Pietro Damiani

ANTIMOULD ACTIVITY OF SOURDOUGH LACTIC ACID BACTERIA: IDENTIFICATION OF A MIXTURE OF ORGANIC ACIDS PRODUCED BY LACTOBACILLUS SANFRANCISCO CB1

Abstract Sourdough lactic acid bacteria, cultivated in wheat flour hydrolysate, produced antimould compounds. The antimould activity varied greatly among the strains and was mainly detected within obligately heterofermentative Lactobacillus spp. Among these, Lb. sanfrancisco CB1 had the largest spectrum. It inhibited moulds related to bread spoilage such as Fusarium, Penicillium, Aspergillus and Monilia. A mixture of acetic, caproic, formic, propionic, butyric and n-valeric acids, acting in a synergistic way, was responsible for the antimould activity. Caproic acid played a key role in inhibiting mould growth.

Volatile compound and organic acid productions by mixed wheat sour dough starters: influence of fermentation parameters and dynamics during baking

Lactobacillus brevis subsp. lindneri CB1, Lactobacillus plantarum DC400 and Saccharomyces cerevisiae 141 or Saccharomyces exiguus M14 were used as starters to produce wheat sour dough breads. Sour doughs with higher relative percentage of yeast fermentation products (1-propanol, 2-methyl-1-propanol, 3-methyl-1-butanol and ethanol) and with higher total peak area of volatile compounds, or with a more complete profile (higher amounts of ethylacetate and lactic and acetic acids, and the presence of carbonyl compounds) were produced by the associations between lactic acid bacteria (LAB) and S. cerevisiae 141 or S. exiguus M14, respectively. Low temperature (25°C) and sour dough firmness (dough yield 135) were appropriate for LAB souring activities but limited yeast metabolism. Raising the temperature to 30°C and semi-fluid sour doughs gave more complete volatile profiles. Flour ash content from 0·55–1% positively influenced the total amount of volatiles and lactic and acetic acid productions. While at 3 h the sour dough was mainly characterized by iso-alcohols, an increase of leavening time up to 9 h gave a total amount of volatiles about three times higher than that at 5 h and strengthened the LAB contribution. The additions of fructose and citrate to the dough enhanced the acetic acid and volatile synthesis by LAB, respectively. After baking, the ethanol disappeared, 2-methyl-1-propanal was synthetized, lactic and acetic acids remained constant, the total amount of volatiles was reduced to a level

Analysis of fumonisins B1, B2 and B3 in corn-based baby food by pressurized liquid extraction and liquid chromatography/tandem mass spectrometry

A sensitive and reliable method using pressurized liquid extraction (PLE) and liquid chromatography (LC)/electrospray ionization (ESI) tandem mass spectrometry with a triple quadrupole (QqQ) analyzer has been developed for the analysis of fumonisin B(1) (FB(1)), fumonisin B(2) (FB(2)) and fumonisin B(3) (FB(3)) in corn-based baby foods. Influence of several extraction parameters that affect PLE efficiency such as temperature, pressure, solvent extraction, number of cycles and dispersant/clean-up agents were studied. The selected PLE operating method was: 3g of sample was packed into 11 ml stainless-steel cell and fumonisins were extracted with methanol at 40 degrees C, 34 atm in one cycle of 5 min at 60% flush. The analytes were ionized in ESI operating with positive ion mode and identified by selecting two monitoring transitions, permitting quantification and confirmation in a single injection. Recoveries ranged from 68% to 83% at fortification levels of 200 microg kg(-1) with relative standard deviation (RSD) from 4% to 12%. The limits of quantification were from 2 microg kg(-1) for FB(1) and FB(2), and 5 microg kg(-1) for FB(3), which are below the maximum residue level established by the European Union legislation in infant formulas. The proposed method was successfully applied to the analysis of twenty seven samples of baby food products collected from different markets, and one positive sample with a content of 15.9 microg kg(-1) for FB(1), 9.2 microg kg(-1)for FB(2) and 5.8 microg kg(-1) for FB(3) was obtained. Given the simplicity and potential of the proposed procedure, its application for safety control is recommended.

