Polymerase chain reaction for diagnosis of dermatophyte and Scytalidium spp. onychomycosis.
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Arthrodermataceae↗
Biomedical subjects
C Lacroix
Publications and source records attributed to C Lacroix.
Increased stress tolerance of Bifidobacterium longum and Lactococcus lactis produced during continuous mixed-strain immobilized-cell fermentation.
AIMS: The effect of immobilization and long-term continuous culture was studied on probiotic and technological characteristics of lactic acid and probiotic bacteria. METHODS AND RESULTS: A continuous culture in a two-stage system was carried out for 17 days at different temperatures ranging from 32 to 37 degrees C, with a first reactor containing Bifidobacterium longum ATCC 15707 and Lactococcus lactis subsp. lactis biovar. diacetylactis MD immobilized separately in gel beads, and a second reactor operated with free cells released from the first reactor. The tolerance of free cells from both strains produced in the effluent medium of both reactors to hydrogen peroxide, simulated gastric and intestinal juices, antibiotics and nisin, and freeze-drying markedly increased with culture time and was generally higher after 6 days than that of stationary-phase cells produced during free-cell batch fermentations. The reversibility of the acquired tolerance of B. longum, but not L. diacetylactis, to antibiotics was shown during successive free-cell batch cultures. CONCLUSIONS: Free cells produced from continuous immobilized-cell culture exhibited altered physiology and increased tolerance to various chemical and physico-chemical stresses. SIGNIFICANCE AND IMPACT OF THE STUDY: Continuous culture with immobilized cells could be used to produce probiotic and lactic acid bacteria with enhanced technological and probiotic characteristics.
Anti-Bacterial Agents↗
3-hydroxypropionaldehyde: applications and perspectives of biotechnological production.
3-hydroxypropionaldehyde (3-HPA) forms, together with HPA-hydrate and HPA-dimer, a dynamic, multi-component system (HPA system) used in food preservation, as a precursor for many modern chemicals such as acrolein, acrylic acid, and 1,3-propanediol (1,3-PDO), and for polymer production. 3-HPA can be obtained both through traditional chemistry and bacterial fermentation. To date, 3-HPA has been produced from petrochemical resources as an intermediate in 1,3-PDO production. In vivo, glycerol is converted in one enzymatic step into 3-HPA. The 3-HPA-producing Lactobacillus reuteri is used as a probiotic in the health care of humans and animals. The biotechnological production of 3-HPA from renewable resources is desirable both for use of 3-HPA in foods and for the production of bulk chemicals. The main challenge will be the efficient production and recovery of pure 3-HPA.
Acrolein↗
Pneumocystis carinii pneumonia in patients with hematologic malignancies: a descriptive study.
Objectives. A retrospective multicentric study was conducted over a five-year period to evaluate the clinical and laboratory characteristics and outcome of patients with proven Pneumocystis carinii pneumonia (PCP) complicating hematologic malignancies.Results. The study included 60 HIV-negative patients with 18 non-Hodgkin's malignant lymphoma (30%), 13 chronic lymphocytic leukaemia (21.7%), 10 acute leukemia (16.6%), 5 multiple myeloma (8.3%), 4 Waldenström's diseases (6.6%), 4 chronic myeloid leukemia (6.6%), 3 myelodysplasia (5%), 2 Hodgkin's diseases (3.3%) and 1 thrombopenia. Bronchoalveolar lavage was diagnostic in all patients. Forty-nine patients received cytotoxic drugs (81.7%), 25 (41.7%) a long-term corticotherapy and 15 (25%) underwent bone marrow transplantation. Twenty-seven patients (45%) required admission in the intensive care unit, 35 (58.3%) received an adjunctive corticotherapy and 18 mechanical ventilation (30%). Twenty patients (33.3%) died of PCP. A previous long-term corticotherapy (p=0.04), high respiratory (p=0.05) and pulse rates (p=0.02), elevated C reactive protein (p=0.01) and mechanical ventilation (OR=13.37; IC: 1.9-50) were associated with a poor prognosis. Adjunctive corticotherapy did not modify the prognosis.Conclusions. These results suggest that PCP can occur during the course of various hematologic malignancies, not only lymphoproliferative disorders. Prognosis remains poor. The diagnosis should be advocated more frequently and earlier to improve the prognosis.
Adult↗
Kinetics of plasma and erythrocyte metformin after acute administration in healthy subjects.
