UNIVERSITY OF CALIFORNIA • COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY 4, CALIFORNIA THE PREVENTION OF MECHANICAL INJURY DURING TRANSIT OF NEW-CROP POTATOES W. R. BARGER. E. V. SHEAR, 3 and L L. MORRIS* The prevalence of injuries in new-crop White Rose potatoes from California has caused comment and concern in the eastern markets. These in- juries not only impair the quality of the pota- toes affected, but also cause spotting of the bags and lowering of the sales value of the whole consignment. The greatest injury occurs in the bags resting on the floor racks, but a lesser amount is found throughout. The potatoes in the bottom layer represent one sixth to one fifth of the load, and any improvement in their condition at arrival would have a definite effect on the total value. During the 1943 and 1844 seasons, transit tests were originated in Kern County, California, in an attempt to evaluate the use of padding material on the floor racks of potato cars. In 1944, the amount of damage evident in unprotected bags was recorded upon their arrival at New York City. Observations also were made concerning the amount of injury apparent at loading time. Under present marketing conditions floor pads apparently more than pay for themselves by re- ducing the amount of crushing and bruising of potatoes in transit. Many small bruises were found before shipping. The extent to which these affect the condition on arrival was not deter- mined; but, since bruises occur, frequent inspec- tion of packing-house equipment and insistence on careful handling by all operators might aid in preventing some of the damage that the pota- toes show upon arrival. There is evidence that the "3x5" load, commonly used in California, does not carry so well as the pyramid-type load. The potatoes used in these tests were U.S. No. 1 White Rose, fairly mature. For most of the tests, the washed potatoes were packaged in •'■Part of a cooperative investigation of methods of handling and shiDping truck crops, conducted by the U.S. Department of Agriculture and the California Agricultural Experiment Sta- tion. 2 Associate Physiologist, Bureau of Plant In- dustry, Soils, and Agricultural Engineering, U.S. Department of Agriculture, Fresno, Cali- fornia. 3 Associate Pathologist, Bureau of Plant In- dustry, Soils, and Agricultural Engineering, U.S. Department of Agriculture, New York, New York. 4 Assistant Professor of Truck Crops and Assistant Olericulturist in the Experiment Sta- tion. medium-weight burlap bags, holding 100 pounds each. A few shipments contained bags made of cotton sheeting. The cars were initially iced to capacity at Bakersfield after loading and were usually re-iced twice during transit (rule 247) to Atlantic Coast markets. Loading Methods Transit injury was studied in two types of loads, each containing 360 bags. In the 3x5 load, there were 11 stacks in each end of the car, 3 rows wide and 5 layers high, with all bags laid crosswise of the car (fig. 1). The doorway provided space for 30 bags, set in 2 Fig. 1 . - -Arrangement of a 36,000-pound 3 X 5 load. There are 11 stacks in each end of the car, plus 30 bags in the doorway. Note that the bottom bags rest on their edges and are therefore subject to rocking in transit. crosswise rows. During were moved into the cars a hand truck. Each pile (without rehandling) by forward from the truck, on edge on the truck so tipped forward more easi operation; it remained i car. These bags on edge in transit which action erable abrasion of the p floor rack. Ll] UNIVERSTT ■-- 3FC; rF I | COLLEGE u, AGRICULTURE DAVIS loading, the potatoes in piles of 5 bags on was placed in the car tipping or bumping it The bottom bag was set that the pile could be ly during the loading n this position in the tended to roll or rock could result in consid- otatoes next to the The pyramid load consisted of 5 double stacks of 30 or 31 bags each, arranged in both ends of the car. (A stub stack of 5 bags may be placed upright at each bunker making the load slope away from the doorway.) The 50 to 60 bags left over were put in two rows in the doorway. Fig. 2 . --Arrangement of a 36,000-pound pyramid load. There are 5 double stacks in each end of the car, plus 50 bags in the doorway. Note that the bottom bags rest flat. The arrangement of the bags within a double