Table 3.
Evaluation of antioxidant activity (AOA) of fruits and vegetables subject to freezing pre-treated with cryoprotectants.
| Food | Product Type (Whole, Puree) | Freezing System | Freezing T (°C) | Storage T (°C) | Storage Times | Cryoprotectant | AOA Test | Effect on Antioxidant Biomolecules | References | ||
|---|---|---|---|---|---|---|---|---|---|---|---|
| apple | puree | lab freezer | −18 | −18 | 6 months | Sucrose, Glucose, Fructose, Trehalose (1%, 5%; w/w) | ABTS | DPPH | Positive effect on phenolic profile of Fuji variety by Sucrose (5%), Trehalose (5%) and Glucose (5%) during frozen storage. Contradictory results for Idared variety phenolic profile | [130] | |
| puree | home freezer | −18 | ns | Sucrose, Glucose, Fructose, Trehalose (1%, 5%; w/w) | ABTS | Higher polyphenols retention observed in freeze-dried samples added with Fructose (1%) and Trehalose (1%). Higher polyphenols retention observed in frozen samples added with Sucrose (5%) and Trehalose (5%) |
[131] | ||||
| arazá | puree | nr | −20 | −20 | 1, 2, 3, 4 months | Sucrose (20%; w/w) | ABTS | DPPH | FRAP | Sample added with Sucrose (20%) showed higher total phenolic content and vitamin C concentration during frozen storage | [187] |
| blackberries | whole | nr | −18 | −18 | 11 months | Sucrose, Fructose, Glucose, Fructose:Glucose, Fructose:Sucrose (50%; w/w) | DPPH | Fructose and Glucose had a positive impact on total phenolic content and anthocyanins retention. Discordant effects observed on vitamin C retention | [135] | ||
| (sour) cherry | puree | nr | −18 | Room temperature after freeze-drying | 30 days | Maltose, Sucrose, Trehalose (5%, 10%, 20%; w/w) | ABTS | DPPH | FRAP | Negative effect of sugars on total phenolic and flavonoids content. Discordant results on single anthocyanins retention, Maltose (20%) was the only sugar showing a positive effect on anthocyanins preservation | [186] |
| cherry | whole | Air blast freezer | −50 | −20 | ns | Glucose:Fructose (2:1 ratio, solution 60%; w/w) | DPPH | - | [185] | ||
| whole | nr | −20 | −20 | 31 days | Antifreeze proteins | DPPH | Addition of ice structuring proteins better preserved total phenolic and anthocyanins content | [178] | |||
FRAP: Ferric Reducing Antioxidant Power; ABTS: 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) radical cation assay; DPPH: 2,2-diphenyl-1-picrylhydrazyl free radical assay; nr: not reported; ns: no storage.