ISSN 2285-1364, ISSN CD-ROM 2285-5521, ISSN ONLINE 2285-1372, ISSN-L 2285-1364
 

Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVII
Written by Andreea STAN, Mona Elena POPA

Numerous studies have documented the prevention of certain chronically diseases, e.g. hypertension, coronary heart diseases, and the risk of stroke by consuming an adequate amount of fruits and vegetables.To increase the intake of phytochemicals, the food industry offers smoothies as an alternative or addition to the consumption of fresh fruits.Their production is based on the usage of the entire fruit, which is processed from pulp to puree, the seeds and the peel being removed. To develop different flavors and to obtain the appropriate texture of the final product the juice from the corresponding fruits is used as well. Smoothie products are characterized by a high concentration of nutrients and a low content of energy.The aim of this study is to develop new high quality products based on mixtures of pressed and squeezed fruit without adding preservatives, stabilizers or chemical correctors of pH and acidity. For this purpose, some mixtures of several pressed fruit like apples, pears, bananas, mango, peaches, cherry, strawberries and orange, maracuja, apples or grapes juices, have been made.The sensorial analysis tests have shown that a Brix degree equal with 13 and a pH smaller than 4, are the ideal values for the microbiologic stability of the newly developed products. These values have been corrected by the addition of grape juice for the samples with a low pH and a low Brix degree and by the addition of orange juice for the samples with a high pH and a high Brix degree.The structure and the physico-chemical properties of the smoothies have an essential role in the increase of taste as well as the sensorial perception of the consumers. The texture is a critical attribute of quality which influences the consumer’s acceptance of the smoothies, being in this way of a major interest in the development of the product

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Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVII
Written by Florentina HUTANU, Emilia OCNARU, Melania-Liliana ARSENE, Mihaela BADEA-DONI

The development of a highly selective and sensitive sensor for H2O2 in beverages such as natural juices, is described in this work. The sensor is based on the deposition of Prussian Blue (PB) onto screen-printed carbon electrodes (SPCEs) followed by the electropolymerization of a non-conducting film. Several procedures for PB deposition on the SPE electrodes were tested: electrochemical deposition (potentiostatic, cyclic voltammetry) and chemical deposition. The electrochemical and analytical properties of the SPCE/PB sensors had been evaluated and the potentiostatic method for PB deposition was selected for the further development of the H2O2 sensor. In order to develop a robust sensor for H2O2 determination in samples with complex matrix, we covered the PB layer with an electropolymerized nonconducting film with a high permselectivity for H2O2. This film is a copolymer based on 2,6-DHN (2,6- dihydroxynaphtalene) and APEA (2-(4-aminophenyl)-ethylamine). The SPCE/PB/copolymer sensor demonstrated improved stability in operational conditions and excellent interference rejection properties. This sensor may be successfully applied on-field, using a portable potentiostat-galvanostat and the chronoamperometry technique, as well as in a laboratory bench flow injection analysis system with amperometric detection. The developed sensor was able to measure H2O2 in the linear range 1 M – 500 M (R=0.9989), with a detection limit of 0.5 M. The SPCE/PB/copolymer sensor maintained for a long period its response for H2O2 (94% response was retained after 60 days).

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Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVII
Written by Alexandra GHIORGHITA, Gheorghe CÂMPEANU, Vasilica MANEA, Misu MOSCOVICI, Eugenia MOCANU, Corina IONESCU

The study of lipolytic enzymes has shown great scientific interest in modern biotechnology researches, due to the discovery of applications such as transesterification and ester stereospecific hydrolysis, used in oil industry, detergents and pharmaceutics. Enzyme catalysis using lipases has been intensely researched since the reaction takes place at regular pressure and 30-40oC, achieving the necessary energy, and reducing at the same time the emergence of unwanted secondary compounds. Lipases used in biotechnology processes are usually microbial in origin and are commercially available, immobilized on different supports. They present the advantage of the possibility of both recycling the biocatalyst and also developing continuous processes. In biotechnological processes, the most exploited lipase is lipase B from Candida antarctica. Given the price of such enzymes, there is a continuous need for novel and better enzymes to be used in biocatalysis reactions. To this purpose, a series of industrial importance strains pertaining to the Microorganisms Collection of the National Institute for Chemical Pharmaceutical Research and Development ICCF Bucharest have been tested in order to determine potential lipase production. The screening was performed on 3 bacterial strains, 16 yeast strains and 14 fungi strains. The microorganisms were grown on several specific lipase inductor media. The enzymes produced by the strains which developed lipolytic activity are to be used later for biodiesel obtainment through biocatalysis.

