the effect of different levels of Polyols on the rheological and sensory parameters of frozen dough Pizza during different storage interval of time. Different Polyols levels (sorbitol and mannitol) were studied on flour basis on the rheological properties of commercial wheat flour and their effect on the organoleptic paramters in frozen dough pizza (FDP) were monitored after 0, 15, 30, 45 and 60 days of frozen storage. It was observed that water absorption, arrival time, departure time, peak time and tolerance index was higher in flours containing 2% addition of polyols (sorbitol and mannitol) treatments in the commercial wheat flours for the empirical rheological measurements. Addition of sorbitol and mannitol at the level of 2% on flour weight basis improved the quality of frozen dough pizza while sensory parameters of frozen dough pizza effected significantly during the storage periods. Keywords: frozen dough pizza, polyols, empirical rheology, frozen storage *To whom correspondence should be addressed. E-mail: ali_ft@hotmail.com Introduction Baking industry is getting diversification with time in use of different type of dough additives. Choice for the use of different additives is available depending upon their functional properties. Currently different additives are being used in the bakery products to improve quality and shelf life. Polyols are important functional ingredients usually behave as humectants in different food products. It is of particular interest to study water-binding properties of polyols (mannitol and sorbitol) as humectants when protein and starch release the water in frozen dough systems. These polyols could potentially improve the quality of the frozen dough bakery products by reducing the water mobility during frozen storage. Polyols or sugar alcohols are among common osmoprotectant compounds, which form strong association with water molecules via hydrogen bonds. Sorbitol and mannitol are sugar alcohols and are used in the foods for their humectants properties. Polyols or polyhydric alcohols are straight chain organic compounds in which the only functional group present is hydroxyl. Polyols are used mainly in the food industry as hygroscopic agent or humectants, crystallization modifier, softening and plasticizing agent (Griffin and Lynch, 1968). For ages, it has been believed that there is no substitute for fresh baked goods. With lapse of time, a crispy crust of a fresh baked product develops a moist and leathery texture while the soft crumb becomes firm and dry. The fresh flavor is also lost within hours of baking, which has made bakers work midnight or early morning to provide the consumers with fresh bread on a daily basis. Transportation of baked products from large automated bakeries has also posed problems (Inoue and Bushuk, 1991) The use of frozen dough saves time, space, and equipment costs for the small retail or in-store baker who freshly bakes a wide variety of bread on the premises. Despite additional costs for freezing, transportation, and frozen storage, the use of frozen dough can be attractive, especially when producing freshly baked products of high added value at relatively expensive locations. Pizza Restaurants have also been established in the main cities of the country and since the shelf life of frozen dough is less and the products from the frozen dough also loses its acceptability after 72 hours. This situation demands that ways and means should be explored

782 Material and Methods Procurement of raw material The commercial wheat flour used in this study for making of FDP has generously been provided by Pizza Hut Pakistan and other ingredients i.e. sugar, salt, shortening, yeast were purchased from local market. Polyols i.e Sorbitol and Mannitol used in this study were food grade manufactured by Sigma Corporation were purchased from Standard Scientific Store Faisalabad, Pakistan. Chemical analysis of flour Commercial wheat flour was analyzed for moisture, crude protein, crude fiber, crude fat, nitrogen free extracts, total ash as well as wet and dry gluten content according to AACC method (AACC, 2000). Empirical rheological studies of wheat flour Mixographic characteristics Empirical rheological properties of commercial wheat flours were determined with and without the addition of polyols. Mixograph equipped with 10 g bowl capacity (National Mfg. Co. Lincoln Nebraska) was used to prepare the Mixograms