Rind Samples Research Articles

Evaluation of drying and extraction parameters for the extraction yield of watermelon (Citrullus lanatus (Thunb.)) rind using statistical design experiment

Watermelon rind contributes about 30% of overall watermelon mass and is considered the most underutilized resource as it is usually discarded as waste. Watermelon rind resources have great potential economic value in various industries. Thus, utilizing the rind could decrease the amount of biological waste in the environment. Therefore, this study aims to determine the optimal conditions in extracting oven and dehydrator drying watermelon rind using a sonicator extraction procedure. Watermelon rind samples were evaluated using a one-factor-at-a-time (OFAT) evaluation to identify the most significant factor for the sonicator extraction time (0.5-3 hrs), ethanol concentration (20-100%), solvent-tosolid ratio (10:1-50:1 v/w), and sample drying time (24-48 hrs) parameters. The highest yield obtained for the oven drying sample was at one hr extraction time (15%), 100% ethanol concentration (12.5%), 30:1 v/w ratio (12%), and 48 hrs drying (9%). Meanwhile, the extraction yield of dehydrator drying sample was optimized at one hr of extraction time with 10% yield 100% of ethanol concentration with 15.4% yield, 40:1 v/w of solvent ratio with 14.7% yield, and 48 hrs of drying with 8% yield. The optimum extract yield of dehydrator drying sample could be further applied for cosmeceutical application as it produced higher yield compared to oven drying sample.

Breeding of Persian melon: Purpose to increase volatile compounds in melon (Cucumis melo) intergroup F1 cross population

AbstractUnderstanding the volatile profile of melon is an ever increasingly important task for breeders for enhancing their flavour component. For this purpose, F1 progeny and parental lines were analysed using headspace‐solid phase microextraction gas chromatography–mass spectrometry‐based analysis. Diallel analysis showed that most of the investigated compounds were controlled via non‐additive genetic effects with general combining ability to specific combining ability ratios of less than 0.4. High heterosis results were observed in alcohols such as ethanol and octanol in both rind and mesocarp samples and benzylalcohol in the rind. It was also noted that the ester‐based compounds with high heterosis values in mesocarp samples differed from those with heterosis in rind samples. These observations further emphasize the non‐additive control of these compounds. It can be concluded that non‐additive genetic control is strongly governing the genetic profile within the studied progeny. This finding indicated that dudaim lines as a valuable genetic material enhanced the volatile profile of odourless commercial types of ameri and inodorus melon.

Quantitative PCR reveals the frequency and distribution of 3 indigenous yeast species across a range of specialty cheeses.

Indigenous microorganisms are important components of the complex ecosystem of many dairy foods including cheeses, and they are potential contributors to the development of a specific cheese's sensory properties. Among these indigenous microorganisms are the yeasts Cyberlindnera jadinii, Pichia kudriavzevii, and Kazachstania servazzii, which were previously detected using traditional microbiological methods in both raw milk and some artisanal specialty cheeses produced in the province of Québec, Canada. However, their levels across different cheese varieties are unknown. A highly specific and sensitive real-time quantitative PCR assay was developed to quantitate these yeast species in a variety of specialty cheeses (bloomy-rind, washed-rind, and natural-rind cheeses from raw, thermized, and pasteurized milks). The specificity of the quantitative PCR assay was validated, and it showed no cross-amplification with 11 other fungal microorganisms usually found in bloomy-rind and washed-rind cheeses. Cyberlindnera jadinii and P. kudriavzevii were found in the majority of the cheeses analyzed (25 of 29 and 24 of 29 cheeses, respectively) in concentrations up to 104 to 108 gene copies/g in the cheese cores, which are considered oxygen-poor environments, and 101 to 104 gene copies/cm2 in the rind. However, their high abundance was not observed in the same samples. Whereas C. jadinii was present and dominant in all core and rind samples, P. kudriavzevii was mostly present in cheese cores. In contrast, K. servazzii was present in the rinds of only 2 cheeses, in concentrations ranging from 101 to 103 gene copies/cm2, and in 1 cheese core at 105 gene copies/g. Thus, in the ecosystems of specialty cheeses, indigenous yeasts are highly frequent but variable, with certain species selectively present in specific varieties. These results shed light on some indigenous yeasts that establish during the ripening of specialty cheeses.