OBJECTIVES: Although the existence of a deep compartment for metformin has long been hypothesized, there is still little direct information concerning metformin distribution in individual tissues in man. The only available study involves chronic metformin therapy. In that study, the measurement of metformin in erythrocytes provided a reliable indicator of metformin distribution and of potential accumulation. To determine the kinetics of metformin in plasma and in erythrocytes after acute oral administration, we performed the present study in healthy subjects after a single oral dose of metformin and compared the pharmacokinetics parameters in erythrocytes to those in plasma. METHODS: Six nondiabetic participants took the study dose of 850 mg metformin at 8: 00 AM after a non-standardized breakfast (i.e., as recommended in clinical practice). Blood samples were collected for metformin measurement in plasma and in erythrocytes at 0, 1, 2, 3, 4, 6, 9, 24, 33, 48, 57, and 72 h. RESULTS: Maximum metformin concentration was attained at 3.0 +/- 0.3 h in plasma and 4.7 +/- 0.5 h in erythrocytes. This difference was not significant. Metformin concentrations peaked at a maximum almost 6 times higher in plasma than in erythrocytes (1.7 +/- 0.1 and 0.3 +/- 0.0 mg/l, respectively). However, because the elimination half-life of metformin was much longer in erythrocytes (23.4 +/- 1.9 h vs. 2.7 +/- 1.2 h), there was no difference in area under the curve between plasma and erythrocytes. The distribution volume (plasma) was calculated to be 146 +/- 11 l. Plasma and erythrocytes concentration-time curves showed that metformin was not detectable in plasma 24 hours after the oral administration, while it remained detectable in erythrocytes up to 48 hours. Metformin concentrations crossed approximately 13 hours after having reached their maximum values in plasma, approximately 16 h after metformin intake. CONCLUSION: Having demonstrated the rapid elimination of metformin from plasma and its slow disappearance from erythrocytes, the presents results should contribute to adjustment of metformin dosage to renal function, assessment of drug compliance, and retrospective analysis (when blood samples are drawn with delay) of the link between metformin and development of lactic acidosis. Most importantly, the present findings should help to ascertain the optimal dosage of metformin, particularly in elderly patients.
Adult↗
Exopolysaccharide production during batch cultures with free and immobilized Lactobacillus rhamnosus RW-9595M.
AIMS: Exopolysaccharides (EPS) were produced by Lactobacillus rhamnosus RW-9595M during pH-controlled batch cultures with free cells and repeated-batch cultures with cells immobilized on solid porous supports (ImmobaSil). METHODS AND RESULTS: Cultures were conducted in supplemented whey permeate (SWP) medium containing 5 or 8% (w/w) whey permeate. For free-cell batch cultures in 8% SWP medium, very high maximum cell counts (1.3 x 10(10) CFU ml(-1)) and EPS production (2350 mg l(-1)) were measured. A high EPS production (1750 mg l(-1)) was measured after four cycles for a short incubation period of only 7 h. Several methods for immobilized biomass determination based on analysis of biomass components (proteins, ATP and DNA) were tested. The DNA analysis method proved to be the most appropriate under these circumstances. This method revealed a high maximum immobilized biomass of 8.5 x 10(11) CFU ml(-1) support during repeated immobilized cell cultures in 5% SWP. The high immobilized biomass increased maximum EPS volumetric productivity (250 mg l(-1) h(-1) after 7 h culture) compared with free-cell batch cultures (110 mg l(-1) h(-1) after 18 h culture). CONCLUSIONS: High EPS productions were achieved during batch cultures of Lact. rhamnosus RW-9595M in SWP medium, exceeding 1.7 g EPS per litre. Repeated-batch cultures with immobilized cells resulted in increased EPS productivity compared with traditional free-cell cultures. SIGNIFICANCE AND IMPACT OF THE STUDY: The study clearly shows the high potential of the strain Lact. rhamnosus RW-9595M and immobilized cell technology for production of EPS as a functional food ingredient.
Animals↗
Production of antibacterial substances by bifidobacterial isolates from infant stool active against Listeria monocytogenes.
