HP-processed smoothies at a range between 450 and 650 MPa
show a significant reduction in aerobic mesophilic microorganisms,
yeast and moulds, and their shelf life is extended to over 45 days at
4 C. No microbial counts were observed after applying thermal or
any high-pressure processing. Microbial reduction during storage
improved as pressure treatment increased (600, 650 MPa). HPP
does not modify the main physicochemical and chemical compounds,
individual sugars, organic acids and minerals analysed.
Smoothies treated with HPP may conserve their sensory attributes
better eparticularly in terms of aroma and overall acceptabilitye
than with thermal processing. HP processing may be a better choice
for the preservation of microbial and sensorial qualities. These results
prove the suitability of HPP as an alternative to traditional
thermal methods of treating smoothies.
Smoothies are an excellent way to intake nutrients and bioactive compounds from both the fruits and the
milk or soymilk with which they are made. High pressure processing (HPP) is an efficient alternative to
traditional thermal pasteurization (TP), obtaining microbiologically-safe smoothies with minimum
impact on nutritional and sensorial properties. Untreated, pasteurized (80 C/3 min) and HPP (450
e650 MPa for 3 min at 20 C) milk- and soy-smoothies were compared. Milk- and soy-smoothies showed
a total reduction in microorganisms after pasteurization and HPP at the pressure conditions applied. HPP
maintained microbial stability until the end of the storage period (45 days at 4 C). Soluble sugars
(glucose and fructose), organic acids (citric, malic, tartaric, oxalic and quinic) and minerals (sodium,
potassium, calcium, magnesium, iron, copper, zinc and manganese) showed no significant changes after
the treatments and storage. No significant differences were found in sensorial attributes between untreated
and HPP samples, although the aroma and acceptability scores decreased significantly for
pasteurized smoothies. Based on the data obtained, 450 MPa are sufficient to obtain safe smoothies
whose organoleptic properties are equally acceptable to consumers as freshly-made smoothies.