Effect of Multi-function Disintegrator Grinding on the Particle Size of Garcinia indica and Garcinia cambogia Rind Powder

Ultra-fine formulations edible dried fruit rind material provides a vast range of opportunities for the development of new products and applications in the food systems. The Garcinia indica and Garcinia cambogia, both species have a range of uses from culinary to healthcare applications. The dried rind of both species was attempted to study size and proportion of ultra-fine powder formed using Multi-function disintegrator as a function of different durations of grinding. The particle size and relative proportions were assessed using Zetasizer dynamic light scattering apparatus. A set of three major peaks in each sample was analyzed for particle size and intensity. In G. indica the result in peak1 for size and intensity, the minimum size of particle recorded was 175.8 nm from the sample ground 60 minutes. In G. cambogia minimum particle size recorded was 461.01nm from the sample ground for 60 minutes. The different particle sizes ranging from 48.13 nm to 3705.63 nm was recorded in powder resulting from different durations of grinding at full speed of the disintegrator. The results suggested that samples ground for longer duration in a simple particle disintegrator could accumulate ultra-fine particles in both G. indica and G. cambogia rind samples.

Plant-based antimicrobials inactivate Listeria monocytogenes and Salmonella enterica on melons grown in different regions of the United States

The efficacy of plant-based antimicrobials against Salmonella Newport and Listeria monocytogenes on melon rinds was evaluated. Four cantaloupe and 3 honeydew melon varieties grown in Georgia, Arizona, Texas, North Carolina, Indiana and California were tested. Melon rinds (10 g pieces) were inoculated with 5–6 log CFU/10 g rind of S. Newport or L. monocytogenes. Samples were then immersed in 5 % olive extract or 0.5 % oregano oil antimicrobial solution and gently agitated for 2 min. Samples were stored at 4 °C and surviving populations of both bacteria were enumerated at days 0 and 3. Plant-based antimicrobials reduced S. Newport and L.monocytogenes population on all rind samples, regardless of the melon types, varieties or growing locations. Compared to the control, antimicrobial treatments caused up to 3.6 and 4.0 log reductions in populations of Salmonella and L. monocytogenes, respectively. In most cases, plant-based antimicrobial treatments reduced pathogen populations to below the detection limit (1 log CFU/g) at day 3. In general, oregano oil had better antimicrobial activity than olive extract and the antimicrobial treatments were more effective on Salmonella than on L. monocytogenes. The plant-based antimicrobial treatments exhibited better microbial reductions on honeydews than on cantaloupes. These antimicrobials could potentially be used as sanitizers for decontaminating melons.

Uji Aktivitas Antibakteri Sediaan Gel Hand Sanitizer Ekstrak Kulit Buah Jengkol (Archidendron pauciflorum (Benth.) Nielsen) terhadap Bakteri Escherichia coli

Escherichia coli is a bacteria that can cause diarrhea. The emergence of diarrhea is caused by a lack of public awareness in maintaining cleanliness, including hand hygiene. Along with the times, people prefer to use hand sanitizers that are more practical, easy to carry, and easy to use. However, most hand sanitizer preparations contain alcohol which has the potential to cause dryness and irritation if used continuously. Therefore, jengkol rind is used which contains flavonoid compounds, saponins, tannins, and anthraquinones which have antibacterial properties against Escherichia coli. The purpose of this study was to determine the antibacterial activity of the hand sanitizer gel of jengkol fruit peel extract against Escherichia coli using the disc diffusion method. The research method used was experimental. The jengkol rind samples were extracted using the maceration method with 70% ethanol. The positive control used was a hand sanitizer with chloroxylenol content and the negative control was a gel base without extract. Jengkol rind extract is made into preparations in concentrations of 5%, 10%, and 15%. The preparation was tested for physical stability for 28 days including organoleptic, pH, homogeneity, dispersibility, adhesion, protective power, and drying time. The results showed that the preparations with a concentration of 5%, 10%, and 15% jengkol fruit peel extract had an average inhibition zone of 7.00 ± 0.8165 mm, 13.00 ± 0.8165 mm, and 17.25 ± 0.95743 mm. Of the three formulations, the formulation with a concentration of 10% is the most effective concentration because a small concentration already has a strong inhibitory power category. The hand sanitizer gel of jengkol fruit peel extract fulfills the requirements for organoleptic tests, homogeneity, pH, spreadability, adhesion, and protection power and is stable in the 28-day storage period, but does not meet the requirements for drying time.

