Development of new non-dairy beverages from Mediterranean fruit juices fermented with water kefir microorganisms

The aim of this work was to explore the use of several Mediterranean fruit juices as fermentable substrates to develop new non-dairy fermented beverages. Microbiological, chemical and sensory features of kefir-like beverages obtained after the fermentation of juices extracted from fruits cultivated in Sicily (southern Italy) with water kefir microorganisms were investigated. Results indicated that both lactic acid bacteria and yeasts were able to develop in the fruit juices tested, but the highest levels were registered with prickly pear fruit juice. All fruit juices underwent a lactic fermentation, since a lactic acid content was detected in the resulting kefir-like beverages. Except kiwifruit and quince based kefirs, total titratable acidity increased for the other experimental products. A general decrease of the soluble solid content and an increase of the number of volatile organic compounds (VOCs) was also observed after fermentation. As expected, the fermentation increased the concentration of alcohols. The main fermentation in KLBs resulted to be yeast-based. Kiwifruit and pomegranate juices possessed a high antioxidant activity. Esters compounds were present at higher amount after the fermentation, especially in grape, pomegranate and quince. Aldehydes showed an opposite trend. Changes in colour attributes were registered as noticeable at human perception scale. The overall quality evaluation indicated that, among the Mediterranean fruit juices tested, apple and grape beverages were the products mostly appreciated by the tasters. Therefore, these findings support the possibility to develop fruit-based kefir-like beverages with high added value and functional properties. © 2015 Elsevier Ltd

Chemical composition of the leaf essential oil of grapefruits ( Citrus paradisi Macf.) in relation with the genetic origin

International audienceThe composition of twenty-four samples of essential oil isolated from leaves of Citrus paradisi Macf. growing in a northern area of citrus cultivation in Mediterranean climate (Corsica) was investigated by GC (RI), GC-MS and C-13 NMR. Thirty-six compounds accounting for 94.9-99.3% of the oil composition were identified. The oils contained mainly monoterpene hydrocarbons and specially sabinene (up to 60.2%),(E)-beta-ocimene (up to 15.0%) and punctually gamma-terpinene (up to 56.1%), beta-pinene (up to 30.9%) and p-cymene (up to 12.5%). The twenty-four compositions were submitted to k-means partitioning and principal component analysis, which allowed the distinction of one homogeneous group of twenty-two grapefruits (main compound sabinene, mean = 47.1%). This group included eighteen cultivars derived by mutation from the ancestral grapefruit tree (Duncan) and four cultivars known to be interspecific hybrids. Two out group cultivars were clearly differentiated from others by original chemical compositions, in agreement with their hybrid origin

Seasonal variations of antimicrobial activity and chemical composition of essential oils extracted from three <i>Citrus limon</i> L. Burm. cultivars

<div><p>In order to investigate the seasonal variations of antimicrobial properties and chemical composition of essential oils (EOs), three different cultivars of <i>Citrus limon</i> L. Burm. spp. (Femminello Santa Teresa, Monachello and Femminello Continella) were collected at 6-week intervals, from December 2012 to April 2013, for a total of four harvests. The EOs were extracted from lemon peel by hydro-distillation. The antimicrobial activity, tested by paper disc diffusion method, was evaluated against common food-related pathogenic bacteria (<i>Listeria monocytogenes</i>, <i>Staphylococcus aureus</i>, <i>Salmonella enterica</i> and <i>Enterobacter</i> spp.). EOs were more effective against Gram-positive than Gram-negative bacteria at each collection time, but a strong strain dependence was evidenced. Monachello EOs showed the highest inhibition power. The chemical characterisation of the EOs performed by gas chromatography/mass spectrometry identified from 36 to 42 molecules. The chemical difference registered among samples and seasons may explain the different antimicrobial efficacies recorded.</p></div