AIMS: This study aimed to characterize new isolates of human bifidobacteria, evaluate some of their probiotic potential and to screen these isolates for their effectiveness at inhibiting Listeria monocytogenes in vitro. METHODS AND RESULTS: Thirty-four Bifidobacterium isolates from infant faeces were identified by fructose-6-phosphate phosphoketolase and PCR. Six isolates, coded RBL67, RBL68, RBL69, RBL70, RBL85 and RBL86, showed higher antagonistic activity against L. monocytogenes. Neutralized culture supernatants of these strains did not inhibit L. monocytogenes when tested by agar diffusion method. However, the concentration of supernatant by speed-vac resulted in the formation of an inhibitory effect with supernatants from strains RBL67, RBL68 and RBL70. This effect was shown to be related to heat-stable proteinaceous compound(s) which were resistant to heating at 100 degrees C for 5 min but not to pronase-E, proteinase-K or trypsin. The extraction of the inhibitory compounds by methanol-acetone extraction procedure indicated that four strains (RBL67, RBL68, RBL69 and RBL70) were mostly soluble in acetone. However, strain RBL85 produced inhibitory substances that were soluble in methanol. CONCLUSION: Infant bifidobacterial isolates produce heat-stable proteinaceous compounds active against L. monocytogenes. SIGNIFICANCE AND IMPACT OF THE STUDY: Production of antibacterial substances by bifidobacteria would improve intestinal bacterial ecology and inhibit intestinal pathogens.
Antibiosis↗
Measurement of metformin concentration in erythrocytes: clinical implications.
AIMS: Although pharmacokinetics studies have long suggested a deep compartment for the antidiabetic drug metformin, there is still little information concerning metformin accumulation by individual tissues in man. In the present study, the erythrocyte was chosen to represent this putative deep compartment and metformin concentration in erythrocytes (EM) was compared with that in plasma (PM) to delineate clinical implications. METHODS: A reference group of 58 patients with well-tolerated metformin treatment was studied to provide standard mean metformin concentrations in the fasting state. Secondly, to provide transverse data reflecting clinical practice, the authors reviewed an investigation group of 93 metformin-treated patients with available PM and EM, which had been requested either to adjust metformin dosage to renal function, or to screen for potential metformin accumulation following renal failure, metformin overdose or lactic acidosis. Thirdly, the case of an individual with major metformin accumulation was studied to provide information about metformin elimination. RESULTS: From the bulk of data, we performed three types of analyses: (1) PM and EM were compared. In the investigation group, this comparison was extended to subgroups separated according to low-to-normal, moderately increased or highly increased metformin concentration. (2) Correlative analyses of PM, EM and serum creatinine were performed. (3) A kinetic study of the spontaneous decline of PM and EM was conducted. PM and EM were, respectively, 0.5 +/- 0.4 mg/l and 0.8 +/- 0.4 mg/l in the reference group, and 11.7 +/- 17.8 mg/l (mean +/- SD, range 0.0-71.9 mg/l) and 7.5 +/- 9.4 mg/l (0.0-34 mg/l) in the investigation group, mean serum creatinine of which was 290 +/- 258 micro mol/l. In the low-to-normal PM subgroup (n = 28), PM and EM were, respectively, 0.39 +/- 0.38 mg/l and 0.84 +/- 0.68 mg/l (p < 0.001). In the moderately increased PM subgroup (from therapeutic concentrations +2 SD to 5 mg/l, n = 24), PM and EM were 2.82 +/- 1.13 mg/l and 2.72 +/- 2.03 mg/l (NS). In the sharply increased PM subgroup (> 5 mg/l, n = 41), PM and EM were 27.6 +/- 23.2 mg/l and 17.0 +/- 11.4 mg/l (p = < 0.001). PM and EM were tightly correlated (r = 0.72 in the reference group and r = 0.90 in the investigation group, p < 0.001 for both). Metformin concentrations were also correlated with those of serum creatinine, but more so in the investigation group; in subgroups, a positive correlation was found only at high metformin concentrations and in erythrocytes. The kinetic study performed in the patient with major metformin accumulation showed that PM and EM dropped within less than 3 days from a maximum concentration of 80.0 mg/l and 20.4 mg/l, respectively, to 0.67 mg/l and 6.52 mg/l. CONCLUSIONS: In conclusion, metformin appears to accumulate in erythrocytes and, consequently, may be part of a deep compartment for the drug. This evidence of slow decline in erythrocyte metformin concentration may contribute to retrospective diagnosis of metformin accumulation and to refinements in adjusting metformin dosage to renal function.
Adult↗
Impact of nisin producing culture and liposome-encapsulated nisin on ripening of Lactobacillus added-Cheddar cheese.