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Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVII
Written by Alexandra GHIORGHITA, Gheorghe CÂMPEANU, Vasilica MANEA, Angela CASARICA, Calina Petruta CORNEA

In reaction to expanding markets and increasing demand for novel biocatalysts, commercial enzyme production has been continuingly growing during the last century. Although some enzymes are extracted from plants and animals, the major source of industrial enzymes consists in microorganisms. Obtainment of a new microbial enzyme begins with a screening of microorganisms for the desired activity, using specific methods of selection. Lipases or glycerol-ester hydrolases are carboxyl-esterases which catalyze hydrolytic cleaving of glycerol esters with fatty acids.Microorganisms are rich sources of lipases, especially yeast strains pertaining to the genus Candida. Yeast strains from the CMII-WFCC232 industrial interest strain collection of the National Institute for Chemical Pharmaceutical Research and Development ICCF Bucharest have been studied regarding their lipase production. Specific screening media have been used in order to stimulate lipolytic activity in the yeast strains. Viability and presence of opaque areas on Petri dishes containing fatty acid esters and lipase inducers as proof of enzyme activity have been determined. The strains which presented lyoplytic activity have later on been cultivated on specific liquid medium and enzymatic activity has been determined.

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Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVII
Written by Emilia OCNARU, Melania ARSENE, Gelu VASILESCU, Mihaela BADEA DONI

For nitrite determination in cured meat, we have developed an original amperometric method based on a modified sensor surface using nonconductive polymers. The nonconductive films allow the target analyte to cross the sensor surface where an electrochemical reaction is taking place, albeit, restricting intereferences. Compared to a spectroscopic method, which requires a stringent pH control and the use of carcinogenic reagents, the amperometric method for nitrite determination is simple, rapid, and does not require dangerous reagents. The polymeric films were deposited onto the Pt and carbon paste electrodes, using cyclic voltammetry. The monomers used for nonconductive polymer film development were: 2,6-dihydroxynaphtalene (2,6-DHN), o-dianisidine (o-DIA) and 1,8-diaminonaphtalene (1,8-DAN). From all the permselective membrane that we have studied, the 2,6-DHN/Pt based sensor presents the sensibility and endurance required for developing the further studies for nitrite detection using a batch and a flow injection analyse system (FIA). Electrochemical tests have shown that 2,6-DHN/Pt is sensitive for sodium nitrite detection, it restricts potassium ferricyanide crossing, and acts as a barrier against ascorbic acid interference. Ascorbic acid is a major interferent in food products.The 2,6-DHN/Pt has a linear range (5-200μM), a correlation factor of 0.9994, and a low detection limit (2.5μM, S/N=3). Such a sensor has the ability to detect nitrite in various meat samples (e.g., hot-dogs, ham, italian salami, and canned beef).

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Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVII
Written by Vlad Ioan POPA, Elena TANASE, Mihaela GEICU-CRISTEA,Cristian-Andi NICOLAE, Raluca Augusta GABOR

The quality of fresh meat is an extremely important characteristic influencing the consumer's purchase decision. The behavior of biodegradable tray in contact with meat is important also for food chain logistic management. The stability of this system meat-biodegradable tray is depending by a variety of factors and can be monitored through physicchemical and microbiological assessment of meat on the one hand and tray material behavior on the other hand. The effect of chilling temperature on both meat and tray material have been experimented in this work. For this purpose,Longissimus dorsi from pork carcass was packed in biobased trays and stored at 4oC ±1 for 7 days. During the chilled storage physic-chemical analysis as pH, color, dry matter content, aw, titratable acidity, presence of hydrogen sulfide,ammonia in the free state and microbiological analysis as total plate count, number of yeasts and moulds, coliform bacteria, the enterobacteriaceae, Salmonella sp., also thermo gravimetric analysis (TGA-DTG), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and Fourier transform infrared spectrometry (FTIR) of biobased trays were performed. Thermal analyzes showed no changes in the properties of polymeric materials used in the manufacture of food trays. FTIR and TGA analysis revealed the occurrence of some deposits consisting especially in moisture and organic material on the inside of the food trays.

