James F. Thompson

Nondestructive determination of total and soluble solids in fresh prune using near infrared spectroscopy

A nondestructive optical method for determining the total solids content (TSC) and soluble solids content (SSC) of fresh whole prune (Prunus domestica L. ‘French’) was investigated. The method, based upon near infrared spectrophotometric techniques, could predict the TSC (r 2 /0. 98, SEP/0.80% FW) and SSC (r 2 /0. 96, SEP/ 1.02%) of prunes. A low cost (

Optical chlorophyll sensing system for banana ripening

2500 2002 USD) diode array-type spectrophotometer was used in the study. # 2002 Elsevier Science B.V. All rights reserved.

ASSESSMENT OF VIBRATION INJURY TO BARTLETT PEARS

An optical chlorophyll sensing system was developed to detect the chlorophyll content of bananas as the fruit ripens. This system shows a high correlation to other peel colour analysis methods (spectral analysis, tristimulus colorimeter analysis, and visual colour matching). Regression equations were developed to predict the chlorophyll content of banana peels, which is primarily responsible for the change in the colour of the peel. This optical chlorophyll sensing system has the following characteristics: rapid response, simple operation, non-destructive measurement, and low cost. The potential application of this system in automatic monitoring of banana ripening is also discussed.

Effects of drain and harvest dates on rice sensory and physicochemical properties

Laboratory tests revealed that palletized fiberboard boxes of Bartlett pears are most susceptible to bruising damage at vibrational frequencies below 40 Hz (cycles/s), which are common in refrigerated highway trailers. Damage studies indicate that of the four frequency regions observed in-transit (3.5 Hz, 9 Hz, 18.5 Hz, and 25 Hz), Bartlett pears are most severely damaged at 3.5 Hz and 18.5 Hz. Laboratory studies also show that fiberboard boxes of pears amplify vibration at frequencies below 40 Hz such that, for some frequencies, the lid of the top box in a pallet is accelerated three to four times more than the level input to the bottom box.

Impact of Storage of Freshly Harvested Paddy Rice on Milled White Rice Flavor

ABSTRACT Timing of field draining and harvesting of rice with meteorological conditions can allow growers to foster conditions for high head rice yield (HRY). The effects of timing of draining and harvesting on rice sensory and physicochemical properties are not well understood. The objective of this study was to determine the effects of varying drain and harvest dates on the sensory and physicochemical properties of M-202 grown in California under controlled field conditions. Drain date had a significant (P 0.05) differences in texture were measured as a result of these parameters being low. Drain date did not affect the volatile composition or flavor of the rice. Harvest date had no effect (P > 0.05) on amylose content and a sig...

Drying Characteristics and Quality of Rough Rice under Infrared Radiation Heating

ABSTRACT Between harvest and the start of drying, paddy rice may be held for more than 24 hr at moisture contents ranging from 16% to >26%. Microbes found on the freshly harvested rice grow under these conditions and produce a wide variety of volatile compounds that impact the flavor/aroma of the white rice obtained after drying and milling of the paddy rice. The contents of 10 volatile microbial metabolites were compared in white rice obtained from paddy rice harvested at differing moisture contents and immediately dried (0 hr) or held for 48 hr before drying. No increases in volatile microbial metabolite levels were observed in white rice obtained from paddy rice that was stored at 17–21% moisture contents for 48 hr. In white rice from paddy rice stored at ≥24% moisture content, 3-methyl-butanol, 2-methyl-butanol, acetic acid, 2,3- butandiol, and ethyl hexadecanoate increased markedly with time. Also in these samples, as determined by a descriptive panel, sour/silage and alfalfa/grassy/green bean flavor...