This study aimed to evaluate the effects of incorporating liposome-encapsulated nisin Z, nisin Z producing Lactococcus lactis ssp. lactis biovar. diacetylactis UL719, or Lactobacillus casei-casei L2A adjunct culture into cheese milk on textural, physicochemical and sensory attributes during ripening of Cheddar cheese. For this purpose, cheeses were made using a selected nisin tolerant cheese starter culture. Proteolysis, free fatty acid production, rheological parameters and hydrophilic/hydrophobic peptides evolution were monitored over 6 mo ripening. Sensory quality of cheeses was evaluated after 6 mo. Incorporating the nisin-producing strain into cheese starter culture increased proteolysis and lipolysis but did not significantly affect cheese rheology. Liposome-encapsulated nisin did not appear to affect cheese proteolysis, rheology and sensory characteristics. The nisinogenic strain increased the formation of both hydrophilic and hydrophobic peptides present in the cheese water extract. Sensory assessment indicated that acidic and bitter tastes were enhanced in the nisinogenic strain-containing cheese compared to control cheese. Incorporating Lb. casei and the nisinogenic culture into cheese produced a debittering effect and improved cheese flavor quality. Cheeses with added Lb. casei and liposome-encapsulated nisin Z exhibited the highest flavor intensity and were ranked first for sensory characteristics.
Cheese↗
[Differential diagnosis of onychomycosis].
In order to give an effective treatment to a patient with nail disorders, a correct aetiological diagnosis is necessary. Distal and lateral thickening of nail bed and nail plate with onycholysis, deep or superficial leuconychia, melanonychia, paronychia, distal and lateral onycholysis, and total dystrophic onychomycosis are the common physical signs of onychomycosis which represent 50 per cent out of nails disorders. Nail disorders due to cutaneous or general diseases with similar alteration of nail configuration may be confused with onychomycosis. In many cases, an aetiological trend is given by a total body examination of the skin and the mucosa. To diagnose correctly a non fungal nail disorder from an onychomycosis sometimes is a real challenge. According non fungal nail disorder and fungal nail infection may be associated, so a mycological examination and sometimes histopathological examination are very helpful to establish a good diagnosis.
Diagnosis, Differential↗
Bifidobacterium longum ATCC 15707 cell production during free- and immobilized-cell cultures in MRS-whey permeate medium.
Bifidobacterium longum ATCC 15707 cell production was studied in MRS medium supplemented with whey permeate (MRS-WP) during free-cell batch fermentations and continuous immobilized-cell cultures. Very high populations were measured after 12 h batch cultures in MRS-WP medium controlled at pH 5.5 (1.7+/-0.5x10(10) cfu/ml), approximately 2-fold higher than in non-supplemented MRS. Our study showed that WP is a low-cost source of lactose and other components that can be used to increase bifidobacteria cell production in MRS medium. Continuous fermentation in MRS-WP of B. longum immobilized in gellan gum gel beads produced the highest cell concentrations in the effluent (4.9+/-0.9x10(9) cfu/ml) at a dilution rate (D) of 0.5 h(-1). However, maximal volumetric productivity (6.9+/-0.4x10(9) cfu ml(-1)h(-1)) during continuous cultures was obtained at D =2.0 h(-1), and was approximately 9.5-fold higher than during free-cell batch cultures at an optimal pH of 5.5 (7.2x10(8) cfu ml(-1)h(-1)).
Bifidobacterium↗
Analysis of underlying diseases and prognosis factors associated with Pneumocystis carinii pneumonia in immunocompromised HIV-negative patients.
The aim of this retrospective study was to determine the underlying diseases associated with Pneumocystis carinii pneumonia (PCP) in immunocompromised HIV-negative patients and to identify prognosis factors in this population. One hundred three cases of PCP were diagnosed over a 5-year period. Diagnosis was established on the basis of clinical features and by detection of Pneumocystis carinii cysts in bronchoalveolar lavage fluid. Underlying diseases comprised hematologic malignancies (n=60; 58%), inflammatory diseases (n=27; 26%), and solid tumors (n=18; 17.5%); 9 (8%) patients were solid organ transplant recipients. Seventy-one (69%) patients received cytotoxic drugs, 57 (55%) were treated with long-term corticotherapy, and 15 (14.7%) underwent bone marrow transplantation. Fifty-eight (56%) patients were admitted to the intensive care unit, and 52 (41%) required mechanical ventilation. Thirty-nine (38%) patients died of PCP; data from these patients were compared with those from surviving patients. The following factors were associated with a poor prognosis: high respiratory rate (P=0.005), high pulse rate (P=0.0003), elevated C-reactive protein (P=0.01), elevated serum lactate dehydrogenase level (P=0.02), and mechanical ventilation (OR, 14.4; 95%CI, 5-50). The results suggest that PCP can occur during the course of many immunosuppressive diseases, particularly various hematologic malignancies. The diagnosis of PCP should be considered more frequently and advocated earlier in immunocompromised HIV-negative patients, since prompt diagnosis may improve the prognosis of these patients.
