Nachiket Kotwaliwale

X-ray imaging methods for internal quality evaluation of agricultural produce.

A number of non-destructive methods for internal quality evaluation have been studied by different researchers over the past eight decades. X-ray and computed tomography imaging techniques are few of them which are gaining popularity now days in various fields of agriculture and food quality evaluation. These techniques, so far predominantly used in medical applications, have also been explored for internal quality inspection of various agricultural products non-destructively, when quality features are not visible on the surface of the products. Though, safety of operators and time required for tests are of concern, the non-destructive nature of these techniques has great potential for wide applications on agricultural produce. This paper presents insight of X-ray based non-destructive techniques such as X-ray imaging and Computed Tomography (CT). The concepts, properties, equipment and their parameters, systems and applications associated with the use of X-rays and CT for agricultural produce have been elaborated.

Physical and mechanical properties of green banana (Musa paradisiaca) fruit

Abstract The physical and mechanical properties of two varieties of green banana fruit, namely, Dwarf Scavendish and Nendran, were determined. The average pulp and peel moisture content were 264.17% (db) and 666.28% (db), respectively for Dwarf Scavendish and 153.39% (db) and 516.41% (db), respectively for Nendran. At these average moisture contents, the average pulp to peel ratios were 1.39 and 2.32, and peel thickness were 3.65 mm and 2.95 mm, respectively. The maximum diameter of fruit without peel was 23.34 mm and 37.08 mm, and average pulp specific gravity was 0.993 and 1.110, respectively for the two varieties. The maximum effective length and width of the banana pulp resting at its most stable position was observed to be 137.0 mm and 66.5 mm, respectively for Dwarf Scavendish and 194.5 mm and 50.0 mm, respectively for Nendran. The maximum load required to cut a cross-sectional slice of pulp was 22.4 N and 28.2 N for the two varieties, respectively. Maximum energy of 686.81 J/m 2 for Dwarf Scavendish and 724.46 J/m 2 for Nendran was required to cut a slice of the fruit. The banana kept in a convex position required the most energy to cut, whereas the plain position was observed to be the best position vis-a-vis the energy requirement and consumer preference of chip shape.

PHYSICAL CHARACTERISTICS OF PECAN COMPONENTS: EFFECT OF CULTIVAR AND RELATIVE HUMIDITY

Physical characteristics of pecan nuts describing size, specific gravity, shell thickness, and nutmeat-to-shell ratio are not only quality indicators but are also important for the design of handling and processing equipment for pecans. Length, maximum and minimum diameters, and shell thickness were measured for 30 samples of ‘Native-A’, ‘Native-B’, ‘Squirrels Delight’, and ‘Maramek’ cultivars equilibrated at 40% and 78% RH. Length of whole pecan nuts varied from 29.3 to 45.2 mm, whereas maximum and minimum diameters around the largest periphery varied from 23.9 to 16.3 and from 21.1 to 10.0 mm, respectively. Specific gravity of pecan nuts, shell, and nutmeat was determined by a water displacement method using a pycnometer bottle. Mean specific gravities were observed to be 0.837 for whole pecan nut, 1.065 for pecan shell, and 0.945 for pecan nutmeat. In general, nutmeat-to-shell ratio was greater than 1.

Radiography, CT and MRI

Quality control is an important aspect of food production and processing providing foods of acceptable nutritional value, and safety of products. Several characteristics such as size, shape, density, maturity, moisture content, oil content, flavor, firmness, tenderness, color, defects, blemishes, etc., are routinely used in the quality control of agricultural and biological food products. Until recently, most analytical techniques used in quality control required isolation of the food component of interest. The original properties of the product are, therefore, destroyed during sample preparation and analysis. Oftentimes, such analyses are expensive, time consuming, and require sophisticated instrumentation, and hence are not suited for “on-line” quality control of food products. Recent progress in the development of instrumentation utilizing the some physical, optical, acoustic and electromagnetic properties of food products has provided several nondestructive techniques for quality evaluation. Many such methods are highly sensitive, rapid, and reproducible, and have been successively used in routine “on-line” quality control of a large number of samples.