from the commercial wheat flour with the different levels of additions of polyols. The values of mixing time and peak height were recorded according to method as described in (AACC, 2000) Farinographic studies The physical dough characteristics of the commercial wheat flour were studied to check the behavior of the wheat flour with the different treatments of polyols. Parameters recorded during these analyses by using Brabender Farinograph according to method of (AACC, 2000) were water absorption capacity, dough development time, dough stability, softening of the dough, resistance of the dough and arrival time. Preparation of frozen pizza dough Pizza shell from froto improve the shelf life and stability of the frozen dough end product. Loss of stability refers to increase in proof time, decrease in loaf volume with poor bread characteristics, and loss of shelf life (Wolt and D Appolinia, 1984). The quality of frozen dough decreases with increasing frozen storage time (Asghar et al., 2009, 2011; Inoue and Bushuk, 1996; Nemeth et al., 1996). Pizza is consumed worldwide and is the food of choice of a large number of urbane population. It is a type of flat bread chemically or yeast leavened containing different types of topping, especially comprising of cheese, chicken and tomato sauce with some other variables depending on the choice of consumer. The pizza dough base or shell comprises about 40% of the weight and remaining 60% consists of topping (Spooner, 1993; Lorenz and Kulp, 1995) Hase et al. (1981) studied the effect of sugar alcohols (polyols) on the gelatinization and retrogradation of potato and corn starch and found that the presence of sugar alcohols (polyols) reduced the retrogradation of gelatinized starch. It was also found that the water holding capacity of gelatinized starch was better maintained when sugar alcohol was added after gelatinization than when added from the beginning of gelatinization. Rayas et al. (2000) reported that mannitol is one of the osmoprotectant compounds for their drought protection properties in wheat. It has been shown that some polyols have very efficient osmoprotectant properties. Frozen dough products face a challenge of relatively short shelf life with decreasing quality characteristics appearing at about four weeks of frozen storage. Selected mannitol levels were studied and their effect on the rheological properties and shelflife quality of frozen dough monitored. Different mannitol levels were used on flour basis in a bread stick formula and bread stored at ( 10 ) for six weeks. Bread volume, texture, crust & crumb characteristics were observed and low concentrations (0.01 and 0.1%) showed the most beneficial effect. Suhendro et al. (1995) studied the effect of polyols (glycerol, sorbitol, propylene glycol and maltitol) on the processing and qualities of wheat tortillas (tortilla is a round, thin, unleavened wheat or corn bread) prepared from wheat flour of different protein content and reported that low protein flour required less water and shorter mixing time as compared to high protein flour, similarly addition of 2% or 4% polyols did not effect the mixing time of tortilla doughs but addition of 6% polyols cause the decrease in mixing time. The tortilla doughs with 6% polyols were also stickier as compared to 2% or 4% polyols doughs. The tortillas prepared from 6% polyols were darker and had more brown A. Asghar et al. spots. It was also observed that some polyols increase the shelf stability of tortillas when prepared from flour of higher protein contents (11 11.5%). It was found that tortillas containing polyols had less moisture, higher liquid content and improved shelf life stability except when prepared from low protein (10.2%) wheat flour. It was also found that water activity decreased with increasing polyol level. Baking industry uses crystalline sorbitol and sorbitol solution in products for special dietary use, and as humectants to extend the shelf life of baked goods (Friedman 1978). Properties of sorbitol, which make it useful food additive and it is chiefly used as humectants in bakery products (Heaton et al., 1980). Objective of this research work were to study the effect of poylols (sorbitol and mannitol) on the empirical rheological properties of pizza dough flour and also its effect on the quality shelf life and sensory attributes of frozen dough pizza during prolong storage periods of time.