Adolescent↗
Quantitative determination of the spatial distribution of pure- and mixed-strain immobilized cells in gel beads by immunofluorescence.
A new method was developed to detect and quantify two strains, Lactococcus lactis subsp. lactis biovar. diacetylactis MD and Bifidobacterium longum ATCC 15707, immobilized separately and co-immobilized in gel beads, using specific polyclonal antibodies and confocal laser-scanning microscopy. The establishment of biomass concentration profiles for each strain was measured during colonization of beads using successive pH-controlled batch fermentations. Growth occurred preferentially in 200- and 300-microm peripheral layers of the beads for L. diacetylactis and B. longum, respectively. Repeated-batch cultures with immobilized cells permitted the production of a mixed culture containing a non-competitive strain of bifidobacteria, as a result of immobilized-cell growth and high cell-release activity from the beads. During co-immobilized fermentations, there were no apparent interactions between the strains.
Bifidobacterium↗
Tinea pedis in European marathon runners.
BACKGROUND: Epidemiological studies suggest that 15% of the population in industrial countries suffer from tinea pedis (athlete's foot) and that persons who do sports are a high-risk population. OBJECTIVE: To investigate the responsibility of dermatophytes in interdigital lesions of the feet in European marathon runners and to identify associated risk factors. SUBJECTS AND METHODS: Runners of the 14th Médoc Marathon (n = 147) were interviewed on risk factors for tinea pedis and underwent physical and mycological examinations. RESULTS: Interdigital lesions of the feet were found in 66 runners (45%). A dermatophyte was isolated in 45 runners (31%), 12 of whom were asymptomatic. Trichophyton interdigitale and T. rubrum accounted for 49% and 35.5%, respectively, of the cases of tinea pedis. Thirty-three (22%) of the 102 runners free of dermatophyte infection had lesions resembling those of tinea pedis. Increasing age and use of communal bathing facilities were predictive of T. rubrum culture. CONCLUSIONS: Marathon runners are at high risk for tinea pedis, but dermatophytes are responsible for only half of the foot lesions found in runners. The existence of asymptomatic carriers calls for prophylactic measures.
Adult↗
Inflammatory myositis associated with anti-U1-small nuclear ribonucleoprotein antibodies: a subset of myositis associated with a favourable outcome.
OBJECTIVES: Inflammatory myositides are rare chronic disorders which may be either isolated or associated with other conditions such as connective tissue diseases or neoplasia. A large variety of autoantibodies can be detected in patients with myositis, some of which have a diagnostic and/or a prognostic value. Myositis associated with anti-U1-small nuclear ribonucleoprotein antibodies (anti-U1-snRNP Abs) are usually considered as overlapping syndromes, mainly mixed connective tissue diseases (MCTD) in which muscle symptoms occur insidiously during the disease course and are characterized by a favourable outcome. METHODS: The clinical, biological, immunological and pathological findings as well as the outcome of five patients with anti-U1-snRNP-associated myositis were retrospectively analysed. RESULTS: Patients were mainly black females. In all five patients, myositis was the predominant manifestation at presentation. Associated conditions consisted of interstitial lung disease (ILD) (three), arthritis (three) and neurological symptoms (two). No patient presented Raynaud's phenomenon nor met criteria for MCTD. Biological inflammatory features, rheumatoid factor and polyclonal hypergammaglobulinaemia were present in all cases. Besides anti-U1-snRNP Abs, one patient had anti-Ro/SSA and anti-La/SSB Abs at presentation and one additional patient developed anti-double-stranded-DNA and anti-Sm Abs after a follow-up of more than 4 yr. No patient had anti-PM/sclerosis (Scl) nor anti-aminoacyl-tRNA synthetase Abs. All patients dramatically improved with steroids, and reached complete remission (CR) within 3 weeks. Two patients relapsed 18 months after CR. They both reached rapidly second CR using steroids associated or not with oral methotrexate. CONCLUSION: Our data suggest that anti-U1-snRNP Abs may define a subset of myositis characterized by a favourable outcome, though often associated with ILD and/or neurological manifestations.
Adult↗
Antibacterial activities of nisin Z encapsulated in liposomes or produced in situ by mixed culture during cheddar cheese ripening.