Calibration of a Soft X-Ray Digital Imaging System for Biological Materials

Soft X-ray imaging of agricultural products for quality determination is gaining worldwide interest. Recent advances in technology have made it possible to capture, store, and instantaneously process digital X-ray images at higher resolution for lower cost. An X-ray imaging system was developed and calibrated to capture images with a resolution of 1024 × 1024 pixels over a 50 × 50 mm area. Maximum X-ray tube voltage was 50 kVp, maximum current was 1 mA, and signal integration time ranged from 460 to 6700 ms. The system consists of an X-ray source tube, a camera composed of a CMOS photodiode array, a frame grabber, and a data acquisition and control card. Because the X-ray beam is polychromatic, and the detector responses are variable, calibration is necessary to relate image intensity to X-ray attenuation. Imprecision of the system was 0.64% of the response range (1.63 gray level for an 8-bit pixel depth). Response, measured as mean pixel intensity, varied linearly with X-ray tube current and integration time and had a quadratic relationship with peak tube voltage. A regression model was developed to estimate blank image intensity at higher voltages and currents. Prediction and validation errors for the model were 0.46% and 1.06% (1.18 and 2.72 gray level), respectively. Beam hardening effect was demonstrated using a polystyrene target. The procedure explained in this article can be used to calibrate a soft X-ray imaging system for radiometric measurements.

DIGITAL RADIOGRAPHY FOR QUALITY DETERMINATION OF SMALL AGRICULTURAL PRODUCTS: DEVELOPMENT AND CALIBRATION OF EQUIPMENT

Soft X-ray imaging of agricultural products for quality determination is gaining worldwide interest. Recent advances in technology have made it possible to capture and store or instantaneously process digital X-ray images at higher resolution for lower cost. An X-ray imaging system was developed and calibrated to capture images with a resolution of 1024 x 1024 pixels in 50 mm x 50 mm area. Maximum X-ray tube voltage was 50 kVp, maximum current 1 mA, and signal integration time ranged from 460 to 6700 ms. The system consist of an X-ray source tube producing polychromatic X-rays, a camera composed of CMOS photodiode arrays, a frame grabber, and a data acquisition and control card. Because the X-ray beam is polychromatic, and the detector responses are variable, calibration is necessary to relate image intensity to X-ray intensity. Imprecision of the system was 1.62 gray level for 8-bit pixel depth. Response, measured as mean pixel intensity, varied linearly with X-ray tube current and integration time and had a quadratic relationship with peak tube voltage. A statistical model was developed to estimate blank image intensity at higher voltages and currents. Prediction and validation errors for the model were 1.18 and 2.72 gray level, respectively. The Beam hardening effect was demonstrated using polystyrene.

Quality characteristics of sauerkraut fermented by using a Lactobacillus paracasei starter culture grown in tofu whey

The quality parameters of sauerkraut fermented using Lactobacillus paracasei in terms of its lactic acid bacteria count, texture, colour and biochemical properties were studied. As a starter culture L. paracasei grown in tofu whey was used for sauerkraut fermentation. The experiments were planned using central composite rotatable design of response surface methodology for input variables – culture volume (ml), fermentation time (days) and salt concentration (g/100 g). The linear and interactive effect of variables on responses was understood by statistically significant (p < 0.01) second-order models. Amongst all the input variables culture volume was found to have an overwhelming effect over all the responses. There was a significant (p < 0.01) increase in the lactic acid bacteria count of finished product; it was less hard but there was a departure in colour from the traditional product. The optimized condition for sauerkraut fermentation in terms of culture volume (ml), fermentation time (day) and salt concentration (g/100 g) was 30 ml, 28 days and 1 g/100 g, respectively. It was also observed that phenolics content was better in starter culture sauerkraut over the one traditionally prepared.