Phenolic compounds' stability in reduced-calorie plum spread fortified with freeze-dried plum pomace: Effects of processing techniques and pasteurization

Fortified reduced-calorie plum spreads (∼40°Brix), containing 10 % (w/w) freeze-dried plum pomace (FD-PP), were analyzed for phenolic compounds (spectrophotometrically and chromatographically determined) and antioxidant activity to evaluate the effects of processing and pasteurization during the transition from laboratory (LS-S) to industrial scale (IS-S) spread manufacturing. Additionaly, a control sample at an industrial scale (IS-CS) was prepared to estimate FD-PP's functional contribution. The physicochemical properties of spreads and plum materials used (FD-PP and plum purée, PP), were also investigated. IS-S exhibited increased levels of total phenols, total flavonoids, total anthocyanins, catechin, chlorogenic acid, caffeic acid, rutin, quercetin, cyanidin 3-O-glucoside, and cyanidin 3-O-rutinoside, alongside higher antioxidant activity compared to IS-CS. LS-S retained more phenolics than IS-S, possibly due to the pasteurization step (85 °C, 1 h) introduced in IS-S processing. Although characterised by reduced phenolic and anthocyanins content upon pasteurization, appealing colour of the IS-S spread was retained. Significant correlations (p<0.05) were observed across most individual phenolic compounds and antioxidant activity. Standard score (SS) analysis showed that phenolic retention and antioxidant activity were highest in LS-S (SS=0.754), followed by IS-S (SS=0.490) and IS-CS (SS=0.163). Pasteurization and the use of FD-PP contributed to the microbiologically stable spread after 21 days of storage.