Eureka! Institutional Repository

Peach (Prunus persica) is the third most produced temperate fruit tree after apple and pear, it originates from China and is widely consumed as fresh fruit, juice and as compote. All parts of the peach contain high levels of phytochemicals with biological activities that could be used in various applications in food, pharmaceuticals and cosmetics. Therefore, the utilization of the by-products, peels and pits, of the peach processing industry is of particular interest. Peach pits account for 6-7% of the total weight of the fruit and constitute the majority (70-80%) of solid waste from canneries and peach juice industries. In this Master Thesis, the phenolic content of peach seeds was studied using two extraction methods, the ultrasound assisted extraction and the conventional extraction with stirring. Furthermore, the effect of various extraction parameters on the total phenolics obtained in the extract was examined and the two extraction methods used were compared in terms of their performance and parameter values. The parameters examined for the ultrasonic assisted extraction were temperature, extraction time, pulse intensity and pulse duration/pulse interval ratio. In the case of the conventional extraction method the factors investigated were temperature and the duration of the extraction. Initially, water was chosen as the extraction medium, the choice of which was based on literature data, as in many studies it is presented as a particularly effective solvent for phenolic components, but also because the aim of this essay is to evaluate an economic, easy and environmentally friendly extraction process. For the same reasons, a solvent:seed ratio of 20:1 ml/g was used. The temperatures at which the extractions were carried out for both methods were 20, 30 and 40 °C while the extraction times were 2.5 and 10 min for the U.A.E and 30, 60 and 120 min for the conventional extraction. In the case of U.A.E, pulse intensity was applied at two levels of 40 and 80% and the pulse duration/pulse interval ratio was set at 3 levels 1/1, 2/1 and 3/1. The maximum extraction yield was found to be 16.86 mg GAE/g of dry peach seeds and was recorded when the extraction method that was applied, was ultrasound assisted extraction, with treatment conditions: temperature 30 °C, treatment time 10 min, pulse duration/pulse interval 2 /1 and pulse intensity 40%. Significantly lower was found to be the optimum yieldof the conventional extraction with stirring, 6.77 mg GAE/g of dry peach seeds, which was recorded with extraction conditions: temperature 30 °C, treatment time 60 min.