Rice bran, an economical, underutilized coproduct of rough rice milling, was used to produce peptide hydrolysates, which were investigated for anticancer activity. Protein hydrolysates prepared by Alcalase hydrolysis under optimized conditions were treated further to obtain gastrointestinal (GI)-resistant peptide hydrolysates. They were fractionated into >50, 10-50, 5-10, and <5 kDa sizes and evaluated for inhibitory activity on proliferation of human colon (Caco-2) and liver (HepG2) cancer cell lines by Trypan blue dye exclusion assay. GI-resistant <5 and 5-10 kDa sized peptide fractions inhibited growth of Caco-2 cells by 80%, and the <5 kDa fraction inhibited growth of HepG2 cells by approximately 50% compared to controls and nonresistant fractions. An MTS cell titer assay confirmed antiproliferative effects of the peptide fractions. The results demonstrated that 5-10 and <5 kDa sized GI-resistant fractions promoted significant (p < 0.05) inhibitory activities on both cancer cell lines compared to controls. More investigations are needed to show such value-added effects on the technofunctional and sensorial properties of the food protein and peptide matrices.

Listeria monocytogenes is an important foodborne pathogen with a persistent ability to form biofilm matrices in the food processing environments. In this study, we have determined the ability of bacteriophage P100 to reduce L. monocytogenes cell populations under biofilm conditions by using 21 L. monocytogenes strains representing 13 different serotypes. There were considerable differences in the ability of various strains of L. monocytogenes to form biofilms, with strains of serotype 1/2a showing maximum biofilm formation. Irrespective of the serotype, growth conditions, or biofilm levels, the phage P100 treatment significantly reduced L. monocytogenes cell populations under biofilm conditions. On the stainless steel coupon surface, there was a 3.5- to 5.4-log/cm2 reduction in L. monocytogenes cells by phage treatment. These findings illustrate that phage P100 is active against a wide range of L. monocytogenes strains in biofilm conditions.

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Bacteriophage Listex P100 (phage P100) was approved by the U.S. Food and Drug Administration and U.S. Department of Agriculture's Food Safety and Inspection Service for Listeria monocytogenes control on both raw and ready-to-eat food products. In this article, we present the proof of concept on the influence of phage dose, phage contact time, and storage temperature on the listericidal activity of phage P100 in reducing the L. monocytogenes loads on the surface of fresh channel catfish fillet. The fresh catfish fillet samples were surface inoculated with approximately 4.3 log(10) colony forming units (CFU)/g of a two serotype mix (1/2a and 4b) of L. monocytogenes cells and then surface treated with phage P100. L. monocytogenes reduction was influenced by phage contact time and phage dose regardless of higher or lower temperature regimes tested on catfish fillet. The reduction in L. monocytogenes loads (p < 0.05) with the phage P100 dose of 2 x 10(7) plaque forming units (PFU)/g (7.3 log(10) PFU/g) was 1.4-2.0 log(10) CFU/g at 4 degrees C, 1.7-2.1 log(10) CFU/g at 10 degrees C, and 1.6-2.3 log(10) CFU/g at room temperature (22 degrees C) on raw catfish fillet. The phage contact time of 30 min was adequate to yield greater than 1 log(10) CFU/g reduction in L. monocytogenes, whereas 15 min contact time with phage yielded less than 1 log(10) CFU/g reduction in L. monocytogenes loads on catfish fillet. Phage P100 titer was stable on catfish fillet samples, and overall reductions in L. monocytogenes counts were still maintained over a 10-day shelf life at 4 degrees C or 10 degrees C by phage P100 treatment. These findings illustrate the effectiveness of an alternative generally recognized as safe antimicrobial such as bacteriophage Listex P100 in quantitatively reducing L. monocytogenes from fresh catfish fillet surfaces.