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

Universidade do Algarve, Фару, Faro, Portugal
Journal of Food Biochemistry (Impact Factor: 0.74). 12/2007; 31:715-725. DOI: 10.1111/j.1745-4514.2007.00138.x


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.
Aguardente de Medronho is a distillate in which its preservation, of great importance in the south of Portugal, is associated with its certification as a traditional product that is well defined and characterized. The information gathered during this study contributes to the understanding of the fermentation phase of this spirit's production in order to improve its fermentation and produce a consistent and high-quality final product. Now it is possible to suggest changes in the existing production process to enhance product quality and make it more competitive. This study aims in the first place to evaluate the microbiology and biochemistry of the fermentation process; second, it attempts to replace the natural fermentation with fermentations conducted with a well-defined cocktail containing several yeasts species.

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    • "Regarding the pH and tritratable acidity, P. spinosa was the most acidic wild fruit, with a titratable acidity value of 194.82 mL of NaOH N/10 per 100 g (and a pH around 3.43), followed by A. unedo, with an acidity of 92.37 mL NaOH N/10 per 100 g (and a pH of 3.37). These results are similar to the pH values reported by other authors in Portuguese samples of blackthorn (3.92) and strawberry-tree (3.74) fruits [29] [30]. R. ulmifolius fruits showed the lowest tritratable acidity value ( "
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    ABSTRACT: The edible fruits of four wild small trees or shrubs (Arbutus unedo, Crataegus monogyna, Prunus spinosa, and Rubus ulmifolius) traditionally consumed in the Iberian Peninsula were studied to evaluate their potential for human nutrition, considering their content in bioactive compounds. Lipophilic phytochemicals, such as fatty acids and tocopherols, as well as some hydrophilic antioxidants, such as vitamin C and organic acids, were analyzed. In addition, the antioxidant activity, measured as lipid peroxidation inhibition (β-carotene/linoleate and TBARS assays), was evaluated in each fruit. As far as we know, this is the first report relating to bioactive compounds in wild fruits with relation to the lipid peroxidation inhibition. Data revealed that these wild edible fruits are good sources of bioactive compounds as organic acids, vitamin C, tocopherols, and polyunsaturated fatty acids. They could be considered as functional foods or potential sources of bioactive compounds with antioxidant synergism effect, to be included as antioxidant food ingredients or in dietary supplements, mainly Rubus ulmifolius, due to its high content in tocopherols. This study provides useful and relevant information that justify tocopherols influence in the prevention of lipid peroxidation, due to the strong correlation observed (r>0.95) between these lipophilic bioactive compounds and the antioxidant activity.
    Full-text · Article · Feb 2013 · European Journal of Lipid Science and Technology
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    • "Thus, the high viscosity present in the arbutus berry pulps could interfere with the mass transfer, thus limiting the growth of the indigenous yeasts and, consequently, ethanol production (Alonso et al., 2010). A similar fermentation procedure was carried out by other researchers (Cavaco et al., 2007) to reproduce the little known fermentation phase of the production of Aguardente de Medronho, a distillate very appreciated in Portugal. In this case, the arbutus berry pulp was fermented by its wild microbiota during 36 days (as it is performed in the farms), to gain a better understanding of the fermentation process. "
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    ABSTRACT: The aim of the present study was to obtain two distilled alcoholic beverages from red raspberry and arbutus berry by solid-state fermentation and subsequent distillation of the fermented fruits. The mean concentrations of ethanol and volatile substances in the distillates from red raspberry (41.3 and 200.1g/hL aa) and arbutus berry (44.3 and 267.1g/hL aa) were higher than the corresponding minimum limits (38.5 and 200g/hL aa) fixed by the European Council (Regulation 110/2008) for fruit distillates. In addition, the mean concentrations of methanol in the two alcoholic beverages (113.9g/hL aa in case of red raspberry, and 320.5g/hL aa in case of arbutus berry) were much lower than the maximum levels of acceptability that the aforementioned regulation fixed for red raspberry (1200g/hL aa) and arbutus berry (1000g/hL aa) distillates. These results showed that both fruits can be used as fermentation substrates for producing two alcoholic beverages with high quality, which are safe for the consumers without any repercussion to their health from methanol concentrations.
    Full-text · Article · Jun 2011 · Food Research International

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