## 4 Impacts of HTST and UHT on Food Quality
### Sensory Quality  
Highly significant is the impact of preservation methods on sensory qualities. The high temperatures lead to changes in the contents of various ingredients, transformations of substances and occurrences of chemical processes that change the taste, smell and color of products.  
[PERSON] et al. [25] evaluated the quality of selenium-enriched kiwi juice treated at 110 \({}^{\circ}\)C for 8.6 s. They showed that clear and cloudy preserved juices received significantly lower scores for color and appearance, flavor and overall acceptability compared to their raw counterparts. Only for taste was there no significant difference among trained panelists. In addition, in all distinguishing factors, thermally preserved juices were rated worse than HPP-treated juices. [PERSON] et al. [39] came to different conclusions; the UHT-preserved papaya beverage did not differ in color and appearance, while it had worse mouth feel, flavor and overall acceptability compared to raw juice. In contrast, raw clear cucumber juice did not differ in color and appearance from the UHT sample [41]. When stored, cucumber juices received lower scores after 20 days than immediately after preservation. [PERSON] et al. [41] and [PERSON] et al. [25] showed that thermally preserved juices scored lower than HPP juices in all distinguishing factors.  
[PERSON] et al. [64] conducted sensory evaluations of lemonade, citrus juice and green juice. The HTST-preserved lemonade scored better in flavor and overall liking than the raw sample, and the preserved green juice scored worse in overall liking and more than 30% worse in color than raw juice. In contrast, the preserved citrus juice was not significantly different from its untreated version. The researchers also sensory evaluated those products preserved by other methods--mostly, the HPP method and UV-C light changed the ratings to a lesser extent compared to HTST. [PERSON] et al. [46] found that juice subjected to HTST preservation showed less acceptable odor and taste than samples subjected to PEF preservation. [PERSON] et al. [50] compared orange juice preserved at 94 \({}^{\circ}\)C/26 s and a sample preserved with a combined thermosonification/PEF method. The panelists found no significant differences between these samples in terms of color, odor, sweetness, acidity, flavor and acceptability. However, the HTST-preserved juice was rated as being blander than the TS/PEF juice by twice as many evaluators. [PERSON] et al. [16] found that an increase in the processing temperature for the same product can result in poorer flavor scores among evaluators. The HTST-preserved orange juice was rated worse overall and in terms of flavor and aroma than fresh juice; however, even lower scores were given to the UHT-preserved sample [22]. [PERSON] et al. [106], based on sensory evaluations, determined the shelf-life of orange juice, which they indicated as being 60 days at 0 \({}^{\circ}\)C and 47 days at 5 \({}^{\circ}\)C. This is about one-third to one-half shorter times than when HPP treatment was used, indicating a lower level of preservation of the product's relevant sensory attributes.