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    ABSTRACT: Pandoro is a traditional Italian sweet-leavened baked product, usually consumed at Christmas. It is manufactured according to specific procedures and preparation starts from a sourdough called ‘‘madre’’ (mother sponge) continuously refreshed. This sourdough is the result of a complex microbial association including yeasts and lactic acid bacteria (LAB) and its use can improve sensory quality and shelf-life of the resulting products. The aim of this work was to evaluate the effect of the use of two different sourdoughs matured at different temperature (13 and 19 °C) on some metabolites, which can affect the organoleptic characteristics of Pandoro. Different samples, taken throughout the 19 h of process, were analysed for the determination of yeast and LAB counts, pH, aw, carbohydrates, organic acids content and volatile profile. The results showed that, at the end of fermentation process, the sourdough propagated at 19 °C reached lower pH values than that at 13 °C. This was probably due to higher LAB counts (1 log unit higher), resulting also in higher lactic acid concentration and faster sugars depletion. On the contrary, temperature of dough during maturation did not affected yeast concentrations. Different production processes strongly affected also the volatile profile, both of sourdough at the end of fermentation and of the final products.
    LWT - Food Science and Technology. 11/2014; 59(1):289–299.
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    ABSTRACT: Salama da sugo is a fermented sausage from Ferrara tradition (Italy, Emilia-Romagna region), subjected to a long ripening period (4-6 months) and characterized by a high content of wine and spices in the mixture. It can be consumed after cooking and it is served with its sugo, i.e. the liquid extracted by cooking process. The aim of this work is the setting up of a method for the sensory profile of Salama da sugo, whereas it has been requested to the European Commission the Protected Geographical Indication (PGI).
    Journal of the Science of Food and Agriculture 06/2014; · 1.76 Impact Factor
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    ABSTRACT: The aim of this work was to characterize the essential oil (EO) of Eryngium foetidum (EfEO) and assess its activity toward Listeria monocytogenes in broth and during thermal inactivation of the pathogen in pineapple juice. In this respect, EfEO was chemically characterized, and its antilisteria potential in broth as a function of pH, cell load, and EfEO concentration was assessed through a central composite design. Furthermore, the inactivation kinetics of L. monocytogenes in the juice were assessed by combining EfEO and low pasteurization temperatures. A total of 81 compounds were identified from EfEO. The reduction of pH and cell load increased EO activity. The use of only 15 ppm of EfEO during pasteurization of pineapple juice at 60°C reduced the time required for a 4-log reduction in L. monocytogenes CFU/ml by 74.9% (i.e., from 8.5 to 2.1 min) compared with treatment without EfEO. It could be concluded that EfEO activity toward L. monocytogenes increases with the reduction of pH and that it can be used at sublethal concentrations in combination with low temperatures in pineapple juice pasteurization. This study demonstrates that EO-assisted pasteurization is a promising strategy for the reduction of thermal impact during juice production. EfEO is easily available and compatible with many juices and is thus promising for industrial application.
    Journal of food protection 03/2014; 77(3):435-43. · 1.83 Impact Factor
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    ABSTRACT: Nine Leuconostoc mesenteroides phages were isolated during blue cheese manufacture yielding faulty products with reduced eye formation. Their morphologies, restriction profiles, host ranges and long-term survival rates (25°C, 8°C, -20°C and -80°C) were analysed. Based on restriction analysis, six of them were further examined regarding resistance to physical (heat and high pressure homogenization, HPH) and chemical treatments (ethanol, sodium hypochlorite, peracetic acid, biocides A, C, E and F). According to their morphology, L. mesenteroides phages studied in the present work belonged to the Caudovirales order and Siphoviridae family. Six distinct restriction patterns were obtained with EcoRV, HindIII, ClaI and XhoI enzymes, revealing interesting phage diversity in the dairy environment. No significant reductions in phage counts were observed after ten months of storage at -20°C and -80°C, while slightly and moderate decrease in phage numbers were noticed at 8°C and 25°C, respectively. The phages subjected to heat treatments generally showed high resistance at 63°C and moderate resistance at 72°C. However, 80°C for 30min and 90°C for 2min led to complete inactivation of viral particles. In general, the best ethanol concentration tested was 75%, as complete inactivation for most Leuconostoc phages within 30min of incubation was achieved. Peracetic acid, and biocides A, C, E and F were highly effective when used at the same or at a moderately lower concentration as recommended by the producer. Usually, moderate or high concentrations (600-1600ppm) of sodium hypochlorite were necessary to completely inactivate phage particles. Leuconostoc phages were partially inactivated by HPH treatments as remaining viral particles were found even after 8 passes at 100MPa. This is the first report of L. mesenteroides phages isolated from an Argentinean dairy cheese plant. The results of this work could be useful for establishing the most effective physical and chemical treatments for inactivating phages in industrial plants and laboratory environments.