Effect of Polyols on The Rheological and Sensory Parameters of Frozen Dough Pizza 783 zen dough, prepared according to the procedure described by (Asghar, 2007) Following recipe was used for frozen dough pizza shell preparation. Flour = 100 g Sugar = 3 g Salt = 2 g Yeast = 3 g Shortening = 1 g Polyols = as per treatment shown in Table 1 Water = According to water absorption determined through farinograpgh Pizza Shell Preparation Doughs for the making of pizzas were made in the bakery pilot plant of the Food Science department of University of Agriculture, Faisalabad, Pakistan. Measured amount of water was added into the mixing bowl. After this sugar, salt and yeast were taken in the mixing bowl and stirred with a hand stirrer for 1 min. Then oil was added, followed by addition of flour. The mixing was carried out at slow speed for 10 min. After mixing, the dough was taken out and placed on cutting board. The pizza dough were divided into pieces, rounded, and rested in a fermentation cabinet for 10 min at 30 and 70 75 relative humidity. Then the dough was molded manually and immediately wrapped in polyethylene zip bags and frozen in freezer at 18. After every 15 days, thawing of the dough was carried out by keeping the dough at room temperature for 45 min. Then mixing of thawed dough was done for 1 1.5 min in order to homogenize then dough were first rounded by hand and then flatten by roller and placed in pans, pretreated with 16 g oil. Pans containing pizza base were allowed to proof for 45 min at 35 temperature and 85% relative humidity. Application of topping and baking of pizza After proper proofing of pizza shells, topping was done. A variety of topping could be made on pizzas but in this experiment, boiled chicken, cheese, tomato paste, onion, pepper, and tomato were applied on shell as topping. Tomato paste used in this study was manufactured in the National Institute of Food Science and Technology, University of Agriculture, Faisalabad, Pakistan and 70 g of tomato paste were spread on pizza shell leaving the edges of pizzas. Processed cheddar cheese manufactured by Deen s dairies Pvt. Ltd Sahiwal Pakistan was purchased from local market. 120 g of cheese was used for each pizza in two stages and two toppings were applied. First topping was made just after tomato paste application. While second toping was made at the top after the application of vegetables and chicken meat. The meat was separated from bones and 50 g of this was applied on each pizza. Chopped onion, green chilies and sliced tomatoes were applied at 30 g, 30 g and 15 g weight, respectively The prepared pizzas were baked in rotary oven at 240 for 12 to 14 min. Sensory analysis of frozen dough pizza Sensory analysis of pizzas made from frozen dough at different interval of time by done by employing a panel of experienced judges for color of crust, crumb, aroma, flavor, texture, crunch, after taste and over all acceptability by using hedonic scale according to the method as described by Land and Shepherd (1988). Statistical analysis Statistical differences among data obtained from polyols treatments and their effect on sensory evaluation of frozen dough pizza were carried out using the analysis of variance (ANOVA). The level of significance between quality parameters of different polyols treatments by using completely randomized design and their means were compared according to the appropriate methods as described by (Steel et al., 1997) Treatments Table 1. Experimental design. Sorbitol Polyols Mannitol T c T s1 0.1% T s2 0.5% T s3 1.0% T s4 1.5% T s5 2.0% T m1 0.1% T m2 0.5% T m3 1.0% T m4 1.5% T m5 2.0% T c = Acts as control without any polyol treatment. Results and Discussion Chemical analysis of flour The commercial wheat flour used in this study for the making of pizza were chemically analyzed and the values for the moisture, ash, crude protein, crude fat, crude fiber of the flour were 12.2, 0.5, 13.2, 1.4 and 0.3% respectively. While the values of wet and dry gluten of flour determined in this study were 32.12 and 10.64% respectively. The results found in this study match with the findings of (Marston, 1978 and Stauffer, 1993) according to them flour, with a protein content of 11 14%, are recommended for the use in frozen dough products. Empirical rheological properties Empirical rheological properties of commercial wheat flour were determined with and without the addition of polyols treatments to study their physico-rheological properties and their suitability for the

