R. Grappin
Institut national de la recherche agronomique
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Featured researches published by R. Grappin.
International Dairy Journal | 1997
R. Grappin; Eric Beuvier
Abstract Cheese made from raw milk represents an important proportion of the traditional cheeses, particularly in South European countries. Besides destruction of pathogenic bacteria, the most significant changes in milk relevant to cheesemaking, which are induced by pasteurization are: • a partial elimination of the milk microorganisms which may grow in cheese during ripening, • a partial or total activation or inhibition of the plasmin/plasminogen complex, cathepsin D, lipoprotein lipase and alkaline phosphatase. Enzymes from psychrotrophic bacteria, acid phosphatase and xanthine oxidase, which may be active during ripening, withstand pasteurization., • a slight (7%) denaturation of serum proteins and little or no modification of the cheesemaking properties (coagulation, acidification by lactic acid bacteria). From experimental work carried out on several cheese varieties, comparing pasteurized or microfiltered milk and raw milk cheeses, it was found that facultatively heterofermentative lactobacilli, Micrococcaceae , enterococci, and propionibacteria in Swiss-type cheese, are found at higher levels in raw milk cheese. The main biochemical modification of cheese during ripening concerns the nature and extent of proteolysis. Although there is no clear trend in the breakdown of α s1 - and β -caseins, milk pasteurization leads to a significant decrease of the amount of small peptides and free amino acids and to different HPLC profiles. Experiments carried out with sensory analysis show that, in all cases, pasteurized or microfiltered milk cheeses have received lower flavour intensity scores than raw milk cheeses. From this review, it is concluded that the indigenous milk microflora, with its diversity of species and strains, appears to be mainly responsible of the specific sensory properties of raw milk cheeses.
International Dairy Journal | 2001
Françoise Berthier; Eric Beuvier; A. Dasen; R. Grappin
The objectives of this work were to describe the diversity of mesophilic lactobacilli in Comte cheese at the strain and species levels, to determine the origin(s) of this non-starter microflora, and to get a collection of well characterised strains from Comte cheeses. Strains were isolated from milks, starter cultures and eight cheeses from two factories, with four cheeses made from the same vat in each factory. Strain and species assignations were performed with a combination of two PCR-based methods, amplification with the pairs of repetitive primers ERIC1/ERIC2 and REP–1R-Dt/REP2-D, and amplification with specific primers for Lactobacillus zeae, Lactobacillus paracasei and Lactobacillus rhamnosus. The reliability and reproducibility of these methods were assessed using 49 collection strains of mesophilic lactobacilli commonly detected in cheeses. A total of 488 isolates of mesophilic lactobacilli was collected and was assigned to 44 different strains and three different species. Lactobacillus paracasei and Lactobacillus rhamnosus were the predominant species in milks, starter cultures and cheeses, and constituted 98.7% of the isolates. Strain diversity was found at both individual cheese and factory levels. Thirteen and fifteen different strains were detected throughout cheesemaking and ripening in two individual cheeses made in different factories; only 11 different strains were detected in the two corresponding mature cheeses. The data strongly suggest that most mesophilic lactobacilli strains originate from raw milk.
International Journal of Food Microbiology | 2002
Yvette Bouton; Philippe Guyot; Eric Beuvier; Patrick Tailliez; R. Grappin
This study investigated the genotypic characteristics of selected and wild homofermentative thermophilic lactobacilli strains during ripening of Comté cheeses, made into two cheese plants. Both amplification and restriction analysis of the 16S rRNA gene (PCR-ARDRA) and classical biochemical tests were used to identify isolates. Diversity within homofermentative lactobacilli was not found in their species composition since the same two species Lactobacillus helveticus and L. delbrueckii susbp. lactis were isolated from cheeses. In cheeses made with natural whey starter, it appeared that the most likely sources of L. helveticus and L. delbrueckii susbp. lactis were the starter and raw milk, respectively. The examination of RAPD profiles of lactobacilli strains revealed 19 RAPD groups among 50 isolates, which were different from selected starter strains. Using RAPD, REP-PCR, and PFGE to identify selected starter strains during cheese ripening, we showed that L. helveticus decreased quickly while L. delbrueckii susbp. lactis sustained high viability during ripening. The use of selected L. delbrueckii susbp. lactis strains diminished the genetic diversity among strains isolated from cheese, probably in preventing the raw milk microflora from growing.