stack is shown in figure 2. The bags for the doorway rows were laid crosswise of the car. Since each bag is handled separately, this load requires more labor than the 3x5 load; but the bags can be set firmly in place to minimize rocking in transit. Description of Pads In most of the tests, the floor pads were of matted excelsior enclosed in paper sleeves. They were about 1/2 inch thick, 12 inches wide, and 30 inches long, large enough to accommodate one bag laid flat. When laid in the car, they were spaced to permit circulation of air up through the floor rack. Pads filled with pulped paper proved just as effective as excelsior pads. They were about 3/8 inch thick, 12 inches wide, and 96 inches long. These long pads were laid lengthwise of the floor, singly or in double-width strips, whichever method was needed to protect the floor face of the bags. Space was left between each double row of pads to permit air circulation up between the rows of bags. Inspection of Potatoes 'When the cars were unloaded, the potatoes were examined for injury and decay. The entire contents of several bags were scored. Cutting the bag so that the tubers were examined in about the same position that they occupied during transit gave an accurate picture of the occur- rence of floor bruising. Deep injury included crushing, severe bruising and cracking (fig. 3), and other forms of deep mechanical injury. Near- ly half the potatoes arriving with deep injury were unsalable. Shallow injury included bag marks or imprints of the bag material, slight bruises, and browned or discolored spots result- ing from pressure or from rubbing against other potatoes in transit (fig. 4). Potatoes with shallow injuries were salable but, obviously, had lost some of their market quality. The browned spots here reported do not include the defect known as surface browning or wind injury. Browned spots caused by bruising occur on all parts of the tuber; they show evidence of pres- sure or rubbing, whereas surface browning after wind injury is found only on previously skinned areas. The decay encountered was mostly soft rot. Occasionally it was in an incipient stage, causing only slimy pits in the skin; but usually it was advanced, spreading slime and ooze to adjacent tubers. Injury and decay were expressed as per cent of the number of potatoes per bag; the percent- ages given in the tables are averages for the bags representing a given treatment. Statisti- cal significance between averages was determined by the usual "t-test." Survey of Loads Not Protected by Floor Pads Inspection, at the market, of bags not pro- tected by floor pads showed (1) that most injury occurred in the bottom-layer bags; (2) that a fairly large number of potatoes were severely injured in transit; (3) that potatoes probably carry better in pyramid loads than in 3x5 loads (table 1). The potatoes in this survey were ob- tained from 15 cars at the time of unloading. Although the maturity of the various lots is not shown in the table, at arrival the browned spots and possibly some deeper injuries and decay were less in the more mature tubers — a fact indicat- ing the importance of maturity for sound de- livery. With both methods of loading, the amount of deep injury was significantly greater in the bottom layer than in the rest of the load. Deep injury averaged 7.9 per cent in the bottom layers of the pyramid loads, as compared with 2.5 per cent in the middle and top. With the 3x5 type, there was an average of 17.3 per cent deep injury in the bottom layer as compared with 2.4 per cent in the middle and top positions. In both types of loads, the average amount of shallow injury was also significantly greater in the bottom layer. These observations suggest the value of protecting the bottom with padding material. In the 3x5 load, many floor bags were found [2] 1 Fig. 3. --Types of transit damage classed as deep injury in this report. These were from bottom-layer bag that was not protected by floor pads'. \ f f Fig. k- --Types of transit damage classed as shallow injury in this report, to have rolled completely over in transit, floor- rack abrasions of bags and tubers being found on the top face of bags at the time of unloading. Comparisons between the two types of loads show a significantly greater amount of deep injury in the floor layer of