PH RELATION WITH THE RHEOLOGICAL ANALYSIS RESULTS

Transcription

1 PH RELATION WITH THE RHEOLOGICAL ANALYSIS RESULTS 1 Amauri Anzolin Viecili¹ Tatiane Pauly² Fernanda Jaqueline Menegusso¹ Felipe Zanetti¹ Dermanio Tadeu Lima Ferreira³; ABSTRACT The chemical composition of cereal grains vary widely depending of the environment, soil and wheat variety, the latter is a critical factor for the flour quality. One of the physical analyses considered important to evaluate the productivity and quality of the grain is the hectoliter weight, influenced by uniformity, shape, density, grain size, by the level of foreign matter and broken sample grains, serving as an indicator of grain health. Knowing that many people had the habit of comparing quality and extraction index with the hectoliter weight, analyses of alvegraphy were done, color and Falling Number, determining that there isn t any relation between the rheological results with the ph physical result. Keywords: alvegraphy, comparative analysis, wheat. 1 INTRODUCTION Cereal is considered an important culture in the human nourishment being that wheat, rye, corn, barley, sorghum, oat and triticalli the major ones. Chemical composition of the cereal grains vary widely depending o the environment, soil and variety. Flour type is influenced by the variety of wheat used to produce it, as well as the production process. The variety of wheat is a critical factor for the flour quality. From the commercial point of view, wheat is divided in four big grades: hard, soft, white and durum, being the ph (hectoliter weight) for the spring red hard class 76,2; for the winter red hard class 78,6; for the soft 77,9; for the white 77,3; and for the durum (77,6 kg/hl. (EL-DASH et al.) There are various parameters to qualify wheat grain and the flour produced from it. One of these methods is the hectoliter weight. The hectoliter weight is a physical analysis of the grain, and it is the wheat 100 liter mass expressed in kg/hl. It is influenced by uniformity, shape, 1 Graduando no curso de Agronomia Faculdade Assis Gurgacz; 2 Graduada em Agronomia Faculdade Assis Gurgacz; 3 Dr. Docente da Faculdade Assis Gurgacz

2 density, and grain size and by the level of foreign matter and broken sample grains, serving as an indicator of the grain health (MIRANDA et al. 2008). According to SCHMIDT et al (2005), it was verified that the Hectoliter Weight does not have correlation with the variables analyzed (Protein level in the Grain (Prot. G), Protein level in the Flour, Micro sedimentation (SDS), Alveography (W), Escore gluten 1 (E) and Mixography. This demonstrates that despite the hectoliter weight evaluation be very fast, simple and ordinarily used in improvement programs, it won t be efficient when used in the selection of superior genetic constitutions for the bakery quality. Some authors like Mellado et al (1985) related the rain effect after the wheat maturation over the grain production, hectoliter weight, hardness and the level of protein in the grains, etc, and specifically over the ph, concluded that it is the only variable affected, getting to a reduction of 5% compared with the original one. According to Guarienti et al. (2005, apud Hirano, 1976), rain in the inicial maturation period affect, mainly, quantitative of the grains, while rain at the end of maturation causes lessening in the characteristics of the wheat quality. Rain also provokes germination, and according to Mandarino (1993), the germinated grains, or about to germinate, present amilasic extremely elevated, what reduces the quality of the flour produced, hindering or even obstructing the baking process. This research has as its objectives evaluate the ph values relating them with the wheat flour quality analyses, through physical (color) chemical-physical (Falling Number) and rheological (alveography) analyses. 2 MATERIALS AND METHODS Experimental grinding was done in the pilot mill Vitti Molinos according to the AACC method (1999) through a passing on the breaking system and two passing through the reduction system. Hectoliter weight was determined using a Dalle Molle scale determined according to the Seed Analysis Rules (Brazil, 1992), and results were expressed in kg.hl -1. Falling number in the flour was determined through the used of Perten Instrument Falling Number device according to the AACC method 56-81B (1999) using, in duplicate, seven grams of sample corrected for 14% of humidity. The objective of the Minolta s CR410s Colorimeter was to evaluate flour color by translating this color in numbers according to the AACC method #14-22 (1999). The result was expressed in CIELAB, which is the most used color system to evaluate food coloring, by reading samples for reflectance (Oliveira, 2003). Results are given in L, a* and b*, being L (100 = total White, 0 = total Black), a* (+ = red tendency, - = green tendency), b* (+ = yellow tendency, - = blue tendency). Wheat flour visco-elastic characteristics were determined in a Chopin alveograph - model NG (Villeneuve-la-Garenne Cedex, France) - using the AACC method #54-30 (1999) passing 250 grams of flour and ml of water corrected in base of 14% of humidity. Alveogram parameters were obtained tenacity (P), which measures maximum over pressure exerted in mass expansion (mm), extensibility (L), which measures curve length (mm), and mass

