Introduction
Due to the strong competition among industries today, many business organizations and producers focus and come up with strategies and innovations, which would improve and develop their products. Such products include food and dairy products, and chocolate among others. The high demand of consumers for chocolate and other sweet products enable manufacturers and producers to come up with innovative ways on improving quality control and the character of chocolates. With this, this paper discusses a specific technique in improving the characterization of chocolate, which would be useful in enhancing its quality control.
Technique Chosen: Terahertz Time Domain Spectroscopy
Jorden, Rutz and Koch (2006) reports that quality inspection gains more and more importance in food industry, particularly in chocolate production, and with this process, contamination from different sources are being detected using metal detectors. However, the use of metal detectors is not very efficient, for its spatial resolution is not very high. Because of this, many chocolate products are being wasted, rejected and discarded, as only a number are contaminated and some are not. With this problem, it was pointed out that the goal of lowering the high rejection rates could be accomplished in using a higher spatial resolution, which could even detect non-metallic contaminations, such as stones that come from natural products, or glass particles (Jorden, Rutz and Koch 2006).
With this problem at hand, many industries expressed the belief of using terahertz or THz waves, which may be used in collaboration with other techniques to determine chocolate contamination. Terahertz or THz waves, specifically, the process of terahertz time domain spectroscopy can be used because it can obtain images of samples, which are opaque in the visible and near-infrared regions of the spectrum (‘Terahertz Radiation’ 2006). This process can be used to identify chocolate contamination because chocolate is has high absorbance and thick, which would make THz radiation applicable (‘Terahertz Radiation’ 2006). In addition, because the consistency and physical characteristics of chocolate, such as its color and viscosity, would make contamination invisible, THz time domain spectroscopy would be a possible solution for detection, with the use of the radiation it emits. In this way, the quality control of such products will be improved, to further meet the demands and expectations of its consumers.
Basis for Chosen Technique, Advantages and Disadvantages
Due the presence of contamination in the chocolate products, detection must be improved to ensure the high standard quality of the chocolates. In addition, because of the inefficiency and waste brought about by the use of the present detection methods, the use of terahertz radiation for the Terahertz time-domain spectroscopy or THz TDS was applied. Jorden, Rutz and Koch (2006) reports that Terahertz time-domain spectroscopy is an original technique in the field of non-destructive and contact less testing, wherein short electromagnetic pulses with a frequency content between 50 GHz and 2.5 THz are employed to characterize different sample materials. In addition, an optoelectronic approach is used to generate THz radiation, wherein short optical pulses from a femtosecond laser excite photoconductive dipole antennas, and on the emitter side a short current pulse is generated, which radiates according to Maxwell’s equations of an electromagnetic wave, producing the THz pulse. The THz waveform is scanned by delaying the two laser pulses in the emitter and detector arm with respect to each other, and every position of the delay line provides a certain time delay that gives one single point of the THz waveform, which would enable THz pulses to be obtained. Moreover, contamination of the chocolate samples can be measured using the THz images, which contains time-domain data including the temporal shift of the pulse maximum or frequency-domain data such as the integrated intensity in a certain frequency interval, and in this way, THz imaging measurement yields many images with different information. Using THz pulses, contamination can be detected, for the graph or pulses can show the differences between the composition of the chocolate samples (Jorden, Rutz and Koch 2006).
This process or technique is beneficial or advantageous because primarily, THz radiation is not ionizing due to its low photon energy and is therefore completely harmless (Jorden, Rutz and Koch 2006). Unlike other X-rays, THz radiation is safe for biological tissues, and images formed with it can have relatively good resolution, being less than 1 millimeter (‘Terahertz Radiation’ 2006). This means the use of this kind of radiation poses no threat or effect on the chocolate products, therefore, will not affect human consumption. It also suggests that the images formed using the process will be essential in quality control, manufacturing, packaging and process monitoring. Secondly, chocolate bars are relatively transparent for THz radiation, since they contain mostly fat with only a very low content of water, and contaminations including small stones, screws or glass splinters act as scattering objects in terms of the wavelength and change the shape of the measured pulse (Jorden, Rutz and Koch 2006). As mentioned, due to the color, viscosity and opaqueness of chocolate, it would be difficult to detect contaminations easily, so with the use of the process, detection would be possible without contact. In line with this is the last advantage, wherein due to the pulsed nature of the radiation, one can draw comparisons to ultrasound, for compared to conventional metal-detectors and ultrasound techniques, terahertz time-domain spectroscopy is able to sense non-metallic items without contact (Jorden, Rutz and Koch 2006).
However, despite its advantages are the disadvantages or limitations, which may largely affect the result of the process. First, the process depends on the alignment and positioning of the emitters and detector arms, so slight misalignment will significantly shift the relative phase of the electric field components (Castro-Camus et al. 2005). Another disadvantage is that the collection of data depends on time, so without proper timing, the efficiency of detection might be lessened. With these limitations, the use of the process should be carefully evaluated to ensure the gathering of reliable results.
