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Öğe Effects of different factors on sensory attributes, overall acceptance and preference of Rooibos (Aspalathus linearis) tea(Wiley, 2005) Dos, A; Ayhan, Z; Sumnu, GEffects of serving size, gender, age, tea type, tea-making technique and water quality on the sensory attributes (appearance, aroma and taste), overall acceptability and preference of Rooibos tea were investigated. In general, there were significant effects of age and main factor interactions on the attributes and product acceptability (P <= 0.05). The interaction of serving size, gender and age affected the acceptability of Rooibos (P <= 0.05). Although there was significant difference between natural and vanilla-flavored tea in terms of color, clarity, odor and taste (P <= 0.05), no difference was observed in the product acceptability (P > 0.05). The tea-making technique only affected the odor with traditionally brewed tea having lower intensity scores than the infused tea. The tea prepared using natural spring water was found to be clearer and had higher acceptability, scores than the tea prepared using tap water (P > 0.05). There was no existing significant preference for the natural Rooibos over the vanilla-flavored one, and the traditionally brewed tea over the infused one; however the tea prepared using the spring water was preferred over the one prepared using tap water.Öğe Evaluation of heat seal quality of aseptic food containers by ultrasonic and optical microscopic imaging(Springer-Verlag, 2003) Ayhan, Z; Zhang, QHNon-destructive testing by the ultrasonic imaging method was evaluated to determine the heat seal quality of aseptically produced semi rigid cups, sealed at temperatures ranging from 150 to 200 degreesC. Non-contact ultrasonic testing in pulse/echo mode using high frequency sound waves generated by a 20 MHz ultrasonic transducer was used to evaluate heat-seal quality. In order to relate ultrasonic response with the actual seal condition, various seal regions of a semi rigid container were sectioned for optical microscopic imaging and seal characterization. Results showed that ultrasonic signals could reflect the effects of the sealing process on the seal integrity. Change in the ultrasonic signals indicated an insufficient or non-uniform heat seal at sealing temperatures of 150-170 degreesC, resulting in weak seals or discontinuities. Short seal width was observed at all sealing temperatures, indicating unparallel alignment of the sealing tool. Optical imaging correlated well with ultrasonic imaging. However, uniformity of heat seal did not correlate well with the magnitude of the ultrasonic signal, possibly due to non-uniform surfaces of heat seals. These results suggest that this non-destructive ultrasonic inspection system detects the quality of heat seals, which can eliminate potential failures and improve process control.Öğe Flavor, color, and vitamin C retention of pulsed electric field processed orange juice in different packaging materials(Amer Chemical Soc, 2001) Ayhan, Z; Yeom, HW; Zhang, QH; Min, DBEffects of packaging materials, storage temperature, and time on the stability of pulsed electric field (PEF) processed orange juice were investigated. Single-strength orange juice was treated with PEF at an electric field strength of 35 kV/cm for 59 mus using an integrated pilot plant scale PEF processing and glovebox packaging system. The retention of eight orange juice aroma compounds, color, and vitamin C in glass, polyethylene terephthalate (PET), high-density polyethylene, and low-density polyethylene were evaluated at 4 and 22 degreesC for 112 days; Packaging material had a significant effect (p less than or equal to 0.05) on the retention of orange juice aroma compounds, color, and vitamin C. PEF-treated orange juice had a shelf life of >16 weeks in glass and PET at 4 degreesC.Öğe Inspection of seal integrity of food packages using ultrasound and pressure differential techniques(Amer Soc Agricultural & Biological Engineers, 2001) Ayhan, Z; Zhang, QH; Farahbakhsh, B; Kneller, MFood packages undergo incubation and inspection to ensure that packages are sealed tight and protect the food from contamination and spoilage. Over the years many inspection techniques are used with varying degrees of success. With this study, two techniques, ultrasound and pressure differential technique, were assessed and the effectiveness of these techniques was quantified. Non-contact, immersion type ultrasonic testing in pulse/echo mode using high frequency sound waves was evaluated for use in defect detection in the seal area of semi-rigid cups and polymeric trays. At disparities within the seal, sound waves generated by 20-MHz ultrasonic transducer were reflected back to the receiver. Received ultrasonic signals, or echoes, were used to develop A-scan and C-scan presentations. Discontinuities in the seal, short seal, non-bonded areas, imbedded foreign matter such as wire and Teflon in the seal, contaminated seal, and abrasion were detected using ultrasound based on reduced signal strengths. Integrity of meals-ready-to-eat (MRE) pouches was inspected using a new pressure (vacuum) differential technique. This technique is based on a three-step approach. To evaluate the system, air was linked into a test chamber through a calibrated needle valve simulating a leak at different leak rates. A simulated leak that generated values higher than reference, and dependant upon the leak rate, was accepted or rejected by the leak tester The technique proved to be effective, although, short-sealed non-vacuum packed pound cake pouches failed during subsequent leak testing.Öğe Seal bond characterization of laminated plastic food cups by scanning electron and optic microscopes(John Wiley & Sons Ltd, 2004) Ayhan, ZHeat seals of laminated semi-rigid food cups were evaluated to characterize the seal bond. Laminated lidding material was sealed at temperatures of 160-180degreesC to thermoformed cups. Various seal regions of the cups with different ultrasonic signal strengths (%) were sectioned at the rim and examined using optical and scanning electron microscopes (SEM). Ultrasonic signals were able to pinpoint seal defects; however, the magnitude of the signals did not relate to the actual seal condition or seal quality affected by the sealing process. This was attributed to the very short seal width and non-parallel surface of the heat seal, which possibly resulted in signal loss by reflection and scattering from the seal surface. C-scan of ultrasound, SEM and optical microscopic images provided the information that the heat-sealing process was unstable, due to insufficient and non-uniform heat-seal temperature or pressure, misalignment of the sealing jaws or non-parallel sealing or cutting unit configuration. Copyright (C) 2004 John Wiley Sons, Ltd.
