The global beverage market is reportedly set to reach a staggering $1.3 trillion by 2017 and although there are long-established products dominating the market, there is still room for innovation. If this innovation can result in reducing food waste as well as producing an attractive flavorsome drink with beneficial health properties, it is potentially a recipe for success. In this blog post we will look at functional beverage testing and how for a number of years Spanish researchers have been investigating the properties of beverages fermented from strawberry pulp.
Anthocyanin in Strawberries
As strawberries are extremely perishable, with very short shelf-life, the rationale is to reduce waste from surplus strawberry production by producing a beverage using fermentation as a form of preservation coupled with pasteurization. Fermentation is carried out with an inoculum of acetic acid bacteria for the selective conversion of glucose in the strawberry puree into gluconic acid. The resulting beverage is non-alcoholic and has the added benefit that it is suitable for diabetics as there is no residual glucose after fermentation. Recent research by Carmen García-Parrilla and co-workers from University of Seville in the Journal of Functional Foods has focused on bioactive anthocyanins in these added-value fermented strawberry beverages.
Pelargonidin 3-glucoside is the major anthocyanin in strawberries which generally contain from 153–652 mg/kg fresh weight, followed in importance by pelargonidin 3-rutinoside and other pelargonidin and cyanidin derivatives.
In order to establish if any changes in anthocyanin profiles occur during fermentation and processing of strawberries, beverage extracts were studied using an Dionex Ultimate 3000 UPLC connected to a quadrupole Q-Exactive™ hybrid mass spectrometer (UHPLC-MS/MS Orbitrap™ system).
Anthocyanin identification and quantification was carried out in positive ion mode by scanning from m/z 100– 1500 at 35,000 resolution and by targeted MS/MS acquisitions. Compounds were identified according to their mass spectra, calculated mass, characteristic fragmentation and retention times. These complex compounds with molecular masses ranging from 449 to 721 were readily analyzed after simple extraction and cleanup using an Amberlite column, utilizing the power of accurate mass spectrometry for unequivocal identification and measurement. In addition to measuring established anthocyanins, LC-HRMS also enabled tentative identification of four novel bioactive compounds not been previously reported as occurring in strawberry or strawberry products.
A future beverage analysis?
Whilst for the analytical chemist, anthocyanin profiles and identification of novel bioactives are academically interesting, in practical terms the important findings relate to the effects of storage temperature and time for this strawberry beverage. In terms of maintaining both the anthocyanin profile and color of the beverage, refrigeration was found to be necessary to preserve bioactive compounds. It was found that the beverage half-life for preserving its composition and properties was 60 days when stored at 4°C, a significant extension of shelf-life compared to fresh strawberries. This work yet again demonstrates the intrinsic role that state-of-the-art food analysis plays in underpinning developments in food science and technology. The consumer will be the ultimate beneficiary of this work when a novel functional food strawberry drink hits the marketplace.