Viscoelastograph measures and total organic matter test : suitability in evaluating textural characteristics of cooked pasta

Cereal Chem. 70(1):67-72 Two sets of Italian durum wheats were used to make spaghetti: 54 firmness was linked to a different factor. At 900C firmness was associated samples dried at low temperature (500C) and 64 samples dried at high with stickiness, bulkiness, and SJ on the second factor, whereas TOM temperature (90° C). Cooking quality was evaluated using sensory judgshifted to another factor. Multiple regressions were calculated to evaluate ment (SJ), total organic matter (TOM), and viscoelastograph parameters. the relative worths of stickiness, bulkiness, and firmness on SJ and TOM SJ was expressed by its components (stickiness, bulkiness, and firmness) as well as their relationships with viscoelastograph measures when different and by an overall score. Factor analysis was applied as a clustering tool drying temperatures were applied. At low temperature, stickiness was to assess similar behavior of variables. Four factors were useful in the most important SJ component and TOM was a suitable method in describing the relationships among variables for each temperature estimating SJ. At high temperature, firmness played a more important considered. At 50° C the first factor was related to viscoelastograph paramrole and viscoelastograph consistency was used to complement the TOM eters, the second grouped SJ, stickiness, bulkiness, and TOM, whereas test. Textural characteristics of cooked pasta are of primary importance in defining pasta quality. Among the characteristics, firmness, compressibility, elasticity, and surface stickiness have received the greatest attention, and different objective methods have been used to measure these parameters (Matsuo and Irvine 1969, 1971, 1974; Feillet et al 1977; Voisey et al 1978a,b; D'Egidio et al 1982; Dexter et al 1983, 1985). Matsuo and Irvine (1969, 1971) developed a Grain Research Laboratory (GRL) tenderness 'Istituto Sperimentale per la Cerealicoltura, Via Cassia 176, 00191 Rome, Italy. @1993 American Association of Cereal Chemists, Inc. testing apparatus to measure tenderness, compressibility, and recovery of cooked pasta. Voisey and Larmond (1973) studied the relations between sensory parameters and instrumental measures obtained from Instron and Ottawa measuring systems. Subsequently, Matsuo and Irvine (1974) reported the good relationships of GRL apparatus readings with the sensory evaluations obtained by Voisey and Larmond (1973). Dexter et al (1983) adapted the GRL tester to measure cooked spaghetti stickiness, and then Dexter et al (1985) found their instrumental measures well related to the total organic matter (TOM) test of D'Egidio et al (1982). Feillet et al (1977) applied the viscoelastograph to the determination of viscoelastic properties of cooked Vol. 70, No. 1, 1993 67 pasta. This is a routine method used by the Institut National de la Recherche Agronomique (Montpellier, France) to estimate pasta quality, jointly with evaluation of surface properties obtained by reference photographs. The viscoelastograph is easy to use and widely employed, but no correlation between viscoelastograph parameters and sensory textural characteristics have been reported. As sensory analysis is usually considered the reference method to judge the suitability of any objective measure, this work was performed 1) to compare viscoelastograph parameters and the TOM test with sensory judgment (SJ) and 2) to define the relative importance of these parameters on SJ when different temperatures for drying pasta are used. MATERIALS AND METHODS Plant Material Two different sets of durum wheats were considered. The first one was composed of 54 samples obtained from 30 varieties grown at three locations in Italy during 1989; 16 varieties were the same in all three environments. The second set was of 64 samples obtained from 30 varieties grown during 1990 at three locations different from those of 1989; 10 varieties were the same in all three locations. Four varieties were common in the two sets; therefore, 56 varieties representative of the main Italian durum wheats were considered. All of the samples (n = 118), grown in experimental trials, were analyzed separately and were of pastamaking grade. Spaghetti from the 54 samples of 1989 was dried at low temperature (50'C) and that from the 64 samples of 1990 was dried at high temperature (900C). The samples of the first set, dried at 500C, had the following average grain characteristics: test weight = 78.9 kg/hl (range: 77.3-81.0 kg/hl), ash = 2.0% dm (1.86-2.26%), SDS sedimentation test = 34 ml (20-49 ml), alveogram W= 167 j10-4 (50-297 j10-4), and protein content = 13.3% dm (10.7-17.4%). For samples of the second set, dried at 900 C, the grain characteristics were as follows: test weight = 80.4 kg/hl (range 78.2-83.5 kg/hl), ash = 1.86% dm (1.66-2.00%), SDS sedimentation test = 43 ml (18-55 ml), alveogram W= 156 JIO0-4 (43-302 j_10-4), and protein content = 14.7% dm (12.6-17.4%). Analytical Test Grain protein content was determined by the Kjeldahl method (percent N X 5.7, dm basis). Technological Tests Wheat (25 kg) was cleaned, conditioned to a water content of 16%, and left to moisten overnight. Standard milling was performed in a Buhler MCK mill (Buhler, Uzwil, Switzerland) with three breaking and three sizing passages. The normal semolina yield reached a value of approximately 70%. The semolina was mixed with tap water to obtain a total dough water content of 32-33%. The dough was processed into spaghetti