Lait | 1993
Yvette Bouton; Philippe Guyot; A. Dasen; R. Grappin
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Activité protéolytique de souches de lactobacilles thermophiles isolées de levains et de Comté. I. Validation sur minifromages des techniques de laboratoire Y Bouton, P Guyot, A Dasen, R Grappin
Journal of Dairy Research | 1994
Yvette Bouton; R. Grappin
Free amino groups produced during cheese ripening are used to indicate the extent of cheese proteolysis. Several studies have shown a high correlation between the level of free amino acids and the flavour of Gouda (Aston et al. 1983) or Comte (Grappin & Berdague, 1989). Measurement of the level of free amino acids seems useful for the investigation of flavour chemistry in cheese (Lemieux et al. 1990). The determination of N fractions is often used to estimate the degree of proteolysis in cheese, but since this procedure is laborious and time consuming several attempts have been made to replace it by more rapid methods (Ardo & Meisel, 1991). Since its introduction by Satake et al. (1960), the 2,4,6-trinitrobenzenesulphonic acid (TNBS) method has been widely used for the determination of free amino groups. Because TNBS does not react with the imino groups of histidine and proline or the hydroxyl groups of tyrosine, serine or threonine, it has been accepted as a selective reagent for primary amino groups (Burger, 1974). Measurement of N by Kjeldahl in the phosphotungstic acid (PTA)–sulphuric acid extract (Gripon et al. 1975) estimates the N of free amino acids and low molecular mass peptides. The purpose of this study was to compare the TNBS and PTA-soluble N methods in order to find out whether the TNBS procedure can replace that of PTA-soluble N in the determination of a cheese proteolysis index.
International Dairy Journal | 1993
R. Grappin; Dominique Lefier; A. Dasen; Sylvie Pochet
Abstract Gruyere de Comte is a Swiss-type, hard cheese, made of raw milk and produced exclusively in a limited area, in the East of France. Comte cheese is regularly salted on the surface throughout the ripening period, with simultaneous rubbing. This process leads to an important bacterial surface growth (10 11 CFU/g), a production of NH 3 (50 ppm), and a regular increase of the salt level. The kinetics of salt intake and its final level strongly influence the propionic fermentation and eye formation, as well as the primary proteolysis. Hydrolysis of α s 1 - CN decreases regularly with the salt level, whereas plasmin activity is maximum at 2·3% salt/moisture. Variations in the ripening time × temperature cycle influence the rate of hydrolysis of α s 1 - CN and to a lesser extent of β-CN. The improntance of the propionic fermentation increases with the temperature of ripening. The modifications of the rheological properties of Comte during ripening appear to be time × temperature dependent. Slit formation is closely related to cheese composition and also to the nature and extent of proteolysis. It was shown that when several of the following physicochemical characteristics: low moisture, high fat, high NaCl, low calcium and high level of protein breakdown are associated, the rheological properties are modified in such a way (increase of the shortness), that the cheeses are more likely to have slits. The relative importance of the anisotropy of the rheological properties explains the direction of the slits which are always parallel to the surfaces. A high correlation (r = 0·96) was found between the log of the fracture strain difference and the slit intensity. From all the results obtained in various studies, it appears that monitoring both the nature and extent of proteolysis through milk quality, cheese making, and ripening conditions, is a major challenge to produce regularly high quality Comte cheese.
Journal of Dairy Research | 1998
Didier Dupont; R. Grappin
Bovine plasmin (PLM) and its precursor plasminogen (PLG) are present in cheese, in which the proteinase is thought to play a significant role in proteolysis during ripening. PLM in cheese is usually assayed by enzymic techniques and concentrations are generally expressed as activities. In order to determine absolute concentrations of PLM and PLG in cheese, we have applied an ELISA previously developed for the differential determination of PLM and PLG in milk. The assay used two monoclonal antibodies, one specific for PLG and the other cross reacting with PLM and PLG. PLM concentration was obtained by subtracting the PLG concentration from the value for PLM plus PLG. The assay was evaluated in cheese by determining the total amount of PLG and PLM in milk used in the manufacture of eight semi-hard cheeses on a pilot plant scale, and comparing it with the total amount of PLG and PLM present in the eight corresponding wheys and unripened cheeses. Concentrations of PLG and PLM in 19 commercial cheeses were also determined. It was thus demonstrated that the ELISA made it possible to quantify PLM and PLG in milk and cheese and that PLM and PLG concentrations in cheese were highly dependent on the technology used for cheesemaking.
Journal of Dairy Science | 1998
Solange Buchin; V. Delague; G. Duboz; J.L. Berdague; Eric Beuvier; S. Pochet; R. Grappin
Lait | 1997
Y. Demarigny; Eric Beuvier; Solange Buchin; Sylvie Pochet; R. Grappin
Lait | 1989
Bruno Ribadeau-Dumas; R. Grappin