Other Techniques Used
Another useful technique capable of characterization of chocolate is Differential Scanning Calorimetry or DSC, which is a complex program with multiple heating, cooling and isothermal steps that can be easily constructed and utilized to simulate real-life processing conditions (Robinson and Sichina 2000). The power compensated DSC gives a number of advantages in chocolate analysis, as the design of the sample and reference low mass furnaces yields very close control over the sample environment, which allows the DSC to produce specific and accurate thermal treatments for reliable material comparison or to investigate effects of changes in processing conditions. In addition, its sensitivity to small changes makes it an ideal tool to identify sample characteristics or processing changes (Robinson and Sichina 2000). With Differential Scanning Calorimetry, detection of unnecessary objects in the products can be obtained, for the melting point of chocolate is lower than solid contaminations.
Another characterization technique used is Size Exclusion Chromatography, which is a well-established characterization technique for products with high viscosity even at low concentration, such as chocolate. Through this technique, along with low angle light scattering, refractive index and viscometer detectors, several aspects can be measured, including molecular weight distribution, viscosity, molecular size, molecular architecture and cumulative weight fraction (Marheineke 2007). Using Size Exclusion Chromatography, contamination will be detected, as each particle present will be known, and if ever, unnecessary particles will be present, the molecular weight, viscosity, and concentration of the product will be altered. The alteration of the chocolate sample will be the indicator of the presence of contaminations in the products.
Performance of Technique based on the Micro Structure of Product
Results of the technique show that metal, stone, or glass contaminations can be detected in chocolate bars with a spatial resolution of less than 1 millimeter, where the transmitted intensity for glass and stone contaminations is lower due to higher absorption and scattering losses. Metal, on the other hand, reflects all THz radiation, which decreases the transmitted intensity, and even if the chocolate is measured in its own original plastic package, the contamination is clearly visible. Plastic foil is nearly transparent to THz radiation, while aluminum foil reflects all THz radiation and thus cannot be investigated using the process (Jorden, Rutz and Koch 2006). Through the process, manufacturers will be able to examine and improve quality control of their products, given the speed and efficiency in producing the data and the scanning of the products. This process would help many chocolate manufacturers in detecting solid contaminations and reducing wastes. This would also improve the quality of products, as each chocolate bars or samples will have consistency in terms of content, weight and quality.
Moreover, results of the data show that if there are any contaminations inside the chocolate bar, like a stone or a glass splinter on the scale of millimeters, the THz pulses produce a different shape, where two smaller pulses appear close to each other, which are generated by two portions of the main THz pulse. One part of the pulse travels aside the contamination, and the second part travels through the contamination, which experiences a time delay due to the higher refractive index of the glass splinter or the small stone. Since the first THz pulse is smaller than the main one, a dip occurs in the sum of two line scans indicating the contamination (Jorden, Rutz and Koch 2006). Based on the results of the pulse, contamination will be detected effectively and efficiently because as the products pass through the detectors, quality control personnel will be able to detect the presence of unnecessary items in the products using the reading of the pulse. In this way, wastes will be lessened and quality of the products will be improved simultaneously.
Conclusion
The use of the Terahertz time-domain spectroscopy is one helpful technique in determining the contaminants in chocolate products. The use of this technique must be developed further to help lessen wastage and improve the quality control of chocolate manufacturing companies. In this way, they can meet the standards and focus on the satisfaction and loyalty of their customers.
References
Castro-Camus, E, Lloyd-Hughes, J, Johnston, M, Fraser, M, Tan, H, and Jagadish, C 2005, Polarization-Sensitive Terahertz Detection by Multicontact Photoconductive Receivers, Applied Physics Letters, vol. 86, no. 254102.
Jordens, C, Rutz, F and Koch, M 2006, Quality Assurance of Chocolate Products with Terahertz Imaging, Institute of Hochfrequenztechnik, Germany.
Marheineke, N 2007, Determination of Molecular Weight and Structural Distribution of Carrageenan Samples by Aqueous GPC, Laboratory Equipment, viewed 9 January 2007, <http://www.laboratoryequipment.com/ShowPR.aspx?PUBCODE=020&ACCT=2000012535&ISSUE=0505&RELTYPE=PR&ORIGRELTYPE=ACHF&PRODCODE=00004141&PRODLETT=D&CommonCount=0>.
Robinson, P and Sichina, B 2000, Characterization of Chocolate Using Power Compensated Differential Scanning Calorimetry, Thermal Analysis.
Terahertz Radiation 2006, Wikipedia the Free Encyclopedia, viewed 9 January 2007, <http://en.wikipedia.org/wiki/Terahertz_radiation>.
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