    International journal of food microbiology 02/2014; 177C:81-88. · 3.01 Impact Factor
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    ABSTRACT: The antimicrobial effects of 2 terpenes (citral and linalool) on a Saccharomyces cerevisiae strain isolated from spoiled soft drink have been evaluated, alone or in combination, in relation to pH and aw using in vitro assays. The obtained data were fitted with the logit model to find the growth/no growth boundary regions of the 2 terpenes, focusing the attention on the type of interaction exerted by citral and linalool. In particular, the results showed an increase of citral antimicrobial effect in growth media characterized by low aw value, as well as a higher linalool antimicrobial effect in media at low pH. Moreover, the interactive effects of the 2 terpenes were exploited. The results obtained with the model were validated in an independent experiment. The knowledge of the interactions of essential oil molecules with enhanced antimicrobial activity, in relation to some of the most important chemicophysical variables, can have important industrial applications, since these substances are able to assure the desired antimicrobial effect without negatively modifying the product flavor profile.
    Journal of Food Science 02/2014; · 1.78 Impact Factor
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    ABSTRACT: Nine Leuconostoc mesenteroides phages were isolated during blue cheese manufacture yielding faulty products with reduced eye formation. Their morphologies, restriction profiles, host ranges and long-term survival rates (25 °C, 8 °C, − 20 °C and − 80 °C) were analysed. Based on restriction analysis, six of them were further examined regarding resistance to physical (heat and high pressure homogenization, HPH) and chemical treatments (ethanol, sodium hypochlorite, peracetic acid, biocides A, C, E and F). According to their morphology, L. mesenteroides phages studied in the present work belonged to the Caudovirales order and Siphoviridae family. Six distinct restriction patterns were obtained with EcoRV, HindIII, ClaI and XhoI enzymes, revealing interesting phage diversity in the dairy environment. No significant reductions in phage counts were observed after ten months of storage at –20 °C and − 80 °C, while slightly and moderate decrease in phage numbers were noticed at 8 °C and 25 °C, respectively. The phages subjected to heat treatments generally showed high resistance at 63 °C and moderate resistance at 72 °C. However, 80 °C for 30 min and 90 °C for 2 min led to complete inactivation of viral particles. In general, the best ethanol concentration tested was 75%, as complete inactivation for most Leuconostoc phages within 30 min of incubation was achieved. Peracetic acid, and biocides A, C, E and F were highly effective when used at the same or at a moderately lower concentration as recommended by the producer. Usually, moderate or high concentrations (600–1600 ppm) of sodium hypochlorite were necessary to completely inactivate phage particles. Leuconostoc phages were partially inactivated by HPH treatments as remaining viral particles were found even after 8 passes at 100 MPa. This is the first report of L. mesenteroides phages isolated from an Argentinean dairy cheese plant. The results of this work could be useful for establishing the most effective physical and chemical treatments for inactivating phages in industrial plants and laboratory environments.
    International Journal of Food Microbiology. 01/2014; 177:81–88.
