Determination of microbiological contamination sources during ice cream production in Denizli, Turkey

Surveillance and examination of microbial contamination in ice cream in China

This study investigated the microbial contamination of ice cream in China. A total of 2,887 ice cream samples were collected from different regions of China. Contamination by the aerobic plate count (APC), coliforms, and three foodborne pathogens, such as Listeria monocytogenes, Staphylococcus aureus, and Salmonella spp., was detected in the samples. L. monocytogenes isolates were further analyzed for antibiotic susceptibility and multi-locus sequence typing (MLST). The results showed that APC was more than 10 5 CFU/g in 6.10% (176/2887) and coliform was more than 10 2 CFU/g in 15.69% (453/2887) of all samples. The positive rates of S. aureus, L. monocytogenes, and Salmonella spp. were 0.66%, 0.62%, and 0.10%, respectively. Of these, S. aureus contamination was more than 10 2 CFU/g in two samples, and L. monocytogenes in the positive sample was in the range of 0.3–240 MPN/g, with a median of 4.3 MPN/g. The hygienic status of the packaged samples was much better than that of the bulk samples (P < 0.05). Catered samples were more frequently and heavily contaminated than samples from retail and wholesale outlets (P < 0.05). No significant differences were observed in samples bought from urban and rural areas (P >0.05). For 18 L. monocytogenes strains isolated from ice cream, the resistance rate of nine antibiotics was 5.56% (1/18). By MLST, the L. monocytogenes strains were classified into 9 sequence types (STs), of which ST8 was most common (6 isolates). These above results indicate that a potential health risk to the public may be caused by ice cream, particularly susceptible populations.

Effect of Hibiscus sabdariffa and Camellia synensis extracts on microbial, antioxidant and sensory properties of ice cream

Herbal extracts have been widely used by consumers for food fortification and medical purposes worldwide and are focused in traditional medicine in recent years. At this study, we aimed to examine the antimicrobial, antioxidant and sensory characteristics of ice creams fortified with different combinations of Hibiscus sabdariffa and Camellia synensis determined by Design of Experiments software. Levels of 10-100 and 40-400 mg/kg for Hibiscus sabdariffa and Camellia synensis extracts, respectively, were selected and experiments were conducted by central composite design. Generally, 13 runs were introduced by the software and followed in laboratory for analysis. Antimicrobial activity was studied against Escherichia coli and Staphylococcus aureus as indicators of gram negative and gram positive bacteria. Results showed that all combinations were active against both bacteria but Staphylococcus aureus was more sensitive than Escherichia coli. Importantly, Camellia synensis was more effective than Hibiscus sabdariffa in both antimicrobial and antioxidant experiments but sensory panelists selected the sample containing lowest concentrations of both extracts. However, frequent consumption of low-dose fortified dairies with Hibiscus sabdariffa and Camellia synensis could be helpful for consumers interested in functional foods.

Light microscopy and scanning electron microscopy of bacterial colonies isolated from ras malai samples from different markets of Lahore, Pakistan

The current study investigates the total bacterial contamination in various packed and unpacked ras malai samples of 14 different localities of Lahore, Pakistan. The bacterial colonies such as Bacillus sp. and Gamella sp. were isolated from ras malai samples and grown on agar-broth media under sterile environmental conditions. Serial dilution technique was used to compose the replicates to get a viable count of bacteria in the samples. Results indicated that in case of packed ras malai samples, maximum bacterial count was observed in Sample 1 (422 × 10^-2 to 402 × 10^-6 ) and minimum bacterial count was in Sample 4 (21 × 10^-2 to 9.3 × 10^-6 ). For unpacked ras malai samples, maximum bacterial count was in Sample 3 (200.3 × 10^-2 to 181.3 × 10^-6 ) and minimum bacterial count was observed in Sample 1 (110 × 10^-2 to 90.4 × 10^-6 ). It was concluded that the marketed samples contain more bacterial count as compared to the standard sterilization values. Such products could possibly become the cause of many health problems in children.

