Studies on Shape, Volume and Size of Suspended Pulp in Cloudy Juice Prepeared from Satsuma Mandarin (Citrus Unshiu MARC.) Fruits

Abstract

This research was conducted to determine the shape, the total volume of pulp and volume, size distribution and p value (assumed average particle size) of sample′s pulp over 0.05mm in minimum size in cloudy juice taken from each process in the chopper pulper or In-Line juice extractor systems of A, B and C juice plants and to investigate changes in these volumes and values viz. each juice extraction system at these plants.
(1) It was possible to separate pulp over 0.05mm in size into ten fractions according to size by the use of washing, and ten testing sieves with 20, 35, 60, 100, 145, 170, 200, 250, 280 and 300 mesh openings. P value was estimated through the results of this sieving process.
(2) Pulp separated over 0.05mm in size was neither uniform nor regular in shape. Under the miscroscope, many pulp particles exhibited the pericarp in pieces which were torn, had ragged edges, or rectangular form. The shapes produced by the chopper pulper process displayed more torn shapes than those of the In-Line juice extractor process.
(3) The total volume of pulp, the volume and p value of pulp over 0.05mm in size were 700, 550 and 750ml, 454, 502 and 546ml, 0.74, 0.86 and 0.72mm from the chopper pulper process and 500, 650 and 450ml, 438, 478 and 372ml, 0.85, 0.89 and 0.76mm from the In-Line juice extractor process, respectively. There were differences in these values between both systems. Compared to the volume of In-Line juice extractor process the total volume of pulp and the volume of pulp over 0.05mm in size from the chopper pulper process were large but the p value from the In-Line juice extractor process was larger than for the chopper pulper process. These volumes and values with the pulper finisher process in both system were 350, 275 and 350ml, 233, 226 and 234ml, 0.22, 0.32 and 0.28mm and 256 and 250ml, 196 and 180ml, 0.27 and 0.24mm, respectively. Although the flow diagram of the C juice plant was different from that of the A and C juice plants, these values were decreased by about 1/2 or 1/3 by this process. By the centrifugal machine, these volumes and values were decreased by 150, 100 and 90ml, 104, 88 and 73ml, 0.15, and 0.14mm, respectively. These volumes and values were decreased by about 1/5.7 compared with the volume and value of the chopper pulper and In-Line juice extractor process. For that reason, it seems that these volumes and values were adjusted by the pulper finisher and the centrifugal machine.
(4) When straight juice was prepared by hand Reamer juice extractor from six Citrus Unshiu fruits cultivated in different districts there were large differences in the total volume of pulp over 0.05mm in size. It was recognized that these volumes and values were affected by the properties of the raw material.