784 These results found in this study were in close agreement to the findings of Suhendro et al. (1995) who studied the wheat tortillas and reported that there is decrease in mixing time with the increase in the polyols levels in the tortillas dough. Similarly Farooq (1996) reported that with the addition of different polyol levels in the flour resulted in the decrease of mixing time of the bread and chapatti doughs which are also in consonance to the current findings. Farinographic studies The results pertaining to farinographic parameters of commercial wheat flours containing different level of polyols (Sorbitol and Mannitol) have been presented in Table 4. It is obvious from the results that value of water absorption capacity increased with the increasing levels of polyols treatments in the commercial wheat flours. Its value is maximum in T m5 (66.2%) containing 2% Mannitol followed by T s5 (65.4%) containing 2% Sorbitol whereas lowest values were recorded in control i.e. T c (61.2%) where no addition of polyols was made. As Sorbitols and Mannitols are good humectants and water binding agents used in different food products so when these were added in the commercial wheat flour, they also result in an increase in the water absorption capacity. Similarly increasing trend in the values of arrival time, departure time dough stability and other farinographic parameters has been observed with the increasing levels of polyols treatments as shown in Table 4, while a decreasing trend in the values of Tolerance Index of doughs was observed with the addition of polyols. Suhendro et al. (1995) and Farooq et al. (1996) studied the empirical rheological measurements of tortilla and wheat flour doughs with the addition of polyol treatments and found that increase in the values of water absorption capacity, dough stability were observed. So the results for the empirical rheological measurements found in this study are in close agreements to their findings. Sensory evaluation of FDP The results for the mean sum of squares of different sensory parameters of FDP are presented in Table 5. The results revealed that color, aroma, flavor, texture, crunch, taste and overall acceptability were effected significantly with the addition of different polyol treatments while the results for the crumb of the pizza were found to be non significant with the addition of different polyol levels as presented in Table 5. The statistical mean values of sensory attributes of FDP with different polyol (Sorbitol and Mannitol) are presented in Table 6. For the simplicity of data, these results are the means of triplicates and storage intervals. Results also represent that frozen dough pizzas prepared from 2% sorbitol and mannitol got significantly higher scores as compared to the rest of the treatments for the crust color, flavor and after taste, whereas frozen dough pizzas containing no added sorformation of pizza doughs by the use of Mixograph and Farinograph instruments and their results have been discussed below separately. Mixographic studies The mixograph os considered one of the classical instruments used by cereal chemists to evaluate the rheological properties of flour-water doughs. The results for statistical values for the mixographic parameters of commerical wheat flour containing different treatments of pollyols (sorbitol and mannitol) have been presented in Table 2 and 3. The results revealed that mixing time of the flour containing different levels of polyols (sorbitol and mannitol) differed significantly among different treatments while a non significant effect on the peak height percentage was observed with the addition of different levels of polyols in the commercial wheat flour samples. However, addition of sorbitol and mannitol in the wheat flour samples result in a gradual slight decrease in the mixing time while peak height percentage was not changed to a considerable extent. The mixing time values of the commercial wheat flour containing polyol (sorbitol and mannitol) were ranged from 3.40 to 3.80 min as presented in Table 3. The maximum value of mixing time was recorded in T c (3.80 min) followed by T m1 (3.65 min) while the lowest values of mixing time were recorded in T s5 (3.45 min) as shown in Table 3. Table 2. Mean squares for mixographic characteristics. SOV Df Mixing time Peak height Treatment 10 0.05 ** 8.91 NS Error 20 0.01 0.40 **, Highly significant (P > 0.01). Table 3. Mixographic characteristics of wheat flour containing polyols. Treatment Mixing Time (min.) Peak Height (%) T c 3.80 ± 0.1 52 ± 0.6 T s1 3.60 ± 0.1 50 ± 0.7 T s2 3.55 ± 0.2 49 ± 0.6 T s3 3.60 ± 0.1 51 ± 0.3 T s4 3.50 ± 0.1 48 ± 0.6 T s5 3.45 ± 0.1 48 ± 0.8 T m1 3.65 ± 0.1 50 ± 0.1 T m2 3.60 ± 0.1 48 ± 0.5 T m3 3.50 ± 0.1 49 ± 0.4 T m4 3.50 ± 0.1 48 ± 0.5 T m5 3.40 ± 0.1 47 ± 0.6 Values with the same letter in a column are not significantly different at a P > 0.05 level. T C (Control),T s1 ( 0.1% Sorbitol), T s2 (0.5% Sorbitol), T s3 (1% Sorbitol),T s4 (1.5% Sorbitol),Ts 5 (2 % Sorbitol, T m1 (0.1 % Mannitol ), T m2 ( 0.5% Mannitol ), T m3 (1% Mannitol), T m4 (1.5% Mannitol), T m5 ( 2% Mannitol). A. Asghar et al.

