Antimicrobial packaging system for optimization of electron beam irradiation of fresh produce

This study evaluated the potential use of an antimicrobial packaging system in combination with electron beam irradiation to enhance quality of fresh produce. Irradiated romaine lettuce up to 3.2 kGy showed negligible (p > 0.05) changes in color, but texture and sensory attributes were less acceptable with increased dose. We established the antimicrobial effectiveness of various active compounds incorporated into the low-density polyethylene (LDPE)/polyamide films to increase radiation sensitivity of surrogate bacteria (Listeria innocua and Escherichia coli). All films showed inhibition zones in an agar diffusion test. In the liquid culture test, the active compounds reduced the specific growth rate and decreased final cell concentration of strains. Films incorporated with active compounds increased the radiation sensitivity of the tested strains, demonstrating their potential to reduce the dose required to control microbial contamination using electron beam technology. The active compounds maintained their antimicrobial activity by exposure to ionizing radiation up to 3 kGy. Antimicrobial activity of LDPE/polyamide films incorporated with transcinnamaldehyde was tested with fresh-cut romaine lettuce. Total aerobic plate counts (APC) and yeast and mold counts (YMC) were determined as a function of dose (0, 0.5, and 1.0 kGy) for 14 days of storage at 4ðC. Irradiation exposure significantly lowered APCs of lettuce samples by 1-log CFU/g compared to the non-irradiated controls; however, it only slightly reduced YMCs. The effectiveness of using irradiation with antimicrobial films was enhanced with increased radiation dose and transcinnamaldehyde concentration. Electron beam irradiation up to 20 kGy did not affect the tensile strength and toughness of the polymeric films. The filmâÂÂs flexibility and barrier properties were significantly improved by exposure to 20 kGy. The addition of an active compound did not affect the tensile strength and barrier properties of the films, but decreased the percent elongation-at-break and toughness, making them slightly more brittle. Ionizing radiation affected the release kinetics of the antimicrobial agent from the packaging material into a model food system. Irradiated films exhibited slower release rates than non-irradiated film by 69%. In addition, release rate was lower at 4úC by 62.6% than at 21-35úC. The pH of the simulant solution affected release rate with pH 4 yielding higher rates than pH 7 and 10

Evaluation of antioxidative/antimicrobial potential of Oriental nutraceutical herb extracts in raw and cooked goat meat and beef products

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references (leaves 74-85).Issued also on microfiche from Lange Micrographics.This study was conducted to determine the effects of alcohol extracts of several Oriental nutraceutical herbs on storage properties of raw and cooked ground goat meat and beef. White peony root, red peony root, sappanwood stem, rehmania root, moutan cortex root, angelica root, and rosemary leaves were dehydrated, extracted with 95% ethanol, and freed of the solvent. The sappanwood, moutan cortex, and rosemary samples contained the largest amounts of total phenolics. Extracts were added to ground goat meat, and treated meat samples were aerobically stored at 4°C for 6 days, with or without cooking. Each herbal extract was also added to ground beef at 0.25% (w/w), with or without adding NaCl at 2% (w/w), and stored as raw and cooked patties. Peony (red or white) root extracts, whether added at 0.5, 1, or 2% levels, showed strong antioxidant effects in cooked goat meat, decreasing TBARS content more than 90% at day 6. The extracts were less antioxidative in raw goat meat, lowering the day-6 TBARS content less than 50%. The extracts from rehmania root, sappanwood, and moutan cortex were as antioxidative as the extracts from red and white peony roots, decreasing the TBARS content in cooked goat meat more than 88% at day 6. When red peony root extract was evaluated for antimicrobial activity in raw goat meat, it decreased APCs at day 3, but not at day 6. Extracts from white and red peony roots, sappanwood, moutan cortex, and rosemary were highly antioxidative in both raw and cooked beef patties, decreasing TBARS more than 88% by day 6. However, rehmania and angelica root extracts were less inhibitory. The antioxidant activity of the herbal extracts correlated (P 0.05) with total phenolic levels. All the extracts, other than rosemary extract, showed no antimicrobial activity in raw beef patties at either day 3 or day 6, presumably due to the relatively high microbial counts found in the initial untreated meat. Rosemary extract decreased APCs only at day 3

Scale-up fabrication of a biodegradable PBAT/PLA composite film compatibilized with a chain extender for industrial agricultural mulch film application

Low-density polyethylene (LDPE) mulch films have become a prevalent practice in agriculture to increase crop yield. However, because of their high environmental impact after use, biodegradable plastic films are considered desirable alternatives in agroecosystems. Herein, a polybutylene adipate-co-terephthalate (PBAT) and polylactic acid (PLA) composite film compatibilized with a chain extender (CE) was prepared via a two-step extrusion process. First, PBAT and PLA were blended at different ratios in a laboratory-scale twin-screw extruder, and the PBAT/PLA blends (80/20 wt.%) compatibilized with 1 phr of CE exhibited the most comparable physicochemical properties. The CE integration into the PBAT/PLA binary blend significantly increased mechanical rigidity and strength (p ≤ 0.05). The enhanced compatibility between the immiscible polymers was verified through thermal and phase morphological analyses. The optimum composite was then produced using a pilot-scale extrusion system. The pilot-scale extruded optimal biodegradable mulch composite exhibited excellent water barrier properties, as evidenced by a water vapor permeability of 0.83 g mm/m2·day·kPa and a water contact angle of 93.77° These values surpassed those of commercially available biodegradable mulch films. Furthermore, it demonstrated a weight reduction of 2.9% during a 3-month period of soil burial, exhibiting durability compared to commercial biodegradable mulch films. These results suggest that the developed film has great potential for practical food and agricultural applications