Survey of fumonisins B1, B2 and B3 in conventional and organic retail corn products in Spain and Italy and estimated dietary exposure

A survey was conducted to determine the occurrence of fumonisin B1, B2 and B3 during 2007 in 186 samples of organic and conventional locally available corn products. Samples included baby food (n = 62), corn flour (11), cornflakes (23), pasta (14), cookies (17) and other corn products (59) were obtained from popular markets of Valencia (Spain) and Perugia (Italy). The analytical method used pressurized liquid extraction and liquid chromatography/electrospray ionization tandem mass spectrometry with a triple quadrupole (QqQ) analyser. Of the 104 Spanish samples, 22% contained levels in the range of 2–449 µg kg−1, 2–229 µg kg−1 and 6–105 µg kg−1 for FB1, FB2 and FB3, respectively, while 19 (23%) of the 82 Italian samples were positive with quantifiable levels between 2–235 µg kg−1, 3–187 µg kg−1, and 4–40 µg kg−1 for fumonisins B1, B2 and B3, respectively. Overall, none of the Italian samples and only one organic baby food sample from a Spanish market was above the maximum permitted levels established by European legislation. Fumonisins were found mostly in corn flour followed by cookies and cornflakes. Eleven samples from Spain and nine samples from Italy were organic products, being contaminated the 72% and 77% of the samples, respectively. Analysis of the results showed that levels of fumonisins in corn products were similar in Italy and Spain. The safety of fumonisin intake through corn products was demonstrated by the calculation of the estimated daily intake of both populations considering organic and conventional products separately, which ranged from 1.7 × 10−3 to 0.72 µg kg−1 bw day−1 and comparing them with the provisional maximum total daily intake (PMTDI) of 2 µg kg−1 bw day−1 established by the European Union.

Stereospecific analysis of the triacylglycerol fraction and linear discriminant analysis in a climatic differentiation of umbrian extra-virgin olive oils

Abstract Stereospecific analysis of the triacylglycerol fraction is an important tool for the characterisation of extra-virgin olive oils. The composition in the sn-1, sn-2 and sn-3 positions of triacylglycerols of extra-virgin olive oils produced in years 1992–1994 in areas characterised by increasing environmental severity (groups 1 and 2, respectively) is considered. This analytical method is based on chromatographic techniques, coupled with enzymatic ones. Linear discriminant analysis (LDA) has been applied successively for the differentiation and classification of the two groups for each year according to the positional distribution of fatty acids (palmitic, palmitoleic, stearic, oleic and linoleic acids) in the glycerol backbone. Even though the data were not very numerous, LDA has allowed a partial or total separation of scores along the discriminant eigenvector according to the climatic groups.

Determination of sorbic acid in margarine and butter by high-performance liquid chromatography with fluorescence detection

A procedure is reported for the separation and determination of sorbic acid, as a derivative of 4-bromoethyl-6,7-dimethoxycoumarin, by reversed-phase high-performance liquid chromatography with fluorescence detection using enanthic acid as an internal standard. Sorbic acid, separated from samples of commercial margarine and butter by steam distillation, was evaluated using the proposed procedure and by UV absorption and visible spectrophotometric methods (AOAC). The preparation of the calibration graph and the determination of sorbic acid with the visible spectrophotometric method was improved. The sorbic acid content determined using UV and visible spectrophotometric methods was higher than that obtained with the reversed-phase performance liquid chromatographic method owing to the presence of interfering substances in the samples. The range of recovery and the precision of the proposed method and the reference methods are also reported.

Stereospecific analysis of triacylglycerol and phospholipid fractions of four freshwater fish species: Salmo trutta, Ictalurus punctatus, Ictalurus melas and Micropterus salmoides.

