Chemical and microbial changes during the natural fermentation of strawberry tree (Arbutus unedo L.) fruits

Journal of Food Biochemistry (Impact Factor: 0.85). 01/2007; 31:715-725. DOI: 10.1111/j.1745-4514.2007.00138.x

ABSTRACT Aguardente de medronho is the name given in Portugal to a spirit made
from the fermented fruit of Arbutus unedo (strawberry tree), a plant grown
in the Mediterranean region. In order to gain a better understanding of the
fermentation process, as it is performed in the farms, a natural fermentation
with wild microbiota was carried out during 36 days, and some physicochemical
and microbiological parameters were studied. The microbial parameters
analyzed were total viable, lactic and acetic acids bacteria, and yeast counts.
The physicochemical parameters monitored were sugars, minerals, ethanol,
organic acids and pH. Yeasts were the main responsible for the fermentation
of the fruits, as the lactic and acetic acids bacteria are absent. As the fermentation
progressed, the sugars increased during the first 2 days and gradually
decreased along the fermentation period. Maintaining the good quality of the
product could contribute to the preservation and valorization of traditional
resources that are of great importance to prevent their disappearance.

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    ABSTRACT: Arbutus wild berries have been traditionally collected and appreciated in the Mediterranean region, although it is actually considered an underutilized fruit-tree species. Increasing the scarce knowledge about its nutritional composition and natural production may interest a broad range of scholars, such as ethnobotanists, chemists, nutritionists and anthropologists. The present study aims to provide original data on the nutritional value and the biomass production of wild strawberry-tree fruits, studying the variation of these characteristics in fruits harvested in different years, from two different Spanish areas. Macro and micronutrient composition of mature Arbutus unedo fruits have been analyzed, with particular attention to the content of some bioactive compounds (fiber, vitamin C as ascorbic and dehydroascorbic acids, total phenolics, carotenoids, including lycopene) and the organic acids profile. The contribution to recommended dietary allowances (RDAs) of this exotic fruit has also been calculated. Fruit crop volume per tree has been estimated as well in the wild strawberry-tree populations surveyed to provide a general framework for discussing the agronomic potential of the species. A wide variability in the nutrient composition of strawberry-tree fruits was found which shows that the analysis of many different samples from different origins and seasons are required to provide average reliable data about the chemical composition of wild fruits. From the results obtained, strawberry-tree fruits can be considered a very good source of health promoting compounds as vitamin C and dietary fiber (202.6 mg/100 g and 42.6% minimum contribution to RDAs, respectively). They are also rich in total available carbohydrates, sugars, potassium and secondary metabolites, such as phenolic compounds, being poor in lipids and Na. These results, together with its high production may help to reinforce its consumption, as an alternative to the fruits available in the market or a source of bioactive compounds for dietary supplements or functional foods.
    Food Research International 06/2011; 44(5):1244–1253. · 3.05 Impact Factor