Blueberry pulp quality upon pretreatment, freezing and storing

Abstract

Cilj rada bio je istražiti utjecaj načina pripreme i zamrzavanja te skladištenja na parametre kvalitete, senzorska svojstva, ukupne fenole i antioksidacijski kapacitet pirea borovnice. Pire svježe borovnice sorte Jersey prije zamrzavanja bio je predtretiran blanširanjem i ultrazvukom visokog intenziteta (UZ), te je kao kontrolni uzorak služio pire bez predtretmana. Zamrzavanje na temperaturu -18 oC provedeno je uz izlaganje visokim tlakom, te konvencionalno u komori (kontrola). Zamrznuti pirei skladišteni su tijekom četiri mjeseca, također, na temperaturi -18 oC. Analize su provedene prije i nakon 4 mjeseca skladištenja. Tijekom skladištenja najmanje promjene topljive suhe tvari, pH, ukupne kiselosti i boje određene su u netreretirani pireu zamrznutom u komori. U svim uzorcima došlo je do povećanja antioksidacijskog kapaciteta i višestrukog povećanja udjela ukupnih fenola. Bolje očuvana senzorska svojstva određena su u pireima zamrznutim u komori i to okus u blanširanom pireu, a izgled u onom tretiranom UZ.The aim of this study was to investigate the influence of different way of pre-treatment and freezing, as well as storing at -18oC on the quality parameters, sensory attributes, total phenols and antioxidant capacity of blueberry pureés. Pureé of fresh blueberry (var. Jersey) before freezing was treated by blanching and high intensity ultrasound (US), and as a control sample was pureé without pre-treatment. Freezing at -18 °C was conducted with exposure to high pressure, and in the chamber (conventional way as control). Frozen pureés were stored for four months, also at temperature - 18 °C. Analyses were performed before and after 4 months. During storage the least changes of soluble solids, pH, total acidity and color were determined in untreated pureé frozen in the chamber. In all samples, there was a higher antioxidant capacity and multiple increase of total phenols. Sensory attributes of pureés frozen in the chamber and stored 4 months were better scored especially the taste of the blanched pureé, and the appearance of the ultrasound treated pureé