Yeasts isolated from tropical fruit ice creams: diversity, antifungal susceptibility and adherence to buccal epithelial cells

Abstract Fruit-based ice creams are products widely consumed in tropical countries and, because of their composition, can be a good source for microbial growth, including opportunistic pathogens. The aims of this study were to characterize the yeast populations present in Brazilian fruit-based ice creams, and to investigate the antifungal susceptibility to amphotericin B, fluconazole and itraconazole, and the ability of the isolates that were able to grow at 37 ºC to adhere to buccal epithelial cells (BEC). Two hundred and sixty-seven yeast isolates obtained from the ice cream samples were identified as belonging to 29 species, with counts that ranged from 1.5 to 5.2 log CFU/mL. The predominant species were Candida intermedia, Torulaspora delbrueckii, C. parapsilosis, Clavispora lusitaniae, Saccharomyces cerevisiae and Pichia kudriavzevii. At least 16 yeast species isolated in this study have been reported as opportunistic pathogens. Forty-one yeast isolates showed resistance or dose-dependent susceptibility to at least one of the antifungal drugs tested. One isolate of C. parapsilosis was resistant to all the antifungals tested and showed ability to adhere to BEC. The percentage of adhesion to BEC was high mainly for isolates of P. kudriavzevii, Meyerozyma guilliermondii, C. parapsilosis, S. cerevisiae and Debaromyces hansenii. The data suggest that the presence of these opportunistic yeasts as contaminants in ice creams may represent a potential risk to the final consumer, especially to immunocompromised individuals who may consume these products.

Predicting Shelf-life of Ice Cream by Accelerated Conditions

Shelf-life is defined as the amount of time during which a food product retains its desired sensory, chemical, and physical characteristics while remaining safe for consumption. The food industry needs to rapidly obtain the necessary information for determining the shelf life of its products. Here we studied the approaches available for conducting accelerated shelf-life tests. Accelerated shelf-life testing is applied to a variety of products to rapidly estimate change in characteristics with time. The aim of this work was to use accelerated shelf-life testing to study the changes in pH, microbiology, and sensory characteristics of ice cream by the application of a kinetic approach and, based on the observations, to estimate its shelf life. As per the current law, there is no shelf life on ice cream. Our results suggest that the shelf life of an ice cream sample was 24.27 months at –18℃, 2.29 months at –6℃, 0.39 months at –1℃, and 0.15 months at 4℃. Results of this study suggest that a set expiration date on ice cream might also contribute to effective management of ice cream characteristics in the retail chilled chain.

The implementation of HACCP management system in a chocolate ice cream plant

To guarantee the safety of chocolate ice cream production, the Hazard Analysis Critical Control Points (HACCP) system was applied to the production process. The biological, chemical, and physical hazards that may exist in every step of chocolate ice cream production were identified. In addition, the critical control points were selected and the critical limits, monitoring, corrective measures, records, and verifications were established. The critical control points, which include pasteurization and freezing, were identified. Implementing the HACCP system in food manufacturing can effectively ensure food safety and quality, expand the market, and improve the manufacturers’ management level.

Antistaphylococcal effect of enterocin AS-48 in bakery ingredients of vegetable origin, alone and in combination with selected antimicrobials

The inhibitory effect of enterocin AS-48 against Staphylococcus aureus was investigated in various types of bakery ingredients. Antibacterial activity greatly depended on the food substrate, ranging from complete inactivation of S. aureus in liquid caramel (in which the bacterium survived poorly) to no significant inhibition (as in vanilla or chocolate creams). Significant reductions of viable counts in the range of 1.8 to 2.7 log units (P < 0.05) were achieved in substrates like pumpkin confiture or diluted almond cream stored at temperatures of 10 or 22 degrees C. Given the very low activity detected in chocolate substrates, enterocin AS-48 was tested in combination with other antimicrobials. Bactericidal activity increased markedly for the combinations of AS-48 and 0.1% eugenol (v/v), 0.5% 2-nitropropanol (v/v), or 3% Nisaplin (w/v). Enterocin AS-48 could be applied in combination with other antimicrobials for preservation of bakery ingredients against S. aureus.