Temporal differences in microbial composition of Époisses cheese rinds during ripening and storage

Époisses is a protected designation of origin smear-ripened cheese from the Burgundy region in France. It has an orange color and a strong flavor, both of which are generated by surface microorganisms. The objective of the present study was to investigate the microbial dynamics at the surface of Époisses cheese during ripening and postmanufacturing storage at low temperatures. Rind samples were analyzed by enumeration on agar plates and by 16S rRNA gene and internal transcribed spacer amplicon sequencing. During most of the ripening process, the counts of yeasts, which corresponded to the species Debaryomyces hansenii and Geotrichum candidum, were higher than those of the aerobic acid-sensitive bacteria. Debaryomyces hansenii reached a level of about 3 × 108 cfu/cm2, and its viability strongly decreased in the late stage of ripening and during storage at 4°C. Two of the inoculated bacterial species, Brevibacterium aurantiacum and Staphylococcus xylosus, did not establish themselves at the cheese surface. At the end of ripening, among the 18 most abundant bacterial species detected by amplicon sequencing, 14 were gram-negative, mainly from genera Psychrobacter, Vibrio, Halomonas, and Mesonia. It was hypothesized that the high moisture level of the Époisses rinds, due the humid atmosphere of the ripening rooms and to the frequent washings of the curds, favored growth of these gram-negative species. These species may be of interest for the development of efficient ripening cultures. In addition, because the orange color of Époisses cheeses could not be attributed to the growth of Brevibacterium, it would be interesting to investigate the type and origin of the pigments that confer color to this cheese.

The Moroccan Pomegranate: An Underrated Source of Tannins Extracts and Natural Antimicrobials from Juice Processing Byproducts

Purpose The pomegranate juice manufacturing industry produces vast quantities of non-edible portions of fruit as a by-product. The rind is a good source of many beneficial functional components, especially polyphenols and in particular tannins. This research was undertaken to expose the presence of active substances, including tannin compounds, in the crude extracts (aqueous (AE) and methanolic (ME)) and their fractions increasing in polarity, from Moroccan pomegranate rind samples. Methods To describe the molecular distribution of tannin content in crude extracts, steric exclusion chromatography (SEC) on Sephadex gel 50 was carried out. In addition, their antimicrobial properties were tested using agar diffusion, dispersion, and microdilution methods against the bacterial strains Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and the yeast strains Saccharomyces cerevisiae and Candida tropicalis. Results For both crude extracts, the SEC showed qualitative and quantitative differences in tannin polymerization. Diameters of inhibition zones (DIZ) obtained against bacterial species ranged from 20.6 to 30.3 mm for ME, from 10.8 to 15.3 mm for AE and from 0 to 16.6 mm for fractions. Among the selected fungal cultures, the highest antifungal activity was reported against S. cerevisiae; with an inhibition rate (I %) ranging up to 99.00% for AE. With I % reaching up to 93.35%, the C. tropicalis strain was more sensitive to ME, although the AE has no inhibitory effect on this yeast. For fractions, the I % ranged from 7.03 to 98.03% where a synergistic antifungal effect was observed between fractions. Conclusion Pomegranate processing by-product is a potential source which could be used as natural preservatives in food industry and non-toxic matrices replacing hazardous materials in surface treatment.

Consumer acceptance of watermelon flesh-rind blends and the effect of rind on refreshing perception.