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    ABSTRACT: Salami are typical European dry fermented sausages manufactured mainly with pork meats. Water loss is a crucial aspect of industrial ripening process because it is responsible for the lowering of water activity, which determines limitations to successive conservation. This paper describes two parametric numerical models developed to study the moisture diffusion physics, during ripening and storage in package. Mass transfer equations inside the sausage volume were numerically solved using a finite element technique. A first model describes diffusion phenomena occurring inside the salami and the exchange phenomena involving the surface of the product and the industrial environment, while a second one describes also the evaporation and condensation phenomena occurring between the salami surface and the atmosphere inside the packaging. The models were experimentally validated showing a good agreement with observed data. The numerical models allowed to study the water transfer inside of dry fermented sausages with a detail unreachable by any experimental technique. In addition the models could be used to find the best conditions for ripening, packaging and distribution.
    Journal of Food Engineering. 01/2014; 132:14–20.
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    ABSTRACT: Cultures of Escherichia coli 555 were grown at four levels of carvacrol (0-2mM) and the E. coli endo-metabolome was extracted and measured by (1)H NMR spectroscopy. The results show that glucose concentration is going up with concentration of carvacrol and so do formate until the highest concentration is reached, from which point it suddenly decreases. This is interpreted as if the bacteria are increasingly unable to further metabolize glucose and as if the bacteria increasingly shifts with higher levels of carvacrol toward sugar fermentation as carbon source, until the level of carvacrol reaches a level (2.00mM), where the E. coli must give up. Additionally, the multivariate Principal Component Analysis suggests that the adaptation occurring at sub-lethal doses of carvacrol is different from that occurring at higher doses.
    Food Chemistry 12/2013; 141(4):4367-74. · 3.33 Impact Factor
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    ABSTRACT: The aim was to evaluate the effect of wine addition during manufacturing of dry fermented sausages, in terms of safety aspects (biogenic amine accumulation), aroma profile and sensory characteristics. Three batches of salami were produced: without wine addition and with 7.5% or 15% (v/w) of white wine. The fermented sausages showed characteristics that can increase product diversification. Some of the sensory features (i.e. increased salty perception) can represent an important strategy because of the trend to reduce salt intake for health reasons. The presence of wine immediately reduced the pH and is a source of ethanol, which can have an inhibitory effect against undesirable microflora. The microbiological results observed regarding Enterobacteriaceae and enterococci were encouraging. The addition of wine did not negatively affect the ripening time or increase the presence of biogenic amines. The samples containing wine showed reduced concentrations of putrescine.
    Meat Science 12/2013; 96(3):1395-1402. · 2.75 Impact Factor
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    ABSTRACT: The aim of this work was to assess if a sub-lethal high pressure homogenization (HPH) treatment could modulate in vitro functional and biological properties of probiotic bacteria. Lactobacillus paracasei A13, Lactobacillus acidophilus 08 and Dru, Lactobacillus delbrueckii subsp. lactis 200 and bile-resistant derivatives L. acidophilus Dru+ and L. delbrueckii subsp. lactis 200+ were suspended in phosphate buffered saline solution and treated at 50 MPa. Data obtained showed that HPH can modulate hydrophobicity and auto-aggregation without modification of viability and decarboxylase activity. Resistance to simulated gastric conditions resulted strain-dependent. High resistance was observed for treated L. paracasei A13, L. acidophilus Dru and 08 and L. delbrueckii subsp. lactis 200. The HPH-treatment reduced the resistance to simulated stomach duodenum-passage of L. acidophilus Dru while increased it for L. paracasei A13.Strain viability and resistance to simulated gastric conditions were evaluated treating at 50 MPa cells suspended in acidified buttermilk (pH 4.6) and stored at 4 °C for 30 days. The highest cell viability loss, after 30 d of refrigerated storage, was observed for L. acidophilus Dru, independently of the application of HPH. However, after 30 days of storage, the resistance of L. paracasei A13 to simulated gastric digestion significantly increased in HPH treated cells.