The fatty acid compositions and the positional distributions of fatty acid in triacylglycerol (TAGs) and phospholipid (PLs) fractions of four cultured freshwater fish species (Salmo trutta, Ictalurus punctatus, Ictalurus melas and Micropterus salmoides) were investigated. As regards the TAGs fraction, the S. trutta (trout) and I. punctatus (channel catfish) species had the highest % content in n3 polyunsaturated fatty acids (PUFAs) and the lowest n6/n3 ratio; this ratio resulted always lower than 1 in all the considered fish species. The PLs fraction of the considered fish was very interesting because of the high percentage of PUFAs, both in phosphatidylcholines and in phosphatidylethanolamines. The fatty acid distribution among the three sn-positions of the glycerol backbone was non-random; generally, both n6 and n3 PUFAs were mainly distributed between sn-2- and sn-3-positions of TAGs while the contents in sn-1-position were generally lower; in PLs fraction these fatty acids preferred the sn-2-position.

The sourdough microflora Microbiological, biochemical and breadmaking characteristics of doughs fermented with freeze-dried mixed starters, freeze-dried wheat sourdough and mixed fresh-cell starters

Freeze-dried mixed starters, freeze-dried wheat sourdough and mixed fresh-cell starters made withLactobacillus sanfrancisco CBI,L. plantarum DC400 andSaccharomyces cerevisiae 141 and/orS. exiguus M14 were used for leavening wheat doughs, and their microbiological, biochemical and breadmaking characteristics were compared with those of Italian traditional doughs produced by bakers yeast. All the doughs fermented with starters had more balanced microbiological and biochemical characteristics than dough started with bakers yeast in which alcoholic fermentation end-products largely predominated. By using starters, the greatest lactic acid bacteria cell number and acetic acid production, were achieved, along with more complete profiles of volatile compounds and greater structural stability of fermented doughs. Fresh-cell starters showed higher microbial functionality and represented the only way to enrich the doughs withS. exiguus M14, some of which survived the freeze-drying process. No differences were detected between the two different types of freeze-dried starters and the subsequent use (10 times) of doughs initially produced with freezedried starters eliminated initial differences in the microbial functionality with respect to fresh-cell starters.

Detection of cow milk in donkey milk by chemometric procedures on triacylglycerol stereospecific analysis results

Stereospecific analysis is an important tool for the characterization of lipid fraction of food matrices, and also of milk samples. The results of a chemical-enzymatic-chromatographic analytical method were elaborated by chemometric procedures such as linear discriminant analysis (LDA) and artificial neural network (ANN). According to the total composition and intrapositional fatty acid distribution in the triacylglycerol (TAG) backbone, the obtained results were able to characterize pure milk samples and milk mixtures with 1, 3, 5% cow milk added to donkey milk. The resulting score was very satisfactory. Totally correct classified samples were obtained when the TAG stereospecific results of all the considered milk mixtures (donkey-cow) were elaborated by LDA and ANN chemometric procedures.

Triacylglycerol stereospecific analysis and linear discriminant analysis for milk speciation

Product authenticity is an important topic in dairy sector. Dairy products sold for public consumption must be accurately labelled in accordance with the contained milk species. Linear discriminant analysis (LDA), a common chemometric procedure, has been applied to fatty acid% composition to classify pure milk samples (cow, ewe, buffalo, donkey, goat). All original grouped cases were correctly classified, while 90% of cross-validated grouped cases were correctly classified. Another objective of this research was the characterisation of cow-ewe milk mixtures in order to reveal a common fraud in dairy field, that is the addition of cow to ewe milk. Stereospecific analysis of triacylglycerols (TAG), a method based on chemical-enzymatic procedures coupled with chromatographic techniques, has been carried out to detect fraudulent milk additions, in particular 1, 3, 5% cow milk added to ewe milk. When only TAG composition data were used for the elaboration, 75% of original grouped cases were correctly classified, while totally correct classified samples were obtained when both total and intrapositional TAG data were used. Also the results of cross validation were better when TAG stereospecific analysis data were considered as LDA variables. In particular, 100% of cross-validated grouped cases were obtained when 5% cow milk mixtures were considered.