This study investigated both the activity of nisin Z, either encapsulated in liposomes or produced in situ by a mixed starter, against Listeria innocua, Lactococcus spp., and Lactobacillus casei subsp. casei and the distribution of nisin Z in a Cheddar cheese matrix. Nisin Z molecules were visualized using gold-labeled anti-nisin Z monoclonal antibodies and transmission electron microscopy (immune-TEM). Experimental Cheddar cheeses were made using a nisinogenic mixed starter culture, containing Lactococcus lactis subsp. lactis biovar diacetylactis UL 719 as the nisin producer and two nisin-tolerant lactococcal strains and L. casei subsp. casei as secondary flora, and ripened at 7 degrees C for 6 months. In some trials, L. innocua was added to cheese milk at 10(5) to 10(6) CFU/ml. In 6-month-old cheeses, 90% of the initial activity of encapsulated nisin (280 +/- 14 IU/g) was recovered, in contrast to only 12% for initial nisin activity produced in situ by the nisinogenic starter (300 +/- 15 IU/g). During ripening, immune-TEM observations showed that encapsulated nisin was located mainly at the fat/casein interface and/or embedded in whey pockets while nisin produced by biovar diacetylactis UL 719 was uniformly distributed in the fresh cheese matrix but concentrated in the fat area as the cheeses aged. Cell membrane in lactococci appeared to be the main nisin target, while in L. casei subsp. casei and L. innocua, nisin was more commonly observed in the cytoplasm. Cell wall disruption and digestion and lysis vesicle formation were common observations among strains exposed to nisin. Immune-TEM observations suggest several modes of action for nisin Z, which may be genus and/or species specific and may include intracellular target-specific activity. It was concluded that nisin-containing liposomes can provide a powerful tool to improve nisin stability and availability in the cheese matrix.
Anti-Bacterial Agents↗
Inhibition of Listeria innocua in cheddar cheese by addition of nisin Z in liposomes or by in situ production in mixed culture.
The effect of addition of purified nisin Z in liposomes to cheese milk and of in situ production of nisin Z by Lactococcus lactis subsp. lactis biovar diacetylactis UL719 in the mixed starter on the inhibition of Listeria innocua in cheddar cheese was evaluated during 6 months of ripening. A cheese mixed starter culture containing Lactococcus lactis subsp. lactis biovar diacetylactis UL719 was selected for high-level nisin Z and acid production. Experimental cheddar cheeses were produced on a pilot scale, using the selected starter culture, from milk with added L. innocua (10(5) to 10(6) CFU/ml). Liposomes with purified nisin Z were prepared from proliposome H and added to cheese milk prior to renneting to give a final concentration of 300 IU/g of cheese. The nisin Z-producing strain and nisin Z-containing liposomes did not significantly affect cheese production and gross chemical composition of the cheeses. Immediately after cheese production, 3- and 1.5-log-unit reductions in viable counts of L. innocua were obtained in cheeses with encapsulated nisin and the nisinogenic starter, respectively. After 6 months, cheeses made with encapsulated nisin contained less than 10 CFU of L. innocua per g and 90% of the initial nisin activity, compared with 10(4) CFU/g and only 12% of initial activity in cheeses made with the nisinogenic starter. This study showed that encapsulation of nisin Z in liposomes can provide a powerful tool to improve nisin stability and inhibitory action in the cheese matrix while protecting the cheese starter from the detrimental action of nisin during cheese production.
Cheese↗
Statistical data validation methods for large cheese plant database.
Production data of the cheesemaking process are used to monitor milk fat and protein recoveries in cheese, cheese yield, and composition and eventually to predict these parameters. Due to the large impact of these factors on cheese quality and plant profitability, it is very important to use reliable data for analysis, modeling, and control of the process. This paper tested six methods for detecting erroneous data in industrial cheesemaking databases. The data analyzed came from 4 yr of stirred-curd Cheddar cheese production in an industrial cheesemaking facility, comprising over 10,000 vats. Single vat outliers were detected using a simple statistical criterion of mean +/- 3.6 SD on single variable distributions, Fourier series modeling of seasonal variables (fat, protein, lactose, and total solids in milk, and protein in whey), and the multivariate Mahalanobis outlier analysis. Detection of outlier productions (corresponding to several vats) was done by applying the mean +/- 3.6 SD criterion to variables obtained through calculating the fat mass balance, fat retention coefficient, and yield efficiency. Data treatment enabled the detection of outlier data, but also pinpointed variables with a low reliability (manually registered times). Single variable and multivariable methods proved complementary, and the use of both types of methods is recommended when validating an existing database.
Analysis of Variance↗