the 3 x 5 load than in that of the pyramid. Shallow injuries such as browned spots and bag marks were not, however, signifi- cantly different in the floor layers of the two types of loads. As is to be expected, the two systems of loading were alike in the relatively small amount of injury occurring in the upper layers of bags. Decay in these cars ranged from to 3 per cent, averaging less than 1 per cent. In both types of loads, decay averaged slightly higher in the middle and top than it did in the floor layer, probably because transit temperature was higher in the upper part of the car. Although this difference proved to be statistically sig- nificant in the pyramid loads and not so in the 3x5 loads, the differences were too slight to have any practical importance. There were no significant differences in decay attributable to the type of load. Decay was much more objectionable than is in- dicated by the amount shown in the table; the decayed tubers leaked slime and ooze throughout the bag and over adjacent bags, causing wet spots and covering sound potatoes with foul-smelling bacterial ooze. The receiver attempted to re- fuse several cars because of the slimy, smelly condition indicative of excessive decay; he ac- cepted them only after the actual amount of decay was shown to be small. Pretransit Injuries The removal of all injured tubers from the bags to be used in pad tests gave an estimate of the amount of pretransit injury occurring at three packing houses. Mechanical injuries such as cuts, cracks, and deep bruises were encounter- ed in 1.5 to 2 per cent of the potatoes sorted (table 2). About 5 to 7 per cent showed bruis- ing. Although many of the cuts and bruises were too small to be scored against the grade, the amount found may indicate rough handling or it may indicate poorly adjusted equipment. The amount of pretransit injury in individual bags varied considerably, but averaged about the same at each of the three packing houses. Removal of pretransit injuries at the packing house did not always improve the condition of the potatoes arriving at the market. Because of the variable amount of injury received in transit, some bags that had been free of injury before loading arrived with more injury than bags that were not re-sorted. The removal of injured potatoes from the test bags before ship- ping gave assurance, however, that the injury observed at unloading had occurred in transit or during the loading operation. Effectiveness of Floor Pads in Preventing Injury During 1944, the effectiveness of padding material was tested in 5 cars delivered to New York City and vicinity. Three of these loads were of the 3x5 type, and 2 were of the pyramid type. Floor pads were used under half the load in each test car. Upon arrival at the market the amount of injury, especially in the bottom bags, was much greater in the bare halves of the cars than in the padded halves (table 3). Test bags of injury-free potatoes were shipped in the bottom and middle layers at the quarter-length position in the bare and padded halves of each car. Injury was excessive in the bare halves, regardless of the type of load used; it apparently resulted from the constant jolting received en route. Some of the cars had splintered floor racks, and in others the load shifted in transit; but apparently neither of these conditions caused any more injury than the constant jolting to which all cars were sub- jected. Deep injuries observed at the market were significantly less in the padded halves of the cars than in the unprotected halves. This was true for both floor and middle positions. The shallow-type injury occurring in the floor layer was also lessened by the use of the pads. Al- though pads apparently reduced shallow injury in the middle layer, the difference did not prove to be significant. The cushioning effect of the pads was also shown by the fact that fewer holes were rubbed through the bags in transit. In one test, 70 per cent of the bags in the bottom layer of the bare half of the car arrived with holes, com- pared with 10 per cent in the padded half. In preliminary tests during the 1943 shipping season, floor pads were used experimentally in 14 cars. Most of the loads were diverted to army camps or to markets where the receivers failed to report the condition on arrival. Re- ports