Watermelon flesh is widely consumed for its appealing flavor and refreshing properties, though the rind of the fruit also has traits of interest, especially its nutritional benefits. This study aimed to determine if watermelon flesh blended with 0%, 10%, 20%, and 30% w/w rind could appeal to consumers, and the effect of rind on the refreshing perception was investigated. Consumers (n = 102) evaluated the liking and intensity levels of overall flavor, sweet, sour, green, watermelon flavor, and refreshing quality along with questions regarding the texture, off flavors, and aftertaste of the samples. The addition of rind was acceptable up to the 20% rind level, which was given an overall rating above the midpoint of the scale, while the 10% and 0% rind samples did not differ significantly (P < 0.001). Overall liking most strongly correlated with sweet liking (r = 0.78, P < 0.001) and watermelon flavor liking (r = 0.77, P < 0.001). Refreshing liking most strongly correlated with watermelon flavor liking (r = 0.75, P < 0.001) and decreased with addition of rind in the samples (P < 0.001). The excessive green notes, off flavors, and undesirable texture of rind decreased the hedonic and refreshing ratings of samples with 20% and 30% rind, respectively. This research demonstrated the acceptability of using up to 20% rind to supplement watermelon juice blends and results suggested that watermelon flavor drives the refreshing perception. PRACTICAL APPLICATION: These findings exhibit the diversity in consumer preferences for watermelon flesh blended with rind using a consumer test. The refreshing properties of watermelon flesh as related to sweetness and watermelon flavor, along with the flavor and mouthfeel attributes contributed by watermelon rind, are highlighted. Manufacturers of fruit-based beverages can apply this research to inform development of refreshing products, watermelon flavored products, or products that utilize rind waste.

Endogenous microbial contamination of melons (Cucumis melo) from international trade: an underestimated risk for the consumer?

Fruits and vegetables have increasingly been related to foodborne outbreaks. Besides surface contamination, a possible internalization of microorganisms into edible parts of plants during growth has already been observed. To examine an actual risk for the consumer, microbial contamination of the rind and pulp of 147 muskmelons from international trade was assessed using cultural and biochemical methods, polymerase chain reaction and matrix-assisted laser desorption/ionization-time of flight mass spectrometry. One hundred percent of the rind samples [3.69-8.92 log colony forming units (CFU) g-1 ] and 89.8% of the pulp samples (maximum load 3.66 log CFU g-1 ) were microbiologically contaminated. Among the 432 pulp isolates, opportunistic and potentially pathogenic bacteria were identified, mainly Staphylococcus spp. (48.9%), Clostridium spp. (42.9%) and Enterobacteriaceae (27.9%). Salmonella spp., Escherichia coli and isolates of the Bacillus cereus group were found on the rind (1.4%, 0.7% and 42.9%, respectively) and in the pulp (0.7%, 1.4% and 4.7%). Clostridium perfringens was isolated from the rind of seven melons. The present study revealed a regularly occurring internal contamination of melons. Possible health risks for consumers because of an occurrence of microorganisms in melon pulp should be considered in future food safety assessments. © 2018 Society of Chemical Industry.

Abundance and potential contribution of Gram-negative cheese rind bacteria from Austrian artisanal hard cheeses

Many different Gram-negative bacteria have been shown to be present on cheese rinds. Their contribution to cheese ripening is however, only partially understood until now. Here, cheese rind samples were taken from Vorarlberger Bergkäse (VB), an artisanal hard washed-rind cheese from Austria. Ripening cellars of two cheese production facilities in Austria were sampled at the day of production and after 14, 30, 90 and 160days of ripening. To obtain insights into the possible contribution of Advenella, Psychrobacter, and Psychroflexus to cheese ripening, we sequenced and analyzed the genomes of one strain of each genus isolated from VB cheese rinds. Additionally, quantitative PCRs (qPCRs) were performed to follow the abundance of Advenella, Psychrobacter, and Psychroflexus on VB rinds during ripening in both facilities. qPCR results showed that Psychrobacter was most abundant on cheese rinds and the abundance of Advenella decreased throughout the first month of ripening and increased significantly after 30days of ripening (p<0.01). Psychrobacter and Psychroflexus increased significantly during the first 30 ripening days (p<0.01), and decreased to their initial abundance during the rest of the ripening time (p<0.05). Genome sequencing resulted in 17 to 27 contigs with assembly sizes of 2.7 Mbp for Psychroflexus, 3 Mbp for Psychrobacter, and 4.3 Mbp for Advenella. Our results reveal that each genome harbors enzymes shown to be important for cheese ripening in other bacteria such as: Cystathionine/Methionine beta or gamma-lyases, many proteases and peptidases (including proline iminopeptidases), aminotransferases, and lipases. Thus, all three isolates have the potential to contribute positively to cheese ripening. In conclusion, the three species quantified were stable community members throughout the ripening process and their abundance on cheese rinds together with the results from genome sequencing suggest an important contribution of these bacteria to cheese ripening.