3 deformation energy (W) that corresponds to the mechanical work necessary to expand the bubble up to the rupture - expressed in 10-4 J. After analyses, we submitted the results to regression tests, on Minitab software, from which graphs and linear correlation for each result in relation to Hectoliter weight (PH) were done. 3 RESULTS AND DISCUSSIONS According to Figure 1, which represents calorimetric L results (0 = total black, 100 = total white), one can verify that its results had low correlation with its Hectoliter weight results indicating that ph value is not a determinant factor to obtain a more desirable color with L near 100. Figure 1. L correlation with Hectoliter weight. When we evaluated Figures 2, 3, and 4 - tenacity, extensibility, and power, in that order - we observed that the Hectoliter weight result has no correlation with the Alveography results, so we concluded that it will not influence mass behavior or final flour quality. Figure 2. Correlation between tenacity (P) and Hectoliter weight.

4 Figure 3. Correlation between extensibility (L) and Hectoliter weight. Figure 4. Flour energy (W) correlation with the hectoliter weight.

5 The same is true when Figure 5, which shows the correlation between Falling Number and Hectoliter weight, is analyzed. We observed that there is no correlation that holds a result of R- Sq(adj) with 0.0%, that is, ph value does not correspond to a higher or lower enzymatic activity. Figure 5. Correlation between Falling Number and Hectoliter weight. 4 CONCLUSION

6 According to the obtained results we can evaluate that although wheat is commercialized by the its Hectoliter weight, it has no connection with its rheological characteristics, which indicates that wheat does not depends on its ph to have adequate, quality characteristics for the market. Besides not having influence in the results found by SCHMIDT et al (2005), there is also no correlation with Colorimetry and Falling Number results. 5 BIBLIOGRAPHICAL REFERENCES EL-DASH, A. A.; CAMARGO, C. DE O. ; DIAZ, N. M. Fundamentos da Tecnologia de Panificação. In: Série Tecnologia Agroindustrial. Cap. 6. p GUARIENTI, E. M.; CIACCO, C. F.; CUNHA, G. R.; DEL DUCA, L. DE J. A.; CAMARGO, C. M. DE O. Efeitos da precipitação pluvial da umidade relativa do ar e de excesso de déficit hídrico do solo no peso do hectolitro, no peso de mil grãos e no rendimento de grãos de trigo. Ciência e Tecnologia de Alimentos, v. 25, n. 3, p , GUARINTI, E. M. Qualidade industrial de trigo. 2ª ed. Passo Fundo: EMBRAPA-CNPT, MANDARINO, J M. G. Aspectos importantes para a qualidade do trigo. Londrina: Embrapa - CNPo, Cap. 60, p MELLADO Z.,M.; MALDONADO, I.I.; GRANGER Z. D.; Efecto de la lluvia, posterior a la madurez de cosecha, sobre el grano de trigo. Agricultura Tecnica, Santiago, v. 45, n. 3, p , MIRANDA, M. Z.; MORI, C. De; LORINI, I., Qualidade Comercial do Trigo Brasileiro: Safra, Passo Fundo: Embrapa, OLIVEIRA, J. Metodologias analíticas. Curitiba: Granotec do Brasil, 2003.