Enhancement of the water-resistance properties of an edible film prepared from mung bean starch via the incorporation of sunflower seed oil

Abstract Mung bean starch (MBS)-based edible films with incorporation of guar gum (GG) and sunflower seed oil (SSO) were developed in this study. MBS, GG, and SSO were used as the main filmogenic biopolymer, thickener, and hydrophobicity-imparting substance, respectively. To investigate the effect of SSO content on the physicochemical, mechanical, and optical properties of the films, they were supplemented with various concentrations (0, 0.5, 1, and 2%, w/w) of SSO. Increasing SSO content tended to decrease tensile strength, elongation at break, crystallinity, water solubility, and the water vapor permeability; in contrast, it increased the oxygen transmission rate and water contact angle. Consequently, the incorporation of SSO into the matrix of MBS-based films decreased their mechanical strength but effectively enhanced their water-resistance properties. Therefore, the MBS-based film developed here can be properly used as an edible film in settings that require high water-resistance properties but do not call for robust mechanical strength

Intelligent pH indicator film composed of agar/potato starch and anthocyanin extracts from purple sweet potato.

International audienceA new colorimetric pH indicator film was developed using agar, potato starch, and natural dyes extracted from purple sweet potato, Ipomoea batatas. Both agar and potato starch are solid matrices used to immobilize natural dyes, anthocyanins. The ultraviolet-visible (UV-vis) spectrum of anthocyanin extract solutions and agar/potato starch films with anthocyanins showed color variations to different pH values (pH 2.0-10.0). Fourier transform infrared (FT-IR) and UV-vis region spectra showed compatibility between agar, starch, and anthocyanin extracts. Color variations of pH indicator films were measured by a colorimeter after immersion in different pH buffers. An application test was conducted for potential use as a meat spoilage sensor. The pH indicator films showed pH changes and spoilage point of pork samples, changing from red to green. Therefore, the developed pH indicator films could be used as a diagnostic tool for the detection of food spoilage

Green Tea Extract Enrichment: Mechanical and Physicochemical Properties Improvement of Rice Starch-Pectin Composite Film

The effects of green tea extract (GTE) at varying concentrations (0.000, 0.125, 0.250, 0.500, and 1.000%, w/v) on the properties of rice-starch-pectin (RS-P) blend films were investigated. The results showed that GTE addition enhanced (p < 0.05) the antioxidation properties (i.e., total phenolic content, DPPH radical scavenging activity, and ferric reducing antioxidant power) and thickness of the RS-P composite film. The darker appearance of the RS-T-GTE blend films was obtained in correspondence to the lower L* values. However, the a* and b* values were higher toward red and yellow as GTE increased. Though GTE did not significantly alter the film solubility, the moisture content and the water vapor permeability (WVP) of the resulting films were reduced. In addition, the GTE enrichment diminished the light transmission in the UV-Visible region (200–800 nm) and the transparency of the developed films. The inclusion of GTE also significantly (p < 0.05) lowered the tensile strength (TS) and elongation at break (EAB) of the developed film. The FT-IR spectra revealed the interactions between RS-P films and GTE with no changes in functional groups. The antimicrobial activity against Staphylococcus aureus (TISTR 764) was observed in the RS-P biocomposite film with 1% (w/v) GTE. These results suggested that the RS-P-GTE composite film has considerable potential for application as active food packaging

Effect of oxidized phenolic compounds on cross-linking and properties of biodegradable active packaging film composed of turmeric and gelatin

International audienceCross-linking effects of different phenolic substances (tannic acid, caffeic acid, and green tea extract) on mechanical and barrier properties of biodegradable films consisting of turmeric (Curcuma longa) and gelatin were investigated. The results showed that degree of protein cross-linking increased with concentration of oxidized phenolic compounds, resulting in denser and stiffer film structures. Cross-link formation led to higher tensile strength and lower elongation-at-break (%), water vapor permeability, and water solubility of films with formation of aggregations. However, at high concentrations of phenolic compounds, molecular mobility increased due to grafting/branching reactions resulting in plasticizing effect. The developed films were applied as active packaging materials to fresh ground pork to extend shelf life, demonstrating good antioxidant activity and preventing lipid oxidation of fresh pork. No significant difference (p > 0.05) was noted in the overall acceptability of all samples by sensory analysis

High-affinity pyrophosphate by a synergistic effect receptor metal coordination and hydrogen bonding in water

We have developed the tightest binding PPi receptor reported to date by a combination of metal coordination and hydrogen bonding interaction in water.close847