Cancer-Related Constituents of Strawberry Jam as Compared with Fresh Fruit

The health awareness recently shown by consumers has led to a demand for health beneficial products. In particular, researchers are currently focusing their studies on the search for foods for cancer prevention activity. In the present work, we study comparatively the effect of two different processing methods on the contents of phenolic compounds (i.e., ellagic acid, myricetin, quercetin and kaempferol) with antioxidant and antitumor properties in strawberry jams. In turn, the results obtained were compared with those of unprocessed fruit. Additionally carcinogenic heat-induced compounds formed by the two jam making methods were evaluated. Decreases of total ellagic acid from 138.4 µg/g to 86.5 µg/g were measured in jam as compared with the intact fruit. Even higher losses of up to 90% of total flavonols were found in strawberry after the jam-making process. A comparison between the two processing methods proved shorter heating periods (around 60 min) even at temperatures as high as 100 °C enabled losses of antioxidant phenolics to be minimized. Carcinogenic heat-induced volatile compounds, mainly Maillard reaction products, were formed as a result of thermal treatment during jam processing. However, shorter heating periods also helped reduce the formation of these harmful compounds. These results are deeply discussed. From a practical standpoint, the processing conditions here proposed can be used by industry to obtain strawberry jam with higher content of antioxidant flavonoids and, at the same time, reduced amounts of carcinogenic compounds.