Procedures for Moisture Analytical Tests Used in Cotton Ginning Research

Abstract

Abstract. Cotton post-harvest processing research requires moisture content determination for seed cotton, cottonseed, and lint. Methods for determining moisture content have changed and are no longer consistent between laboratories. This research compared standard procedures documented in 1972 and those currently practiced for finding moisture content by oven drying, and quantified the variability. Seed cotton from four modern cultivars (ranging from 9.4% to 36.8% foreign matter), lint, and cottonseed were brought from dry conditions, blended, and then stored for more than 30 days in a controlled environment (21°C, 65% RH) to reach uniform moisture content. Additionally, 150 seed cotton samples were placed in plastic zipper bags and sent by air freight to a distant location and back or stored on-site. Drying baskets (652 cm3) were loaded, in random order, with 25, 35, 50, 71, and 100 g seed cotton or 10, 14, 20, 28, and 40 g lint. Cottonseed was placed in 45 cm3 aluminum cups (10 g) or 800 cm3 aluminum baskets (50 g). Wet weights were determined in the controlled environment. After drying, replicated sets of seed cotton, lint, and cottonseed samples were weighed inside a drying oven and then outside the oven while still hot. Some samples were dried for twice the recommended duration. Sample location in the ovens was tracked. Weighing hot seed cotton samples outside the oven after drying increased apparent moisture content by approximately 0.5% due to air buoyancy; weighing lint samples outside the oven increased apparent moisture content by 1%. Smaller differences in apparent seed cotton moisture content were found when halving or doubling the amount of material in drying baskets or doubling the drying duration. Foreign matter had a minor influence on apparent moisture content. Storage for three days and shipping by air freight in plastic zipper bags did not measurably change the apparent moisture content of seed cotton. Sample location within the drying oven made no difference. Current practices are satisfactory if dry weight location is taken into consideration. Measurement uncertainty has decreased compared to 50 years ago, but the recommended minimum number of samples per treatment was increased slightly for greater statistical power. Keywords: Cotton lint, Cottonseed, Moisture content, Oven drying, Seed cotton.

COTTON GINNERS HANDBOOK: Moisture Measurement

“…This approximation method is easier because it does not require expensive ovens, is more convenient, and for most cases, the bias is consistent and within 0.5% MC ,which is sufficient for gin operations. The reference for weighing hot outside the oven is provided in Funk et al (2018). Byler's (2004a) test reported that seven, 1-g samples were found to result in the same confidence in MC values as three, 20-g specimens, while consuming 12% as much cotton.…”

Effects of harvesting and ginning practices on Southern High Plains cotton: fiber quality

“…Two seed cotton sub-samples per gin lot (500 g each) were collected from the wagon before seed cotton cleaning and at the feeder prior to ginning for fractionation and gravimetric moisture content analysis using the method described by Funk et al. 33 Two lint sub-samples per gin lot (500 g each) were collected before and after the lint cleaner used in each ginning system for high volume instrument (HVI) and Advanced Fiber Information System (AFIS) fiber analysis. Since the lint cleaning systems used with the HSRG and saw ginning systems were different, fiber analysis before and after lint cleaning was conducted to highlight differences in the ginning systems alone (i.e.…”

“…Lint was valued based on the results of HVI analysis and all years were standardized to the 2012 Commodity Credit Corporation Loan Chart. 36 Gravimetric moisture content 33 was also measured on the lint sub-samples collected after lint cleaning. All seed cotton fractionation was conducted by USDA ARS personnel at the Cotton Production and Processing Research Unit in Lubbock, Texas, while all gravimetric moisture content analyses were conducted by USDA ARS personnel at the Southwestern Cotton Ginning Research Unit in Mesilla Park, New Mexico.…”

Saw Thickness Impact on Cotton Gin Energy Consumption

“…Seed cotton samples (150 g each) collected from the overflow hopper were placed in plastic bags for foreign matter analysis by fractionation (Shepherd, 1972). Additional seed cotton samples (50 g each) were also collected from the overflow hopper and placed in air-tight containers for moisture content determination by oven method (Funk et al, 2018).…”