Tímea Kaszab

Methods for Improving Image Quality and Reducing Data Load of NIR Hyperspectral Images

Near Infrared Hyperspectral Imaging (NIRHSI) is an emerging technology platform that integrates conventional imaging and spectroscopy to attain both spatial and spectral information from an object. Two important problems in NIRHSI are those of data load and unserviceable pixels in the NIR sensor. Hyperspectral imaging experiments generate large amounts of data (typically > 50 MB per image), which tend to overwhelm the memory capacity of conventional computer systems. This inhibits the utilisation of NIRHSI for routine online industrial application. In general, approximately 1% of pixels in NIR detectors are unserviceable or ‘dead’, containing no useful information. While this percentage of pixels is insignificant for single wavelength imaging, the problem is amplified in NIRHSI, where > 100 wavelength images are typically acquired. This paper describes an approach for reducing the data load of hyperspectral experiments by using sample-specific vector-to-scalar operators for real time feature extraction and a systematic procedure for compensating for ‘dead’ pixels in the NIR sensor. The feasibility of this approach was tested for prediction of moisture content in carrot tissue.

No Major Differences Found between the Effects of Microwave-Based and Conventional Heat Treatment Methods on Two Different Liquid Foods

Extension of shelf life and preservation of products are both very important for the food industry. However, just as with other processes, speed and higher manufacturing performance are also beneficial. Although microwave heating is utilized in a number of industrial processes, there are many unanswered questions about its effects on foods. Here we analyze whether the effects of microwave heating with continuous flow are equivalent to those of traditional heat transfer methods. In our study, the effects of heating of liquid foods by conventional and continuous flow microwave heating were studied. Among other properties, we compared the stability of the liquid foods between the two heat treatments. Our goal was to determine whether the continuous flow microwave heating and the conventional heating methods have the same effects on the liquid foods, and, therefore, whether microwave heat treatment can effectively replace conventional heat treatments. We have compared the colour, separation phenomena of the samples treated by different methods. For milk, we also monitored the total viable cell count, for orange juice, vitamin C contents in addition to the taste of the product by sensory analysis. The majority of the results indicate that the circulating coil microwave method used here is equivalent to the conventional heating method based on thermal conduction and convection. However, some results in the analysis of the milk samples show clear differences between heat transfer methods. According to our results, the colour parameters (lightness, red-green and blue-yellow values) of the microwave treated samples differed not only from the untreated control, but also from the traditional heat treated samples. The differences are visually undetectable, however, they become evident through analytical measurement with spectrophotometer. This finding suggests that besides thermal effects, microwave-based food treatment can alter product properties in other ways as well.

Method to Assess Changes in Carrot Ingredients

Abstract The objective of the work was to determine mechanical characteristics and taste attributes of carrots during different storage conditions. Purpose was to determine acoustic and impact stiffness coefficients and cutting force for the tested carrots for different storage conditions.

Prediction of Carrot Quality Characteristic from Spectral Properties

The objective of the work reported here was to determine carrot quality characteristics from the NIR spectrum and from other parameters for different moisture contents. The change in the moisture content caused a definite change in the firmness, actually in the specific cutting force for the two cultivars. This result shows that carrot firmness is very sensitive to the moisture content. Therefore, firmness can be a very good characteristic for predicting carrot moisture content during storage. The relative absorbance turned out to be a good characteristic of the carrot moisture content in the1450±10nm wavelength interval. However, the relative absorbance is not very sensitive to the moisture content. The color characteristics - a*, b* and C values – did not show a definite change in the function of the moisture content. However, these color characteristics are suitable for distinguishing carrot cultivars and the xylem and phloem tissue parts of the carrot.

Water Content Variations in Carrot Tissue by Hyperspectral Imaging

The objective of the work reported here was to analyze the variations in the water content of carrot during the storage by hyperspectral imaging and to determine relationship between spectral characteristic and water content reduction. Relative absorption spectrum was recorded on the tissues in the wavelength range from 900 to 1750 nm. The results show that the reduction in the water content of carrot provides with a definite increase in the absorption signal level measured by hyperspectral imaging in the range below 1400 nm wavelength. Relationship was found between the spectral parameter and storage time. Consequently, hyperspectral imaging is suitable for prediction of water content of carrots on the basis of the relationship between the spectral parameter and relative mass reduction.

Method for the Measurement of Viscoplastic Materials

The objective of the work was to determine firmness of different cottage cheese types. Therefore, the task was to develop rapid measurement method for testing viscoplastic materials, to determine texture characteristics of cottage cheese and similar milk products. The instruments used are as follows: precision penetrometer and special purpose torque meter. The latter one applies a new method, because the conventional viscometers are not suitable for the measurement of cottage cheese.