Quality preservation and safety ensurement of a vegetable smoothie by high‐pressure processing

Abstract

This research aims to evaluate the effect of a previously optimized high‐pressure processing (HPP) treatment on the vegetable smoothie stability during 28 days at 5 °C and on the inactivation of a contamination with Listeria monocytogenes and Escherichia coli O157:H7 surrogates during 12 days at 15 °C. HPP (630 MPa/6 min) reduced native microbiota to values below detection limit (DL = 1 log CFU/g) and significantly reduced polyphenol oxidase, peroxidase, and pectin methylesterase initial activities (16.7%, 29.6%, and 70.7%, respectively), maintaining significant lower values than control during storage. In addition, smoothie's soluble solids and pH were neither modified with treatment nor storage time, while greater retention of color and nutritional indicators was noted on treated samples during storage. Moreover, HPP allowed controlling 6 log CFU/g surrogate counts, maintaining them below DL during storage. Hence, optimized HPP treatment is effective to improve the quality stability of the product besides ensuring their safety when contamination occurs. Practical applications High‐pressure processing is an alternative preservation method that not only is effective for microbial and enzymatic control but also has demonstrated promising results in antioxidant and bioactive compounds preservation, which is of especial relevance in foods such as fruit and vegetable smoothies that contain large amount of them. Recently, smoothies have gained strength in the market as part of the trend toward healthy eating habits. However, there is little information available on the effect of conservation technologies on this type of matrix. This is one of the first studies addressing the effect of high hydrostatic pressure processing during the storage of mixed fruit and vegetable smoothies, providing information of great interest for an industry in full growth.

Smoothie Drinks: Possible Source of Resistant and Biofilm-Forming Microorganisms

“…Many earlier studies also report the significant occurrence of, e.g., enterobacteria in smoothie drinks at levels of 1.9 log CFU/mL [ 32 ], 2.4 log CFU/mL [ 33 ], 3.39 log CFU/mL [ 34 ] and even 5.5 log CFU/mL [ 35 ]. The analysis of ten smoothie samples purchased in the Czech Republic revealed the presence of coliform bacteria in the range of 1.5–6.0 log CFU/mL, which basically corresponds to previously published results of studies from Argentina and Spain [ 32 , 33 , 35 ]. Enterobacter bugandensis , Klebsiella variicola and Klebsiella pneumoniae were among the most frequently detected representatives of coliform bacteria.…”

Impact of High-Pressure Processing on Antioxidant Activity during Storage of Fruits and Fruit Products: A Review

“…In general, HPP has been shown to have minor or no significant effect on micronutrients [ 149 ] and on total the carotenoid content within vegetable matrices [ 150 ]. In general, HPP treatments below 50 °C caused no degradation of ascorbic acid in fruit preparation products [ 134 , 135 , 141 , 142 , 151 , 152 ]. Regarding total flavonoids, there are contradictory results: Nayak et al [ 133 ] reported the decrease of these compounds was less after pressurization, in comparison to heated samples; other work reported a similar decrease after storage in both HPP and thermal processing samples [ 96 ]; and Vieira et al [ 137 ] showed that HPP caused a decrease of 39.3%.…”

“…Fernández et al [ 151 ] formulated a smoothie with the following composition (weight): orange juice (59%), apples (15%), carrots (15%), beet leaves (6%), and beet stems (5%), which was treated with HPP (630 MPa for 6 min). Initially, HPP-treated samples presented higher values of ascorbic acid and total phenolics (about 7%) than in the control ones, and then a decrease took place with the storage time for both type of smoothies.…”

“… [ 100 ] Mixed fruit and vegetable smoothie HPP: 630 MPa, 6 min, 22 °C Storage: 28 days, 5 °C Ascorbic acid: HPLC-DAD (mg AA/kg smoothie) TPC: Folin-Ciocalteu (mg GAE/kg smoothie) DPPH (μmol Trolox/kg smoothie) FRAP (μmol Trolox/kg smoothie) Increase in the initial values of nutritional quality indicators and decrease during refrigerated storage. [ 151 ] Mixed fruit and vegetable smoothie HPP: 630 MPa, 6 min, 22 °C Storage: 28 days, 5 °C TPC: Folin-Ciocalteu (mg GAE/100 g smoothie) DPPH (μmol Trolox/100 g smoothie) FRAP (μmol Trolox/100 g smoothie) Increase in the initial values of antioxidants indicators and decrease during room storage. [ 161 ] Orange vegetables smoothie HPP: 0, 300, 400, 500 and 600 MPa, 5 min, 23 °C Storage: 7 days, 5 °C TPC: Folin-Ciocalteu (mg chlorogenic acid/kg) TPC increased in all samples, mainly at 300–400 MPa.…”

Chemometric Comparison of High-Pressure Processing and Thermal Pasteurization: The Nutritive, Sensory, and Microbial Quality of Smoothies

“…In contrast to thermal treatment, HP was found to keep the visual color much closer to that of the untreated smoothie [ 21 ]. While thermal pasteurization (P) could negatively affect the stability of the BACs in smoothies [ 22 ], a recent study showed that HP could even increase the baseline levels of nutritional quality in vegetable smoothies during cold storage [ 23 ]. Moreover, HP was found to be a less destructive treatment in terms of the vitamin C stability, compared to thermal processing, which could reduce vitamin C content by 35–44% [ 24 ].…”