    Lebensmittel-Wissenschaft und-Technologie 10/2013; · 2.55 Impact Factor
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    ABSTRACT: This research investigated the potential of multi-pass homogenization treatment for the inactivation of Salmonella enterica serovar Enteritidis inoculated at different levels in liquid whole egg (LWE) comparing the efficacy of this treatment with a traditional thermal one performed at 65 °C. Moreover, the effects of high pressure treatment (HPH) on structural and functional properties such as viscosity, microstructure and foaming abilities of LWE were investigated. The data obtained suggested that the multi-pass high pressure treatment at 100 MPa of S. enterica serovar Enteritidis inoculated in LWE at 7 and 4 log CFU/ml resulted in a first order inactivation kinetic, while the thermal inactivation curves of S. enterica serovar Enteritidis inoculated at 8 and 4 log CFU/ml presented a non-linear behaviour, with a marked tail after 3 min of treatment at 65 °C. Additionally, HPH treatment caused an increase in foaming capacity of LWE, with respect to the untreated samples, passing from values of 26% of the control to 50% of pressure treated samples.
    Food Microbiology 10/2013; 36(1):63-9. · 3.41 Impact Factor
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    ABSTRACT: High Pressure of Homogenization (HPH) has been proposed to be applied directly to lactic acid bacteria cells at sub-lethal levels in order to enhance some functional properties. Since the principal target of HPH are the cell surface envelope structures, the aim of this work was to study the effect of a HPH, applied at 50 MPa, on cell membrane stress responses of already-known functional strains, isolated from Argentinean products. Specifically, the membrane fatty acid composition of cells before and after the sub-lethal treatment was investigated and the results showed that plasma membranes, their level of unsaturation and their composition are involved in response mechanisms adopted by microbial cells when subjected to a sub-lethal HPH stress. In fact, the data obtained demonstrated that the treatment was able to modify the fatty acid profile of the different strains, although an uniform response was not observed. Further studies are necessary both to elucidate the role of each fatty acid in the cell response mechanisms and to clarify the changes in membrane compositions induced by HPH treatment also in relation to the applicative potential of this technique. This article is protected by copyright. All rights reserved.
    Letters in Applied Microbiology 09/2013; · 1.63 Impact Factor
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    ABSTRACT: Salama da sugo is a fermented sausage from Ferrara tradition, subjected to a long ripening period (4–6 months). It can be consumed after cooking, served with its sugo, i.e. the liquid extracted by cooking process. Besides to pork meat and fat, also NaCl, curing salts, sugar, spices and almost 15% of red wine are added. The aim of this research was the microbial and aromatic profile characterization of Salama da sugo during ripening. The product was sampled in order to study chemico-physical parameters, microbial population composition (Enterobacteriaceae, lactobacilli, enterococci, micrococci and staphylococci, including coagulase positive, fungi, total mesophilic bacteria), biogenic amine content and aromatic profile. The results showed that this traditional product was characterized by a complex aroma.Moreover, the biogenic amine concentration was low (less than 200 mg/kg for tyramine, about 50 mg/kg for cadaverine and putrescine while histamine was below the detection limit).
    Food Control. 08/2013; 32(2):638–643.
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    ABSTRACT: The aim was to evaluate the effects of different water contents (corresponding to aw 0.940, 0.914, 0.895 and 0.875) of sausages at different times on the characteristics of typical Italian dry fermented sausages packaged under two different modified atmospheres (MAP) (100%N2 or 30%CO2/70%N2). During ripening and storage, samples were analyzed to evaluate pH and aw changes, microbial population, biogenic amine (BA) accumulation and aroma profile. The results showed that during storage under MAP several microbiological and enzymatic activities proceeded, leading to changes in aroma profile. In particular, higher hexanal concentrations in samples at lower aw and significant amounts of acetone, 2-butanone, ethanol and 2-butanol in samples at aw>0.900 were detected. Moreover, data showed modifications in BA content, such as higher accumulation in samples at aw>0.900 in MAP with 100%N2. This behavior depends, in first instance, on the aw of the sausages when packaged.