Biofilm of Escherichia coli O157:H7 on cantaloupe surface is resistant to lauroyl arginate ethyl and sodium hypochlorite

Biofilms formed by Escherichia coli O157:H7 on cantaloupe rind were characterized in this study. Cantaloupe rind pieces inoculated with E. coli O157:H7 B6-914 was sampled after 2, 12, and 24h incubation for imaging with cryo-scanning electron microscopy (Cryo-SEM) or treating with lauroyl arginate ethyl (LAE) or sodium hypochlorite (SHC). Cryo-SEM images showed that E. coli O157:H7 formed a biofilm within 12h on the rind surface. For rind samples treated with LAE or SHC, the residual cell counts were significantly different (p<0.05) between 2 and 12h incubation, and between 2 and 24h of incubation. For the 2h incubation samples, E. coli O157:H7 was undetectable (>5-log reduction) after treatment with 2000μg/mL of LAE or SHC. In contrast, for 12h incubation samples, 2000μg/mL of LAE or SHC could only achieve 1.74 or 1.86-log reduction, respectively. The study showed the low efficacy of LAE and SHC on cantaloupe rind surface to reduce the E. coli biofilm, suggesting the needs for cantaloupe cleaning methods beyond washing with conventional antimicrobial agents.

The origin of felsic microgranitoid enclaves: Insights from plagioclase crystal size distributions and thermodynamic models

Magma mixing is widely recognized in contemporary petrology as one of the primary igneous processes. Microgranitoid enclaves (MEs) are considered to be remnants of such mixing processes, and the term has a well-established genetic implication. However, microgranitoid enclaves span a wide range of compositions, and felsic varieties are also frequently reported.Nd–Sr isotope and textural data from felsic microgranitoid enclaves (FMEs), mafic microgranitoid enclaves (MMEs) and host granites from the Salto pluton, Itu Granitic Province, show that the cm-sized MMEs are dioritic, have medium-grained igneous textures and xenocrysts of alkali feldspar and quartz. The FMEs are cm- to meter-sized, have spheric shapes, show corrugated contacts with the host granites, and have resorbed feldspars and deformed quartz crystals interpreted as xenocrysts set in a fine-grained groundmass.Compared to the host granites, both MME and FME samples have increased FeO, MgO, TiO2, P2O5 and Zr contents, but their Sr and Nd isotope signatures are identical: FME 87Sr/86Sri=0.7088–0.7063, εNdi=−10.0 to −10.2; MME 87Sr/86Sri=0.7070, εNdi=−10.5; host granite 87Sr/86Sri 0.7056–0.7060, εNdi=−10.2 to −10.3. These indicate that the enclaves derive from a similar source, although the melts from which they formed were probably hotter and chemically more primitive than their host granites.Crystal size distributions (CSDs) of plagioclase in samples drilled from rinds and cores of three FMEs show that the rind samples are systematically finer-grained than the samples from the cores, which indicates that the FMEs cooled inwards and contradict interpretations that the FMEs are autoliths. Thermal modeling suggests that a slightly more primitive, hotter magma would be thermally equilibrated with an evolved resident melt within weeks after mixing/mingling. Upon thermal equilibrium, the FMEs would have an increased crystal cargo, and the resulting touching framework would impart a solid-like behavior to the FME-forming magma, which would lead to a contrast in rheology, fragmentation, dragging and preservation of felsic replenishment batches as distinct enclaves.