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Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVII
Written by Caterina TOMULESCU, Eugenia MOCANU, Misu MOSCOVICI, Gabriela SAVOIU, Maria PETRESCU, Nicoleta DOBRE

Diacerein (DCN) is an anti-inflammatory, non-steroid drug with an analgesic effect, used in the treatment of osteoarthritis. DCN is pharmaceutically formulated as a yellow powder in capsules for oral use and it is mainly obtained from extracts of Rheum Emodi (rhubarb) and Aloe Vera. The pollution with pharmaceutical products represents one of the main interests in environmental protection. The influence of DCN was tested on different strains of bacteria and yeasts, common species that can be found in water and soil, and play an important part in decomposing chemical pollutants. The direct action of the pharmaceutical powder evenly spread or dispersed in solid specific culture media was evaluated. In liquid media in which different DCN concentrations were added, the microbial growth and DCN metabolization were analyzed using spectrophotometric methods. On solid media, DCN ioaccumulated in the microorganism colonies, giving them an orange colour depending on their specificity. In liquid media, DCN had an inhibitory effect or was an enhancer of the pigments colour naturally secreted by some strains of bacteria.

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Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVII
Written by Luminita VISAN, Ricuta DOBRINOIU

The Sauvignon variety is part of the grape varieties semi-aromatic; the flavor is not given by the terpenes, as the aromatic varieties (muscat) but is given by other compounds, found in grapes under the form of precursors flavor,odorless thiols and after the alcoholic fermentation are converted in corresponding aromatic thiols. The volatile compounds that participate at the Sauvignon flavor, according to some authors are mercaptans and especially the 4-mercapto-4-metylpentan-2-one and after others is methoxypyrazine, compound with a decisive role in the variety flavor.There were analyzed three Sauvignon wines from the wine region Dealu Mare, vintage from 2007, 2008 and 2011. The wines were analyzed physico-chemical and analytical technique of GC/MS. In the Sauvignon case of the 2011 year there was identified and determined quantitatively with the GC/MS method, three compounds from the mercaptans group with role in the Sauvignon aroma: 4-mercapto-4-metylpentan-2-one, 3-mercaptohexan-1-ol and 3-mercaptohexyl acetate. The results led to the identification and dosing of seventeen volatile compounds. In the highest concentration was found phenyl-2-ethanol, made with rose flower scent. From the esters prevail the 2-hydroxy-ethyl propanoate and ethyl acetate. Regarding the mercaptans the results show that they have an important role in the flavor of Sauvignon, the determined concentrations are grater than their threshold of perception.

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Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVII
Written by Luminita VISAN, Ricuta DOBRINOIU

The chromatic profile of red wines are formed by the participation of various compounds phenolic: anthocyanins,tannins, flavones and phenolic acids, anthocyanins are polyphenolic substances with the most imported role in the color of young wines. The evolution of red wine leads to changes of structures and chromatic properties of wine due to polymerization reactions, condensation and oxidation. Also the red wine color is strongly influenced by wine region of origin, the wine grape variety and vintage year. There were studied chromatic characteristics of red wines as Merlot and Feteasca Neagra from two different vineyards in terms ecopedoclimatics, Dobrogea and Moldova, the 2008 year harvest. The polyphenolic composition of wines was judged by the content in polyphenols, tannins and anthocyanins. A wine tannin structure was analyzed by their concentration in condensed tannins, astringent tannins and tanninpolysaccharide complex. Analyzes have been carried out in the wine by UV-VIS spectrometry techniques. Total content of polyphenols have been determined by IPT technique. Tannins have been determined by the Ribereau-Gayon method (1996), tannin structure after Glories (1978) method; anthocyanins were determined by the discoloration technique with SO2. Color intensity was determined at λ=420 nm and λ=520 nm. The study on color of red wines analyzed during their evolution referred to the study of chromatic parameters, the content of anthocyanin monomers and polymers (Glories method).

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Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVII
Written by Luminita VISAN, Ricuta DOBRINOIU

Dry-fermented sausages and dry-cured ham, constitute one of the most representative traditional foods represents meat products, which have a high variety of flavors and textures, represent an important part of local economies, particular cultures and gastronomic heritages.Purpose of this paper is to present present comparative physical, chemical and biochemical changes that occur during maturation of three products maintained under the same conditions: Plescoi sausages, Chorizo salami and Prosciutto.The drying removes 38,8 to 58,8%, while amino acids content increased between 1.87 and 2.52 times. pH variation was small because fermentation without starter was chosen.

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