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The demand for preservative-free food products is rising, and biopreservation is a potential alternative to replace or reduce the use of chemical preservatives. The objectives of this study were to assess the antifungal activity of lactic acid bacteria (LAB; n = 98) and the efficacy and applicability of the chosen bioprotective cultures against fungal spoilers in dairy products. First, 14 antifungal strains were preliminarily screened by in vitro tests against Pichia pastoris D3, Aspergillus niger D1, Geotrichum candidum N1, Kluyveromyces marxianus W1, and Penicillium chrysogenum B1 and validated by challenge tests in yogurt, indicating that the fungal-inhibiting activity of LAB was species specific and yogurt fermented with antifungal LAB cultures was more effective in extending shelf life. Second, the chosen 14 LAB strains were identified by the 16S rDNA sequence analysis and carbohydrate fermentation test. The results were as follows: nine strains were Lactobacillus plantarum, three were Lactobacillus paracasei, one was Enterococus faecium, and one was Lactobacillus rhamnosus. Among them, active L. plantarum N7 was the chosen and studied factor affecting antifungal activity by using the response surface methodology. Finally, in situ tests were conducted to validate the activity of L. plantarum N7 in actual dairy products (whey beverages). Physicochemical and microbial indices of whey beverages during storage indicated that antifungal L. plantarum N7 could slow yeast growth and be candidates of interest for industrial applications. Nine strains of 98 LABs showed fungal-inhibiting activity in vitro and in yogurt. Glucose, time, and temperature were the factors affecting antifungal activity. The effect of 3% of L. plantarum N7 inhibited yeast growth best in whey beverages. [ABSTRACT FROM AUTHOR]

• A lateral flow test strip based on colloidal gold for multicomponent analysis was developed. • GM crops containing BT-Cry1Ab, BT-Cry1Ac and CP4 EPSPS could be detected simultaneously. • Visual detection limits for crops containing BT-Cry1Ab, Cry1Ac and CP4 EPSPS were 1%, 1% and 0.1%, respectively. • The method was rapid (within 10 min), high-throughput, easy to operate and provided visible detection results. A colloidal gold immunochromatographic strip (ICS) for simultaneous detection of multiple transgenic proteins, including CP4 EPSPS, BT-Cry1Ab and BT-Cry1Ac, was developed in this study. The sensitivity of the strip to the target protein was 5 ng/mL for CP4 EPSPS, 100 ng/mL for BT-Cry1Ab and Cry1Ac, respectively. Parallel analysis for maize, soybean, sugar beet and cotton showed the strip could detect 1% of transgenic content in crops containing BT-Cry1Ab and Cry1Ac, and, at least, 0.1% of content in crops containing CP4 EPSPS. The detection results for seed samples indicated the multicomponent analysis ICS had good accuracy. The analysis could be completed within 10 min and had the advantages of being high-throughput, easy to operate and visual detection. This is the first report of semi-quantitative ICS for detecting three transgenic proteins simultaneously. The developed approach may provide insights into the development of ICS for analyzing simultaneously multiple components in genetically modified crops. [ABSTRACT FROM AUTHOR]

Recombinase polymerase amplification (RPA) was first reported in 2006 and has recently been shown to improve the detection of genetically modified organisms (GMOs). This study developed a more efficient RPA-based and lateral flow test strip (LFD)-based platform for the detection of P–35S and T-nos for GMOs, circumventing the need for expensive instruments and technicians. Other methods were compared to our assay. The RPA forward and reverse primers were labeled with the fluorophore biotin, digoxin, and FITC at the 5′ end and quickly determined whether the sample contains P–35S and T-nos of GMOs using the RPA-LFD method at room temperature. Nine events of GMOs were collected to determine the specificity of the RPA-LFD method, including KMD1, MON531, Rf1, Kefeng6, RRS, Bt11, MON863, Bt176, and Ms1. The results showed that the limit of detection of RPA-LFD was 50 copies and 100 copies, which was consistent with the limit of detection of RPA-AGE. The specificity and stability among the nine events were consistent, respectively. Finally, the perfect fitness for the detection of the nine double-blind samples indicated that the detection method is practical. In conclusion, we developed a more sensitive, specific, and stable field screening method for determining the GMO content with large-scale field applications. • This study developed the RPA-LFD methods for 35s and nos elements detection. • The RPA primers were labeled with fluorophore biotin, digoxin, and FITC. • The limit of detection of RPA-LFD was 50 copies and 100 copies. • The RPA-LFD method is fit for rapid GMOs detection in the field. [ABSTRACT FROM AUTHOR]