Cultivation-independent analysis of microbial communities on Austrian raw milk hard cheese rinds

“Vorarlberger Bergkäse” (VB) is an Austrian artisanal hard cheese produced from raw cow's milk. The composition of its rind microbiota and the changes in the microbial communities during ripening have not previously been investigated. This study used 16S and 18S rRNA gene cloning and sequencing to characterize the bacterial and fungal communities of seven pooled cheese rind samples taken in seven different ripening cellars of three Austrian dairy facilities. A total of 408 clones for 16S and 322 clones for 18S rRNA gene libraries were used for taxonomic classification, revealing 39 bacterial and seven fungal operational taxonomic units (OTUs). Bacterial OTUs belonged to four different phyla. Most OTUs were affiliated to genera often found in cheese, including high numbers of coryneforms. The most abundant OTU from 16S rRNA gene libraries showed highest similarity to Halomonas. Young cheese rinds were dominated by Actinobacteria or Proteobacteria, particularly by Halomonas and Brevibacterium aurantiacum, while Staphyloccocus equorum was most abundant in old cheeses. The most abundant 18S rRNA OTU had highest similarity to the filamentous fungus Scopulariopsis brevicaulis. Pairwise correlation analyses revealed putative co-occurrences between a number of OTUs. It was possible to discriminate the different cheese rind microbiota at the community-level by facility affiliation and ripening time. This work provides insights into the microbial composition of VB cheese rinds and might allow the processing- and ripening conditions to be improved to enhance the quality of the product.

Behaviour of Escherichia coli strains during semi-hard and hard raw milk cheese production

The behaviour of two Escherichia coli strains, one with a high and the other with a low thermotolerance phenotype, was investigated during production and ripening of Swiss semi-hard and hard raw milk cheese. In semi-hard cheese, counts of E. coli increased during production, before a log-linear decrease occurred during ripening, with a faster rate of reduction in core than in rind samples, and faster reduction of the more heat-sensitive strain in rind samples. Nevertheless, at the end of semi-hard cheese ripening, E. coli were present at least at 1.3 log10 cfu g−1 in rind samples and remained detectable by enrichment of core samples. During the first day of hard cheese production, both E. coli strains were almost completely inactivated. Detection by enrichment was possible in one of twelve spiked cheeses after 16 weeks, indicating the potential of a thermotolerant E. coli strain to survive until the end of ripening.

Topochemical distribution of lignin and hydroxycinnamic acids in sugar-cane cell walls and its correlation with the enzymatic hydrolysis of polysaccharides

BackgroundLignin and hemicelluloses are the major components limiting enzyme infiltration into cell walls. Determination of the topochemical distribution of lignin and aromatics in sugar cane might provide important data on the recalcitrance of specific cells. We used cellular ultraviolet (UV) microspectrophotometry (UMSP) to topochemically detect lignin and hydroxycinnamic acids in individual fiber, vessel and parenchyma cell walls of untreated and chlorite-treated sugar cane. Internodes, presenting typical vascular bundles and sucrose-storing parenchyma cells, were divided into rind and pith fractions.ResultsVascular bundles were more abundant in the rind, whereas parenchyma cells predominated in the pith region. UV measurements of untreated fiber cell walls gave absorbance spectra typical of grass lignin, with a band at 278 nm and a pronounced shoulder at 315 nm, assigned to the presence of hydroxycinnamic acids linked to lignin and/or to arabino-methylglucurono-xylans. The cell walls of vessels had the highest level of lignification, followed by those of fibers and parenchyma. Pith parenchyma cell walls were characterized by very low absorbance values at 278 nm; however, a distinct peak at 315 nm indicated that pith parenchyma cells are not extensively lignified, but contain significant amounts of hydroxycinnamic acids. Cellular UV image profiles scanned with an absorbance intensity maximum of 278 nm identified the pattern of lignin distribution in the individual cell walls, with the highest concentration occurring in the middle lamella and cell corners. Chlorite treatment caused a rapid removal of hydroxycinnamic acids from parenchyma cell walls, whereas the thicker fiber cell walls were delignified only after a long treatment duration (4 hours). Untreated pith samples were promptly hydrolyzed by cellulases, reaching 63% of cellulose conversion after 72 hours of hydrolysis, whereas untreated rind samples achieved only 20% hydrolyzation.ConclusionThe low recalcitrance of pith cells correlated with the low UV-absorbance values seen in parenchyma cells. Chlorite treatment of pith cells did not enhance cellulose conversion. By contrast, application of the same treatment to rind cells led to significant removal of hydroxycinnamic acids and lignin, resulting in marked enhancement of cellulose conversion by cellulases.

