Effects of temperature and time on clarification of sweet sorghum juice

Raw sweet sorghum juice from three different sources was heated in four different jars. The jars identified as "A" through "D" were heated to 26.7°C, 46.1°C, 65.6°C, and 85°C respectively. Jar A served as the control. At the beginning of the experiment (time = 0 minutes), a juice sample was withdrawn from each jar and stored. The tempera-tures of jars B, C, and D were then raised and maintained respectively at 46.1°°C, 65.6°C, and 85°C. Juice samples were subsequently withdrawn from the top, middle, and bottom portions of each jar at 30-, 60-, and 90-minute intervals. The acidity (pH), percent total soluble solids (PTSS), percent total solids (PTS), and percent total ash (PTA) content of each with-drawn juice sample were measured. The data obtained were evaluated by statistical procedure to determine if temperature and time had any effect on clarification of sweet sorghum juice. Based on the statis-tical analysis of this study, the following inferences can be made: 1. Temperature and time do affect the clarification of sweet sorghum juice. Physical observation of the experimental units showed that when a jar of raw sorghum juice was heated, much of the impurities was coagulated. Part of the coagulated material precipitated to the bottom and part rose to the surface thus leaving the middle portion fairly well clarified. The statistical analysis revealed that after this coagulation period (which was about 30 minutes), the clarification process was no longer temperature dependent. 2. Temperature and time affect color formation in sweet sorghum juice. 3. The acidity (pH) of a heated sweet sorghum juice is the same at all sections of the container. However, percent total soluble solids (PTSS), percent total ash (PTA), and percent total solids (PTS) of heated sweet sorghum juice (and possibly of other heated natural juices) at the top, middle, and bottom sections of the container at a given temperature and time (where tem and t represent temperature (°C) and time (minutes) respectively) can be predicted with the following equations: At the top section (Location 1)-- Percent total soluble solids (PTSS) = 27.698 - 33.47 x 10^-2 tem + 6.5 x 10^-3 t - 11.17 x 10^-7 tem t + 2.62 x 10^-3 tem² + 1.8 x 10^-4 t² - 64.35 x 10^-7 tem³ - 35.27 x 10^-7 t³ + 79.96 x 10^-10 tem t³ Percent total ash (PTA) = 0.3602 + 2.9 x 10^-2 tem + 74.13 x 10^-9 tem^-2 - 21.71 x 10^-8 tem² t - 48.11 x 10^-9 tem³ + 11.06 x 10^-10 tem³ t + 15.6 x 10^-13 tem³ t² Percent total solids (PTS) = 30.556 - 35.59 x 10^-2 tem - 1.64 x 10^-2 t + 1.68 x 10^-4 tem t - 75.92 x 10^-9 tem t² + 2.69 x 10^-3 tem² - 22.36 x 10^-5 t² - 64.56 x 10^-7 tem³ + 24.3 x 10^-7 t³ At the middle portion of the jars (Location 2)-- Percent total soluble solids (PTSS) = 29.6426 - 36.42 x 10^-2 tem - 10.44 x 10^-3 t - 11.2 x 10^-7 tern t + 26.92 x 10^-4 tem² + 36.8 x 10^-5 t² - 64.35 x 10^-7 tem³ - 35.27 x 10^-7 t³ + 79.96 x 10^-10 tem t³ Percent total ash (PTA) = 0.3602 + 2.91 x 10^-3 tem + 14.83 x 10^-8 tem² - 21.71 x 10^-8 tem² t - 48.11 x 10^-9 tem³ + 1.11 x 10^-9 tem³ t + 1.56 x 10^-12 tem³ t² Percent total solids (PTS) = 30.738 - 36.15 x 10^-2 tem - 3.28 x 10^-2 t + 1.69 x 10^-4 tem t + 2.69 x 10^-3 tem² - 1.8 x 10^-4 t² - 75.92 x 10^-9 tem t² - 64.56 x 10^-7 tem³ + 24.3 x 10^-7 t³ At the bottom section of the jars (Location 3)-- Percent total soluble solids (PTSS) = 31.584 - 30.07 x 10^-2 tem - 2.75 x 10^-2 t - 1.12 x 10^-6 tem t + 2.77 x 10^-3 tem² + 5.52 x 10^-4 t² - 6.43 x 10^-6 tem³ - 3.53 x 10^-6 t³ + 79.96 x 10^-10 tem t³ Percent total ash (PTA) = 0.3602 + 2.9 x 10^-3 tem + 2.22 x 10^-7 tem² - 21.71 x 10^-8 tem² t - 4.81 x 10^-8 tem³ + 1.11 x 10^-9 tem³ t + 1.56 x 10^-12 tem³ t² Percent total solids (PTS) = 30.920 - 36.71 x 10^-2 tem - 4.93 x 10^-2 t + 16.88 x 10^-5 tem t + 26.94 x 10^-4 tem² - 13.68 x 10^-5 t² - 75.92 x 10^-9 tem t² - 64.57 x 10^-7 tem³ + 2.43 x 10^-6 t³ For all the equations, tem and t represent temperature and time respectively. The 3-dimensional graph and contour maps plotted with these equations are presented in Figures B-1 through D-6 in the Appendix.