DRYING CHARACTERISTICS AND QUALITY OF ROUGH RICE UNDER INFRARED RADIATION HEATING

Infrared (IR) radiation heating could provide a high heating rate and rapid moisture removal for rough rice drying. The objective of this research was to investigate the effect of the drying bed thickness on drying characteristics and quality of rough rice subjected to IR heating. Samples of freshly harvested medium grain rice (M202 variety) with 20.5% and 23.8% (w.b.) moisture contents were used for this study. They were dried with two different radiation intensities (4685 and 5348 W m-2) and exposure times of 15, 30, 40, 60, 90, and 120 s for each drying bed thickness. The three tested drying bed thicknesses were single layer, 5 mm, and 10 mm. After IR drying, the samples were tempered for 4 h followed by natural cooling. The drying rate, moisture removal, and temperature of the rice were determined. The rice temperatures after the IR heating were in the range of 35.9°C to 71.4°C. The heating and drying rates decreased with the increase of bed thickness. Up to 2.2% of moisture was removed during natural cooling after tempering, without additional energy input. IR heating under tested conditions did not have adverse effects on rice sensory and milling quality, including total rice yield, head rice yield, and degree of milling of the dried rice. We concluded that a high heating rate, fast drying, and good rice quality can be achieved by IR heating of rough rice to about 60°C followed by tempering and natural cooling with a tested bed thickness up to 10 mm.

EFFECT OF WEATHER AND RICE MOISTURE AT HARVEST ON MILLING QUALITY OF CALIFORNIA MEDIUM-GRAIN RICE

Infrared (IR) radiation heating could provide high heating rate and rapid moisture removal for rough rice drying. The objective of this research was to investigate the effect of drying bed thickness on drying characteristics and quality of rough rice under IR heating. The samples of freshly harvested medium grain rice (M202 variety) with 20.5 % and 23.8% (wb) moisture contents were used for this study. They were dried with two different radiation intensities, 4685 and 5348 W/m2, for six exposure times, 15, 30, 40, 60, 90 and 120 s, for each drying bed thickness. The tested three drying bed thicknesses were single layer, 5 mm and 10 mm. After IR drying, the samples were tempered for 4 hours followed by slow cooling. The drying rate, moisture removal and temperature of rice during drying were measured and calculated. The rice temperatures after the IR heating were in the range of 35.9 to 71.4 oC. The heating and drying rates decreased with the increase of bed thickness. A significant amount of moisture was removed during slow cooling after tempering, without additional energy input. The quality of milled rice, including total rice yield, head rice yield, and degree of milling of the dried rice was evaluated. It was concluded that a high heating rate, fast drying and good rice quality could be achieved by heating rough rice to about 60 oC followed by tempering and slow cooling with a bed thickness up to 10 mm.

Comparison of Instrumental and Manual Inspection of Clingstone Peaches

California’s medium-grain rice industry experiences a wide range of head rice yield (HRY). Average moisture of a representative paddy rice sample is the commercially used predictor of optimum harvest date to achieve high HRY. A two-year field study demonstrated that average rice moisture alone is not an adequate predictor of HRY. The history of rice moisture caused by varying meteorological conditions was needed to predict rice quality. Under typical calm conditions in California, daytime relative humidity is low and at night humidity increases, exposing rice to dew. During this meteorological pattern, HRY could be predicted by assuming that all kernels that dried below 15% moisture during the day would rehydrate at night and fissure, resulting in lost HRY. Harvest weather is also characterized by occasional episodes of dry north wind, lasting several days. These periods have insufficiently long rehydration periods to completely fissure kernels that dropped below 15% moisture, and actual HRY was much above predicted HRY. HRY dropped significantly during periods of dry north winds; however, rice value (government loan value minus drying costs) did not drop significantly during the windy period because the lower loan value was offset by lower drying costs. After the windy period ended, rice was again subject to nighttime dew and regained moisture, resulting in a large reduction in HRY and value. A combination of the range of individual kernel moisture at harvest and history of rice moisture influenced by weather conditions explained a great deal of the total HRY variation experienced by the California rice industry.

The dependence of open field burning emissions and plume concentrations on meteorology, field conditions and ignition technique

The flesh color and firmness of 13,140 clingstone peaches were measured instrumentally at the cannery receiving stations and compared with the current official subjective inspection methods of the California Department of Food and Agriculture. The instruments evaluated were a nondestructive impact firmness sensor, a traditional destructive penetrometer firmness sensor, and a tristimulus color sensor. Instrumental measurements for flesh color and nondestructive firmness gave good agreement (83% across all cultivars) with the current inspection method in categorizing fruit into both mature or immature, and into firm or soft categories. The study shows that objective instrumental inspection methods hold promise as a replacement for subjective methods presently used in clingstone peach inspection at cannery receiving stations.