from receivers of 5 of the cars indicated, however, that floor damage affected 3 to 35 potatoes per bag in the bare halves of the cars, and from to 7 potatoes per bag in the padded halves. Transit Temperatures of Padded Loads Transit temperatures in padded cars gave no indication that the pads interfered with the circulation of air through the load (table 4) . Recording thermometers were placed in bags in the bottom and middle layers in the padded and bare halves of test car 11 en route to the New York area, Hay 17 to June 1, and in bottom-layer bags of test car 12 en route May 23 to June 3. The cars were loaded dry, iced to capacity at Bakersfield after loading, and re-iced twice in transit (rule 247) at West Laramie, Wyoming, and Chicago, Illinois. According to Weather Bureau [4] TABLE 1 Comparison of Arrival Condition of White Rose Potatoes Shipped in Two Types of Loads from Kern County, California, to the New York Area, 1944 Test no. Loading station Per cent of deep in. jury Date unloaded Bottom layer* Middle and top layersf Per cent of shallow injury Bottom layer* Middle and top layersf Per cent of decay Bottom layer* Middle and top layers f Pyramid type of loading 1 Di Giorgio May 15 5.2 0.6 5.5 6.5 0.4 0.8 2 Di Giorgio May 17 6.2 2.4 12.6 4.5 0.1 0.9 o Di Giorgio May 18 9.6 2.7 14.5 7.0 1.2 1.2 4 Di Giorgio May 20 5.5 3.0 7.3 4.1 0.5 0.4 5 Di Giorgio May 22 5.6 0.4 7.1 2.0 0.6 0.6 6 Di Giorgio May 27 4.3 2.0 3.1 2.7 0.0 0.3 10 Di Giorgio May 29 6.1 3.0* 3.1 0.0* 0.1 0.0* i3§ir Di Giorgio June 4 6.8 6.9* 5.6 0.2* 0.0 0.1* 15 §11 Di Giorgio July 7 21.6 1.9* 26.2 3.5* 0.0 0.2* 3x5 typ e of loading 7 Edison May 27 20.8 1.9 4.3 0.2 0.0 0.0 8 Shafter May 27 15.7 0.3 4.3 0.8 0.0 0.0 9 Patch May 29 9.9 0.9* 7.5 3.0* 0.2 0.4* 11§1 Patch June 1 16.6 3.3* 13.3 1.1* 0.0 0.0* 12 § Patch June 3 11.0 3.9* 9.3 7.8* 2.3 3.2* 14 § Shafter June 21 30.0 4.0* 3.9 5.1* 0.1 0.4* Average of nine pyramid loads .... 7.9 2.5 9.4 3.4 0.3 0.5 Average 17.3 2.4 7.1 3.0 0.4 0.7 ♦Average of 4 to 6 bags. t Average of 2 to 3 bags in middle j_ayer and same number in top layer. * Average of 2 and 3 bags, top layer only. ^Regularly graded bags from unpadded half of car. IlLoad shifted in transit. IlLoad slightly shifted. TABLE 2 Pretransit Injury in U.S. No. 1 White Rose Potatoes at Three Packing Sheds in Kern County, California, June 1944 Loading Number of sacks inspected Average number of tubers per sack Per cent of mechanical injury* Per cent of slight bruises station Range Average Range Average Patch Shafter Di Giorgio 8 8 8 266 289 187 0.4 - 3.6 1.3 -2.9 0.5 -2.9 2.0 1.9 1.5 1.9 - 8.9 3.6 -11.7 5.8 - 8.6 5.1 6.9 6.7 ^Including cuts, cracks, and deep bruises. [5] TABLE 3 Arrival Condition of Padded and Nonpadded Test Bags of White Rose Potatoes; Visible Injuries Removed Before Loading Test Treat- ment Condition of floor rack* Shifting of load Per cent of deep injury- Per cent of shallow injury Per cent of decay no . Bottom layer t Middle layer i Bottom layerf Middle layer $ Bottom layert Middle layerf Pyramid, type of load ing 13 Bare Fair Severe 10. 5§ 5.9 3.9§ 1.7 0.4§ 0.3 13 Padded Fair Severe 4.6§ 4.8 1.6§ 2.1 0.2§ 0.3 15 Bare Poor Slight 16.0 5.3 22.4 7.4 0.2 0.5 15 Padded Poor Slight 13.2 2.4 18.9 7.1 0.0 1.21 3x 5 tyj e of loading 11 Bare Poor Severe 20.9 8.0 15.3 8.0 0.0 0.0 11 Padded Poor Severe 9.3 3.1 13.7 2.2 0.0 0.0 12 Bare Fair None 10.2 4.6 9.4 2.4 0.7|| 2.7 12 Padded Fair None 2.6 3.5 5.7 1.4 0.1** 3.5 14 Bare Poor None 21.3 6.8 3.9 0.4 0.2 l.ltt 14 Padded Poor None 16.0 1.4 2.8 0.4 0.1 0.7 Average for bare 15.8 6.1 11.0 4.0 0.3 0.9 Average for padde d . . . . 9.1 3.0 8.5 2.6 0.1 1.1 *With respect to splintered and rough floor boards. t Average of 3 bags. I One bag inspected. § Average of 2 bags. U Three other bags averaged 0.3 per cent decay. I Three other bags averaged 2.3 per cent decay. **Three other bags averaged 2.5 per cent decay. ttThree other bags averaged 0.2 per cent decay. TABLE 4 Temperatures in Bags of Potatoes in Bare and Padded Halves of Cars During Transit* Position Treat- ment Temperature, degrees Fahrenheit, at indicated days in transit in car 1 2 3 4- 5 6 7 8 9 10 11 12 13 14 15 Test 11 Bottom Bare 57 43 40 39 38 37 37 37 37 37 37 37 37 37 37 37 Bottom Padded 57 44 40 39 38 37 36 36 38 38 38 38 38 38 38 38 Middle Bare 59 56 49 45 43 42 41 41 40 