Rapid Detection and Differentiation of Alicyclobacillus Species in Fruit Juice Using Hydrophobic Grid Membranes and Attenuated Total Reflectance Infrared Microspectroscopy

Abstract

Pasteurized juices may undergo spoilage during normal shelf life due to Alicyclobacillus spp. Metabolic byproducts during germination of these thermoacidiophilic, endospore-forming bacteria impart off-flavors. The objective was to develop a simple, rapid, and sensitive approach for differentiation of Alicyclobacillus spp. by attenuated total reflectance infrared (ATR-IR) microspectroscopy after isolation onto hydrophobic grid membrane (HGM) filters. Dilutions of four different species of Alicyclobacillus were filtered onto HGM, incubated on orange serum agar (50 degrees C, 36-48 h), and dried under vacuum. Spectra were collected using ATR-IR microspectroscopy and analyzed by multivariate analysis. Results indicated that soft independent modeling of class analogy models exhibited clusters that permitted classification at species and strain levels. The methodology was validated by correctly predicting Alicyclobacillus (100%) in blind tests. The proposed procedure permits chemically based classification of intact microbial cells. Implementation provides the juice industry with a rapid screening procedure to detect and monitor Alicyclobacillus that threatens the quality of pasteurized juices.

Rapid detection and quantification of milk adulteration using infrared microspectroscopy and chemometrics analysis

“…In addition to providing a means of classifying objects, residuals provide valuable information regarding class homogeneity, separation between classes (interclass distance), and the relative strength of any given variable to model the structure of a class or to discriminate between classes (discriminating power). SIMCA's interclass distance (ICD) describes quantitatively the similarity or dissimilarity of the different classes, being generally accepted that samples can be differentiated when ICD >3 (Grasso et al, 2011). The discriminating power of variables may be used to eliminate noise from the data set, such that variables having both low discriminating power and modelling power can be eliminated.…”

“…MIR-microspectroscopy has been successfully applied in detecting subtle compositional differences between microorganisms at strain and serovar level (Grasso, Yousef, De Lamo Castellvi, & Rodriguez-Saona, 2011;Prabhakar, Kocaoglu-Vurma, Harper, & Rodriguez-Saona, 2011) and results showed that this technology could provide rapid, simple and reliable screening procedure for the industry.…”

The Development of Infrared Microspectroscopy (IMS) and Its Applications in Agricultural and Aquatic Products

“…The results showed that the bacteria could be classified at species and strain levels by soft independent modeling. The accuracy of the model in correctly predicting Alicyclobacillus reached 100% in blind tests (62).…”

“…Rapid detection of bacteria in the industrial production of juice is important. In 2009, IMS in ATR mode was used to study the rapid detection and differentiation of Alicyclobacillus species in fruit juice (62). The data were analyzed by multivariate analysis.…”

Attenuated total reflectance infrared microspectroscopy combined with multivariate analysis, a novel tool to characterize cleaning efficiency of organic microfiltration membranes

“…Fourier transform infrared microspectrsocpy (FT-IRMS) combined with multivariate data analysis is a well known method for the analysis of chemicals and microorganisms [13,14]. Specifically, attenuated total reflectance infrared microspectroscopy (IRMS) has the potential of detecting subtle compositional differences between samples.…”