title: Quantification of Lactobacillus in fermented milk by multivariate image analysis with least-squares support-vector machines.
abstract: This paper reports an approach for quantification of Lactobacillus in fermented milk, grown in a selective medium (MRS agar), by use of digital colour images of Petri plates easily obtained by use of a flatbed scanner. A one-dimensional data vector was formed to characterize each digital image on the basis of the frequency-distribution curves of the red (R), green (G), and blue (B) colour values, and quantities derived from them, for example lightness (L), relative red (RR), relative green (RG), and relative blue (RB). The frequency distributions of hue, saturation, and intensity (HSI) were also calculated and included in the data vector used to describe each image. Multivariate non-linear modelling using the least-squares support vector machine (LS-SVM) and a linear model based on PLS regression were developed to relate the microbiological count and the frequency vector. Feasibly models were developed using the LS-SVM and errors were below than 10% for Lactobacillus quantification, indicating the proposed approach can be used for automatic counting of colonies.
authors.affiliation: Chemistry Institute, Campinas State University, P.O. Box 6154, 13084-971, Campinas, SP, Brazil.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Borin
authors.forename: Marco Flôres
authors.initials: MF
authors.lastname: Ferrão
authors.forename: Cesar
authors.initials: C
authors.lastname: Mello
authors.forename: Lívia
authors.initials: L
authors.lastname: Cordi
authors.forename: Luiz C M
authors.initials: LC
authors.lastname: Pataca
authors.forename: Nelson
authors.initials: N
authors.lastname: Durán
authors.forename: Ronei J
authors.initials: RJ
authors.lastname: Poppi
mesh_terms: D000818:Animals; D001331:Automation; D015373:Bacterial Typing Techniques; D015169:Colony Count, Microbial; D005240:Feasibility Studies; D005285:Fermentation; D006801:Humans; D007778:Lactobacillus / Q000502:physiology*; D016018:Least-Squares Analysis; D008892:Milk / Q000382:microbiology*; D015233:Models, Statistical; D015999:Multivariate Analysis; D016011:Normal Distribution; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity