Lewis A. Schaper

Carbon dioxide accumulation and flushing in potato storage bins

Carbon dioxide levels were measured in a commercial-size research bin, a model bin, and laboratory chambers during suberization and reconditioning periods. Patterns and magnitudes of CO2 accumulation in the commercial bin differed from those in the laboratory chambers due to wind and locational effects that were present in the bin. Higher accumulations were measured in the chambers than in the storage.

Potato losses during the first three months of storage for processing

This survey attempts to define the range of U.S. potato losses and their causes during the first three months of storage. The sampling of three respondent groups included a local storage region, the processing industry, and the federal inspection service (USDA). Questionnaires indicated 64 to 150 thousand metric tons were annually lost during early storage from the total crop stored for processing. This constitutes a range of 5.6–13.2 million dollars lost in production costs. Mechanical damage, inclement weather, and disease were assigned similar causative rankings for persistent loss in early storage by all three groups; however, synergistic combinations of losscausing factors and geographic differences were also noted.

Horizontal and Vertical Pressure Patterns of Stored Potatoes

ABSTRACT LATERAL and vertical pressures were observed daily during six storage seasons in a 635 metric tons (14,000 cwt) potato storage bin. Comparisons of actual pressure patterns and equivalent fluid density values are given. Variations in wet and dry potato pressure patterns with time and storage activities are shown and discussed. This information should be useful for structural design of potato storages

Mathematical Expressions for Lateral Potato Pressures

ABSTRACT The relationship pressure equals exp [a + B (distance above floor)^^] was developed to estimate lateral pressures for Irish potatoes with wet or dry surfaces for a 5.3 m (17.5 ft) pile height. This applies to bins in which the bin width exceeds the pile depth. When dry surface conditions existed, this relationship more accurately predicted wall reactions and bending moments for simply supported beam conditions than the equivalent fluid density analogy. When wet surface conditions existed, there were no major differences in predicted reactions and moments for either method of representing lateral pressures.

Storage temperature maintenance and its effect on processed potatoes

SummaryA direct-expansion refrigeration system was developed that could operate at 40 F and 85% relative humidity without moisture condensation on the evaporator coil.At low temperatures and high relative humidities, high air flow rates did not increase the rate of weight loss of potatoes after the suberization period. Therefore, high air flow rates that may be required for certain types of refrigeration coils do not appear to have a detrimental effect on potatoes.As judged by the test panel, generally acceptable flakes can be obtained at 40 and 45 F storage with four weeks conditioning at 65 F or at 50 F storage without conditioning. Discounting flake color, check storage temperature produced white flakes most consistently. Flake quality noticeably improved after four months of storage. These results are generally consistent with the results for the 1961 through 1964 crop inclusive (2). The Norgold variety exhibited a poor flake texture throughout the processing period.No consistent weight loss differences occurred at 40 and 45 F storage with conditioning versus 50 F storage without conditioning.Four weeks conditioning at 65 F after storage at 40 and 45 F decreased the reducing sugars to the initial levels that existed at harvest time.ResumenSe desarrolló un sistema de expansión directa de la refrigeración que puede funcionar a 40 F con 85% de humedad relativa sin que se condense la humedad sobre la serpentina del evaporador.Con temperaturas bajas y alta humedad relativa las altas tasas de corriente de aire no aumentaron la tasa de pérdida de peso de las papas después del período de suberización. Por lo tanto, las altas tasas de corriente de aire que pueden necesitar ciertas clases de serpentinas de refrigeración no parecen tener un efecto adverso sobre las papas.En opinión del grupo de prueba se pueden obtener hojuelas generalmente aceptables con almacenaje a 40 y 45 F con cuatro semanas de acondicionamiento en almacenaje a 65 ó 50 F sin acondicionamiento. Descontando el color de las hojuelas los lotes examinados produjeron hojuelas tan buenas como los lotes en condiciones de control. La temperatura de almacenaje a los 50 F produjo más continuadamente las hojuelas blancas. La calidad de las hojuelas mejoró notablemente después de cuatro meses de almacenamiento. Estos resultados son en general congruentes con los resultados de la cosecha de 1961 a 1962 inclusive (2). La variedad Norgold produjo hojuelas de pobre contextura durante el período de procesamiento.No se produjeron diferencias continuadas en la pérdida de peso en almacenaje a 40 y 45 F con acondicionamiento en comparación con el almacenaje a 50 F sin acondicionamiento.Cuatro semanas de acondicionamiento a 65 F después de almacenaje a 40 y 45 F redujeron los azúcares de reducción a los niveles iniciales que existían al tiempo de la cosecha.

Comparison of Reported Lateral Potato Pressures

ABSTRACT A consistent analysis procedure and corrections for initial fill conditions indicate that Schaper and Yaegers (1982) data best approximate reported maximum pressure conditions. Previous suggested pressure guidelines may under estimate maximum sill reactions in shallow bins.