Health-promoting compounds changes of a green fresh vegetables smoothie during shelf life

Abstract

A green fresh vegetables smoothie rich in health-promoting compounds was developed. Two thermal treatments to reduce microbial load and preserve quality were assayed: T1 (3 min at 80ºC) and T2 (45 s at 90ºC). Fresh blended unheated samples were used as control (CRL). The smoothie presented a viscoelastic behaviour. Thermal treatments reduced initial microbial loads by 1.3-2.4 and 1.4-3.1 log units, respectively. Samples were stored in darkness at 5 and 15ºC. Colour and physicochemical changes were reduced in thermal-treated samples throughout storage, which were better preserved at 5ºC rather than at 15ºC. Vitamin C changes during storage were fitted with a Weibullian distribution. Total vitamin C losses of T1 and T2 samples during storage at 15ºC were greatly reduced when they were stored at 5ºC. Initial total phenolics content (151.1 mg 29 kg-1 fw) was 44 and 36% increased after T1 and T2 treatments, respectively. The 3-p-30 coumaroyl quinic and chlorogenic acids accounted the 84.7% and 7.1% relative 31 abundance, respectively. Total antioxidant capacity (234.2 mg Trolox equivalent kg-1 fw) remained constant after the thermal treatments and was better maintained during storage in thermal-treated samples. Glucobrassicin accounted the 81% of the initial total glucosinolates content (117.8 mg kg-1 fw) of the smoothie. No glucosinolates losses were observed after T2 treatment being better preserved in thermal-treated samples. Conclusively, a short time–high temperature mild thermal treatment (T2) showed better quality and bioactive compounds retention in a green fresh vegetable smoothie during low temperature storage.