Effect of Polyols on The Rheological and Sensory Parameters of Frozen Dough Pizza 785 Table 4. Farinographic characteristics of wheat flour containing poylols. Treatment Water absorption Capacity (%) Arrival Time (mins) Departure Time (min) Dough Stability (mins) Dough Development Time (mins) Softening of dough (BU) Tolerance index (BU) T c 61.2 2.0 15.0 14.0 7.0 60 40 T s1 62.3 2.5 15.5 14.5 7.5 70 30 T s2 63.1 2.5 16.0 15.5 8.5 70 30 T s3 63.9 3.0 18.0 16.0 8.5 80 20 T s4 64.6 3.0 20.0 17.0 9.0 90 20 T s5 65.4 3.5 20.0 18.0 10.0 90 10 T m1 62.1 2.5 16.0 15.5 9.0 70 30 T m2 63.7 2.5 18.0 17.0 9.0 80 30 T m3 64.1 2.5 18.0 17.5 10.0 80 30 T m4 65.4 3.0 20.0 18.0 10.0 90 20 T m5 66.2 3.5 20.0 18.5 10.5 90 20 T C (Control), T s1 ( 0.1% Sorbitol), T s2 (0.5% Sorbitol), T s3 (1% Sorbitol), T s4 (1.5% Sorbitol), T s5 (2 % Sorbitol,T m1 (0.1 % Mannitol ), T m2 ( 0.5% Mannitol ), T m3 (1% Mannitol), T m4 (1.5% Mannitol), T m5 (2% Mannitol) Values are means of triplicates of all treatments. Table 5. Mean squares of the sensory parameters of frozen dough pizza. SOV Df Color Crumb Aroma Flavor Texture Crunch Taste Overall acceptability Treatment 10 1.94 ** 0.34 NS 2.87 ** 2.83 ** 1.83 ** 3.44 ** 2.46 ** 3.18 ** Storage 4 58.97 ** 36.60 ** 31.71 ** 61.77 ** 46.12 ** 34.81 ** 53.61 ** 53.87 ** Treatment Storage 40 0.07 NS 0.08 NS 0.19 NS 0.10 NS 0.15 NS 0.17 NS 0.12 NS 0.16 NS Error 220 0.19 0.18 0.18 0.19 0.19 0.18 0.19 0.18 **, Highly significant (P > 0.01), NS = Non significant Table 6. Effect of polyols treatments on sensory characteristics of frozen dough pizza. Treatments Crust color Crumb Aroma Flavor Texture Crunch After taste Overall acceptability T c 6.1 b 6.8 a 6.3 c 6.1 c 6.2 b 6.1 c 6.1 b 6.0 c T s5 7.2 a 6.9 a 6.8 bc 7.4 a 6.8 ab 6.8 b 7.5 a 6.7 b T m5 7.0 a 7.0 a 6.8 bc 7.2 ab 6.8 ab 6.8 b 7.2 a 6.8 ab T c (Control), T s5 (2 % Sorbitol), T m5 ( 2% Mannitol). Means in a column sharing same letters are statistically non- significant at 5% level of significance Duncan s Multiple Range Test and results shown in this table are the mean values of different storage periods. bitol and mannitol i.e. control (T c ) treatment got significantly the lowest statistical mean scores for these parameters. The significantly lowest scores were given to the overall acceptability of pizza prepared from control treatment (T c ). The results for the overall acceptability of the FDP were found to be better for mannitol as compared to the sorbitol and it was also observed that the addition of mannitol and sorbitol at the rate of 0.5% (T m2 ) and 1% (T s2 ) respectively on flour basis improve the overall acceptability of the FDP. Similarly (T c ) got significantly lowest scores for after taste of frozen dough pizza as shown in Table 6. The after taste was better of the pizzas prepared from sorbitol as compared to the mannitol. It was also observed that the addition of mannitol and sorbitol 2% each (T s5 ) and (T m5 ) showed more improvement in the after taste of frozen dough pizzas as shown in Table 6. The polyols have been found to have good water retention capacities and also behave as humectants which have also gel forming behavior on heating in the dough system and during the baking of pizza dough. These gelling behavior result in the strengthening of the gluten network and thus also help to improve the texture and crunch of the pizza produced from frozen doughs. The results found in this study were in close agreements to the findings of Larsen et al.

