What happens with the strawberry during processing and subsequent storage? Kjersti Aaby Nofima Food, Matforsk as Food, Fisheries and Aquaculture Research, Norway
Background and aims of the study Diets high in fruits and vegetables are associated with lower risk of chronic diseases Polyphenols are present in high concentrations in plant-derived foods and may contribute to the observed health benefits A substantial proportion of berries, such as strawberries, are consumed as processed, stored products. Compare fresh and stored strawberry purees as regards content of ascorbic acid, phenolic compounds and antioxidative properties
Background and aims of the study During production of juices and seedless purees, the berries are separated into various fractions and localization within plant material becomes important Determine the contribution of achenes to polyphenol content in strawberries and strawberry purees
Achenes, the real fruits of the strawberry Ascorbic acids Flavonoids, includinganthocyanins Ellagic acid derivatives (ellagitannins) Cinnamic acid derivatives Hydroxybenzoic acids Contribution (%) of anthocyanins and ellagitannins to polyphenol content in: Anthocyanins Ellagitannins Flesh a 5% (5 mg/1 g fw) 1% (1 mg /1 g fw) Achenes a,b 6% (55 mg/1 g fw) 65% (64 mg/1 g fw) a cv. Totem and Puget Reliance b Removed manually Aaby et al.j. Agric. Food Chem.25, 53, 432-44
The distribution of weight, polyphenols and antioxidant capacities in achenes and flesh of strawberries Distribution (%) 1 8 6 4 2 Achenes Flesh Weight Total anthocyanins Total phenolics FRAP ORAC Ellagitannins The achenes contributed only 1% to the weight of strawberries, but about 12% to total phenolic content
What happens with the constituents in the strawberry a when it becomes puree? 1 8 85 8 8 76 88 % remaining 6 4 55 2 L-ascorbic acid Anthocyanins Ellagitannins Total phenolics FRAP ORAC a cv. Senga Sengana Aaby et al.j. Agric. Food Chem.27, 55, 5156-5166
4 3 2 1 5 4 3 2 1 What happens with the constitutents in the purees during storage? 6 C 22 C 8 16 Time (weeks) 6 C 22 C 8 16 Time (weeks) 2 15 1 5 8 16 Time (weeks) Total anthocyanins (mg/1 g fw) Total ascorbic acid (mg/1 g fw) Total phenolics (mg GAE/1 g fw) 24 2 16 12 8 4 Ellagitannins (mg/1 g fw) 8 16 Time (weeks)
Contribution of different compounds to AOX in strawberry purees FRAP (mmol/1 g fw) 3. 2. 1. Anthocyanins Ascorbic acids Remaining compounds. At production 8 weeks at 6 C 16 weeks at 6 C 8 weeks at 22 C 16 weeks at 22 C
How does achene levels effect polyphenol content in strawberry purees? Concentration (mg/1 g of fw) 5 4 3 2 1 Flesh Berry Achene AA TMA Ellagitannins Purees made from flesh, berry homogenate and achene-enriched berry homogenate, containg, 1, and 2.9% achenes, respectively
What is the effect of achene levels on polyphenol content in strawberry purees during storage The anthocyanins, total phenolics and FRAP were better preserved in purees with higher achene contents TMA (mg/1 g fw) 4 3 Flesh Berries Achene-enriched 2 8 16 Storage time (weeks)
Summary what happened with the strawberry during processing and storage During processing and storage of strawberry purees; ascorbic acids and anthocyanins decreased rapidly other phenolic compounds and AOX were quite stable The achenes contributed significantly to increased levels and stability of many phenolic compounds in strawberry purees The consequences for health of the changed antioxidant profile caused by processing and storage, that is, the effect of native components versus degradation compounds, remains to be elucidated