    Meat Science 02/2013; 94(2):177-186. · 2.75 Impact Factor
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    ABSTRACT: High pressure homogenization (HPH) technique is able to significantly reduce spoilage microbiota in fruit juice. On the other hand, aroma compounds and essential oils can have a key role in the microbial stability of these products. For this reason, the aim of this work was to evaluate the combined effects of an aroma compound (citral, used at a concentration of 50mg/l) and HPH treatments (performed at 100MPa for 1-8 successive passes) on the inactivation dynamics of Saccharomyces cerevisiae SPA strain inoculated in apricot juices at level of about 4.5 log CFU/ml. Moreover, growth of surviving yeast cells was measured during the storage of the treated juice at 10°C and pH, water activity, viscosity and volatile molecule profile of apricot juice were studied. Since citral had been diluted in ethanol before the addition to juice, also samples with only ethanol added at the same volume used to dissolve citral were considered. The results showed that yeast cell viability decreased with the increases of passes at 100MPa and the relationship between yeast cell loads and number of passes at 100MPa followed a linear trend. In addition, the effect of HPH treatment can be notably potentiated throughout the presence of citral and ethanol, increasing the time necessary to reach a spoilage threshold during storage. The volatile profiles of the juices added with citral showed a substitution by yeast metabolism of this aldehyde with molecule characterized by a lower antimicrobial activity such as alcohols. The HPH treatments had also a significant effect on pH and viscosity of apricot juices while did not affect a(w).
    International journal of food microbiology 01/2013; 160(3):273-81. · 3.01 Impact Factor
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    ABSTRACT: Low levels of High Pressure of Homogenization (HPH) can be applied directly to lactic acid bacteria cells in order to enhance some functional properties. In a previous work we observed that a 50 MPa HPH treatment increased Lactobacillus paracasei A13 hydrophobicity and resistance to simulated gastric digestion. The aim of this work was to assess the in vivo effects of HPH treatment applied to probiotic lactobacilli on their interaction capacity with the gut and on their ability to induce IgA cell proliferation in mice intestine. BALB/c mice received FITC-labelled cultures of strains, previously treated or not (control) at 50 MPa. Fluorescently labelled cells were studied in the intestine of animals sacrificed 10 and 30 min after intragastric intubation. HPH-treated and control cultures of each strain were orally administered to mice for 2, 5 or 7 consecutive days. The number of IgA-producing cells in the gut was studied by immunohistochemistry. HPH treated probiotic lactobacilli modified their interaction with the small intestine. HPH-treated cells induced a higher IgA response compared to untreated ones, in a strain- and feeding period-dependent way. HPH treatment could increase some in vivo functional characteristics of probiotic strains, highlighting the potential of this technique for the development of probiotic cultures.
    Food Microbiology 12/2012; 32(2):302-7. · 3.41 Impact Factor
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    ABSTRACT: The effect of high pressure homogenization (HPH) with respect to a traditional heat treatment on the inactivation, growth at 8°C after treatments, and volatile profile of adventitious Leuconostoc strains isolated from Cremoso Argentino spoiled cheeses and ingredients used for their manufacture was evaluated. Most Leuconostoc strains revealed elevated resistance to HPH (eight passes, 100 MPa), especially when resuspended in skim milk. Heat treatment was more efficient than HPH in inactivating Leuconostoc cells at the three initial levels tested. The levels of alcohols and sulfur compounds increased during incubation at 8°C in HPH-treated samples, while the highest amounts of aldehydes and ketones characterized were in heated samples. Leuconostoc cells resuspended in skim milk and subjected to one single-pass HPH treatment using an industrial-scale machine showed remarkable reductions in viable cell counts only when 300 and 400 MPa were applied. However, the cell counts of treated samples rose rapidly after only 5 days of storage at 8°C. The Leuconostoc strains tested in this work were highly resistant to the inactivation treatments applied. Neither HPH nor heat treatment assured their total destruction, even though they were more sensitive to the thermal treatment. To enhance the inhibitory effect on Leuconostoc cells, HPH should be combined with a mild heat treatment, which in addition to efficient microbial inactivation, could allow maximal retention of the physicochemical properties of the product.