786 A. Asghar et al. Fig. 1. Effect of storage on quality of frozen dough pizza. Means in a column sharing same letters are statistically non- significant at 5% level of significance Duncan s Multiple Range Test and results shown in this table are the mean values of fresh zero day and 60 days storage periods. (1993), who studied the effect of frozen storage on the sensory evaluation of frozen dough pizza and reported the same findings. Similarly, Rayas et al. (2000) reported that mannitol is one of the osmoprotectant compounds for their drought protection properties in wheat. It has been shown that some polyols have very efficient osmoprotectant properties. Moisture redistribution in frozen dough products is due to water migration and water mobility during the frozen storage. They also found that addition of 0.01 to 0.1% level of mannitol result in an increase in the volume, crust and crumb characteristics of the baking products. Effect of storage on FDP quality The statistical result pertaining to the analysis of variance and mean sum of squares of the frozen dough pizzas during storage are presented in Table 5 and results revealed that Color, crumb, aroma, flavor, texture, crunch, taste and overall acceptability of FDP were effected significantly with the different storage periods. The cumulative statistical mean values of sensory evolution data of FDP at different storage interval is presented in Fig. 1. The mean values presented in Fig. 1 are the mean values of fresh zero day and 60 days storage periods. The comparison of the storage means demonstrated that the highest scores were given to the pizzas prepared at zero day which could be considered as control as compared to the 60 days storage and results also indicate that there was a significant decrease in the scores for overall acceptability of the frozen dough pizzas with the increase in the storage periods. There was a significant decrease in all the parameters of the pizzas with the increase in the storage periods but the pizzas prepared from frozen doughs containing 2% sorbitol and mannitol remained acceptable for longer periods, due to the treatment affect, as compared to the pizzas prepared from control frozen doughs. The results regarding the storage of frozen pizza dough quality deterioration found in this study also match with the findings of Wolt and D Appolonia (1984), Berglund and Shelton (1993) and Inoue and Bushuk (1996) according to them quality of frozen dough bakery products deteriorates during increasing storage periods. Similarly, Kamel and Manji (1986) studied effect of frozen storage on different pizza formulation and reported the same finding that extended storage caused gradual deterioration in the overall acceptability of pizza. Conclusion The results for the empirical rheological properties of commercial wheat flour and undeveloped pizza dough by the farinographic and mixographic measurements showed that there is an increase in the water absorption level in the dough by the addition of different levels of polyols as they act as humectants and water binding agents in the food products. Use of sorbitol and mannitol as functional ingredients in the frozen dough pizza at the level of 2% each could be a good potential frozen pizza dough improvers as they help to improve the taste, flavor and overall acceptability of pizzas