The Effect of Cyclododecane on Carbon-14 Dating of Archaeological Materials

The impact of cyclododecane on the carbon-14 dating of archaeological materials was investigated using accelerator mass spectrometry. Two conservation-grade and two laboratorygrade cyclododecane samples were determined to be radiocarbon-free, indicating that the chemical is synthesized from petroleum-derived, rather than modern hydrocarbon sources. Radiocarbon dating of modern and archaeological gourd rind samples that were treated with cyclododecane produced the same results as for untreated samples. While the study does not demonstrate that residues are absent from cyclododecane-treated artifacts, it showed that the stringent sample cleaning protocols specifically designed to remove both burial and laboratory contaminants were sufficient to reduce cyclododecane residues to levels that would not interfere with radiocarbon dating.

Easy DNA extraction method and optimisation of PCR-Temporal Temperature Gel Electrophoresis to identify the predominant high and low GC-content bacteria from dairy products

Molecular fingerprinting of bacterial ecosystems has recently increased in food microbiology. The aim of this work was to develop a rapid and easy method to extract DNA from various cheeses, and to optimize the separation of low and high GC-content bacteria by PCR-Temporal Temperature Gel Electrophoresis (PCR-TTGE). Seventy six strains belonging to 50 of the most frequently encountered bacterial species in dairy products were used to construct a database. Specific PCR-TTGE ladders containing 17 species forming a regular scale were created. Amplicons of these species were sequenced and the GC-content plotted against the migration distance: the correlation coefficients obtained were r 2 = 0.97 and r 2 = 0.99, respectively for high and low GC-contents. The extraction method developed did not use any harmful solvent such as phenol/chloroform. The concentrations of DNA extracted from hard cooked and pressed cheeses, quantified by picogreen molecular probes, were between 0.7 and 6 μg/g for core samples and 8 to 30 μg/g for rind samples. Experimental as well as commercial dairy products were analysed using the developed method and the reproducibility of the profiles was 89%. The method appears to be particularly efficient in the characterization of the ecosystem of cheese rinds.

Peroxidase activity associated with suberization processes of the muskmelon (Cucumis melo) rind.

The rind of fruits of muskmelon (Cucumis melo L. var. reticulatus) contains a network of suberized tissue referred to as the 'netting', and peroxidase (EC 1.11.1.7) activity is necessary to the polymerization of the aromatic domain of suberin. Peroxidase activity increased dramatically during the early stages of melon fruit netting, and in fruits exhibiting incomplete netting, peroxidase activity was significantly higher in netted than in non-netted regions of the same fruit. Moreover, analysis of peroxidase activity in three varieties of smooth-rind melons (Cucumis melo var. inodorous) indicated lower levels of the activity in rind samples, taken throughout fruit development, than in rinds of netted varieties. Netting-associated anionic peroxidase (NAPOD) was isolated from the melon rind at an early stage of netting development, partially purified, microsequenced and its cDNA was cloned. It was found to be a single-copy gene within the genome of netted and smooth melon varieties, and highly homologous to other Cucurbitaceous anionic peroxidases. A high transcript level was only detected in the rind of the netted variety. Monitoring the gene expression of netting-associated anionic peroxidase, together with other enzymes involved in the netting will shed light on the molecular control of the suberization processes in the melon rind and in plants in general.

Modelling of French Emmental cheese water activity during salting and ripening periods

Water sorption isotherms of French Emmental cheese have been determined at various temperatures (between 4 and 28 °C) for core or rind samples taken at various ripening stages during a standard 74 days ripening period. The differences observed between all the experimental isotherms are probably due to the evolution of product composition during the cheese ripening. Experimental data concerning the water activity profiles for industrially processed Emmental cheese have been collected after different brining experiments carried out at usual temperature conditions (4–18 °C) and all along the ripening cycle. The local water activity profiles during the Emmental brining and ripening periods are strongly dependent on the local NaCl concentration distribution. All these profiles vary in relation to the process step and of the process time. For the brining step, a precise correlation was proposed to express the influence of the water content and of the NaCl concentration. For the ripening period, a more general correlation expressing the water activity as a function of the water, NaCl and free NH 2 group concentrations was fitted to our experimental data. This last correlation was able to interpret the activity profiles more precisely during an Emmental ripening cycle in industrial conditions than the physical models of sorption fitted to the water sorption curves.