    Journal of food protection 09/2012; 75(9):1634-41. · 1.83 Impact Factor
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    ABSTRACT: This research was conducted to determine the biogenic amine (BA) and ethyl carbamate (EC) concentrations in commercial Primitivo wine samples and the influence of the use of malolactic starter culture on concentrations of these potentially hazardous compounds in this wine. One hundred sixty bottles of wine from eight producers in the Apulia region of southern Italy were purchased at retail and analyzed. The most common BAs were histamine, 2-phenylethylamine, tyramine, cadaverine, putrescine, spermine, and spermidine. Putrescine (derived from ornithine) was the most abundant BA in all commercial Primitivo wines (5.41 to 9.51 mg/liter), 2-phenylethylamine was detected in only two commercial wines (at less than 2.12 mg/liter), and histamine was found at concentrations of 1.49 to 16.34 mg/liter. The concentration of EC in commercial Primitivo wine was 6.81 to 15.62 ppb, which is not considered dangerous for human health. Malolactic fermentation (MLF) affected the concentrations of BAs and EC differently. For EC, no significant differences were detected between samples of wine produced by spontaneous fermentation and wine that was inoculated malolactic starter. Mean EC concentrations were 12 and 14 ppb in two batches tested (always 18 ppb or less), regardless of whether the malolactic starter was added. Although present at trace levels in wine before the MLF, histamine accumulated during the MLF process, regardless of whether the malolactic starter was added. However, the increase in histamine was higher in wines without the malolactic starter. The concentrations of putrescine and cadaverine increased after MLF, especially in the wine that spontaneously fermented. The use of a selected malolactic starter resulted in reductions in BA concentrations in wine produced by this guided MLF compared with wine produced by spontaneous MLF.
    Journal of food protection 03/2012; 75(3):591-6. · 1.83 Impact Factor
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    ABSTRACT: In this work, two types of traditional Italian dry fermented sausages (Felino-type and Milano-type), were analyzed as a case study. The aim was to evaluate the effect of different environmental conditions in the drying chambers and different starter cultures on the characteristics of the industrially produced sausages. At the end of ripening, the sausages obtained were analyzed to determine microbial counts, biogenic amines (BA) accumulation and volatile aroma profile by using SPME-GC analysis. These profiles were compared with the results of a trained panel group. Felino-type sausages, inoculated only with Staphylococci, were characterized by a slow pH drop and by the presence of higher BA contents. Moreover, specific enzymatic activities of Staphylococci, such as phenylalanine metabolism, were observed and these drastically modified product volatile profiles. Also the different drying conditions applied were able to affect some sensory characteristics of the final products such as hardness and chewiness reflecting different water loss kinetics.
    Food Control 01/2012; Food Control 26 (2012) 416-426. · 2.74 Impact Factor
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    ABSTRACT: Carvacrol, (E)-2-hexenal, and citral at sublethal concentrations combined with isothermal heating between 55 and 68°C were assessed for their effects on Listeria monocytogenes 56LY. Experimental survival curves were obtained and fitted to the Weibull equation to estimate parameters describing their shape and rate. These parameters were further used to assess the impact of this combination of treatments on the cell resistance distribution during inactivation. The sublethal concentrations of the aroma compounds used (i.e., 50 mg/liter citral, 65 mg/liter (E)-2-hexenal, and 30 mg/liter carvacrol) did not prevent the growth of L. monocytogenes at 37°C but did enhance inactivation. Between 55 and 63°C, the presence of the aroma compounds reduced by about two-thirds the time needed for a 5-log reduction of the microbial counts, e.g., from 145.75 h in the control treatment (at 55°C) to 40.84 h in the presence of carvacrol (at the same temperature). The mean and variance observed in the frequency distribution of resistance were reduced as the temperature increased. The results obtained at isothermal temperatures and with single aroma components provide basic information regarding components frequently found in essential oils, which can be used in combination with less extreme thermal treatments to provide energy conservation and improve food quality.
    Journal of food protection 12/2011; 74(12):2070-8. · 1.83 Impact Factor

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