Effect of Polyols on The Rheological and Sensory Parameters of Frozen Dough Pizza 787 made from frozen doughs during prolong frozen period of times. Acknowledgments The Authors are greatly indebted to Mr. Saqib Ayaz Restaurant General Manager, Pizza Hut Pakistan for technical support and supply of commercial wheat flour for making of frozen dough pizzas during this study. References AACC. (2000). Approved Methods of the American Association of Cereal Chemists. The American Association of Cereal Chemists Inc., St. Paul, Minnesota, USA. Asghar, A., Anjum, F.M., Butt, M.S., Tariq, M.W. and Hussain, S. (2007) Rheological and storage effect of hydrophillic gums on the quality of frozen dough pizza. Food Sci. Technol. Res., 13(2), 96-102. Asghar, A., Anjum, F.M. and Allen, J.C. (2011) Utilization of dairy byproduct proteins, surfactants, and enzymes in frozen dough. Crit. Rev. Food Sci. Nutr., 51(4), 374-382. Asghar, A., Anjum, F.M., Allen, J.C. and Daubert, C.R. (2009). Effect of modified whey protein concentrates on empirical and fundamental dynamic mechanical properties of frozen dough. Food Hydrocolloids, 23, 1687-1692. Berglund, P.T. and Shelton, D.R. (1993). Effect of frozen storage duration in firming properties of breads baked from frozen doughs. Cereal Foods World, 38, 89-90. Farooq, A. (1996). Effect of Polyols (Glycerol and Sorbitol) on The Quality and Shelf Life of Bread and Chapatti Prepared From Local and Imported Wheats. M.Sc. Thesis, Department of Food Technology, University of Agriculture, Faisalabad, Pakistan. Friedman, T.M. (1978). Sorbitol in bakery products. Baker s Dig., 52(6), 10-14. Griffin, C.Wm. and Lynch, M.J. (1968). Polyhydric Alcohols. Hand Book of Food Additives. (Furia, E.T. Ed.) The Chemical Rubber Co., Ohio, USA. Hase, S., Kawamura, U. and Yasui, T. (1981). Effect of sugar and sugar alcohols on the gelatinization and retrogradation of starch. Report of the National Food Research Institute Japan, 38, 73-84. Heaton, K.C.F., Robinson, F. and Lewin, M. (1980). Sorbitol. IFST Proceedings, 13(3), 157-166. Inoue, Y. and Bushuk, W. (1991). Studies on frozen doughs.1. Effects of frozen storage and freeze thaw cycles on baking and rheological properties. Cereal Chem., 68, 627-631. Inoue, Y. and Bushuk, W. (1996). Effects of freezing, frozen storage, and thawing on dough and baked goods. p. 367-400 in: Freezing Effects on Food Quality. L.E. Jeremiah, ed. Marcel Dekker: New York. Kamel, B. and Manji, B. (1986). Effect of frozen storage on different pizza formulations. Cereal Foods World, 31(10), 751-755. Land, D.G. and Shepherd, R. (1988) Scaling and Ranking Methods in Sensory Analysis of Foods. J.R. Piggot. ed. Elsevier Applied Science, New York, pp.155-185. Larsen, D.M., Setser, C.S. and Faubion, J.M. (1993). Effect of flour type and dough retardation time on the sensory characteristics of pizza crust. Cereal Chem., 70(6), 647-650. Lorenz, K. and Kulp, K. (1995). Freezing of doughs for the production of bread and rolls in the United States. p135-153 in; Frozen and Refrigerated Doughs and Batters. Kulp, K., K. Lorenz, and J. Brummer, ed. Am. Assoc. Cereal Chem. St, Paul, Minnesota. Marston, P.E. (1978). Frozen doughs for bread making. Baker s Digest, 52(2), 18-20, 37. Rayas, P. and Uriyapongson, J. (2000). Effect of mannitol in frozen dough quality. Annual meeting AACC 2000. Food & Agricultural Products Center, Oklahoma State University, Stillwater, USA. Spooner, T.F. (1993). The Pizza Process. Baking and Snack, 15(5), 40-43. Steel, R.G.D., Torrie, J.H. and Dickey, D. (1997). Principles and Procedures of Statistics. A Biometrical Approach, 3 rd ed. McGraw Hill Book Co Inc. New York. Stauffer, C.E. (1993). Frozen dough production. In Advances in Baking Technology. Kamel, B.S. and Stauffer, C.E. (ed.). Chapman & Hall. London. Suhendro, E.L., Waniska, R.D, Rooney, L.W. and Gomez, M.H. (1995). Effect of polyols on the processing and qualities of wheat tortillas. Cereal Chem., 72(1), 122-127. Wolt, M.J., and D Appolonia., B.L. (1984). Factors involved in the stability of frozen dough. 1. The influence of yeast reducing compounds on frozen dough stability. Cereal Chem., 61, 209-212.