40 40 40 40 40 40 40 Middle Padded 58 55 50 46 45 44 42 42 41 40 40 40 40 40 40 40 Test 12 Bottom Bottom Bare Padded 60 60 48 54 41 45 40 42 40 41 40 42 38 41 39 39 40 40 41 40 40 40 40 40 *Cars initially iced at Bakersfield after loading- and re-iced twice en route -- West Laramie Wyoming, and Chicago, Illinois. [6] records along the Southern Pacific and Union Pacific lines, the outside temperature between Bakersfield and Chicago ranged between 40° and 66° F at night and 60° to 85° during the day. Upon arrival at Jersey City, New Jersey, the bunkers of the cars were 1/3 to 3/5 full of ice. With this method of icing, the bottom-layer bags (originally about 60°F) cooled to about 40° in 2 to 3 days, and the middle layer to about 45°. During the latter part of the trip, bottom and middle layers were 37° and 40° respectively. Transit temperatures were practically the same in the padded and bare halves of the cars, a fact showing that refrigeration and air circula- tion were not obstructed by the pads. Similar results were obtained with two test cars shipped to Chicago and New York City in May, 1943. Commercial Considerations In shipping tests during two crop years, the use of floor pads materially reduced bruising and other injury received in transit. Not only did the pads reduce the amount of floor damage, but apparently their cushioning effect extended up through the load and resulted in less injury, less bag marking, and fewer worn holes in the upper layers as well. Apparently there is enough jolting in transit to cause excessive bruising in nonpadded cars even when there is no evidence that the load shifted en route. Floor pads in transit kept enough potatoes from being crushed or from otherwise being made worthless by severe bruising to justify fully the cost of using them. In these tests, it was estimated that the floor pads affected savings of 1 to 4 bags of potatoes per car. The effect of this amount of injury up- on the wholesale price would depend on many fac- tors. However, the fact remains that the use of floor pads would result in the delivery of more salable potatoes to the retail market. Inspection at packing houses before the pota- toes were loaded into the cars showed less than 2 per cent mechanical injury severe enough to be scored against grade; but there were many small, shallow injuries and minor pressure bruises. The extent to which these slight pre- transit injuries caused deterioration in transit was not determined. Obviously, however, more careful handling and better adjustment of mechani- cal equipment used would tend to eliminate such -injuries and to improve the grade at the market. Comparisons of nonpadded 3><5 loads with pyramid loads indicate that less floor damage occurs in the latter. In the pyramid load, more care is required in placing the bags, and the bottom-layer bags rest flat on the floor, making a broad, solid base for the pile above. The same careful placing of the bottom bags, together with hand loading, probably would improve the 3x5 load over the present method of "bumping" the stacks into place. Careful handling of the bags in the car should not be overlooked because , obviously, rough treatment can cause injury re- gardless of the type of load used. Although floor pads were beneficial in all the tests, the greater injury occurring in unprotected 3x5 loads suggests a special need for cushioning ma- terial with this type of load. Acknowledgments Thanks are due to Mr. A. M. Fielding, Pacific Coast representative of the Freight Container Bureau, Association of American Railroads, and to various shippers and receivers for their cooperation; also to the American Excel- sior Corporation and Jiffy Manufacturing Com- pany, for furnishing the pads. For help in in- specting cars at various markets, appreciation is expressed to representatives of the U.S. De- partment of Agriculture Inspection Service, the Western Weighing and Inspection Bureau, and the Railroad Perishable Inspection Agency; also to J. S. Wiant, L. D. Ferdland, M. A. Smith, and G. B. Ramsey, Bureau of Plant Industry, Soils, and Agricultural Engineering, U.S. Department of Agriculture. 3m-November, '45(63161 [V] ' Digitized by the Internet Archive in 2012 with funding from University of California, Davis Libraries http://archive.org/details/preventionofmech61barg