Controlling Listeria monocytogenes on ready-to-eat poultry products using carboxymethylcellulose film coatings containing green tea extract (GTE) combined with nisin and malic acid

The ability to control Listeria monocytogenes on ready-to-eat poultry products using carboxymethyl-cellulose film coatings containing green tea extract (GTE), malic acid (M), nisin (N), and their combinations was evaluated. The antimicrobials (GTE: 1.0%, nisin: 10,000 IU/g, malic acid: 1.0%) were incorporated alone or in combination into a carboxymethyl cellulose film coating. Pre-inoculated, fully cooked chicken pieces (~1g, 1cm x 1cm x 1cm) were coated with the film solution. The coated chicken pieces were stored at 4°C and the inhibitory activity against Listeria monocytogenes was evaluated at 0, 7, 14, 21, and 28 days. The highest inhibitory activity was found in the sample containing GTE, nisin, and malic acid in combination with a reduction of 3.3 log CFU/mL. These data demonstrate that GTE—combined with nisin and malic acid and incorporated into a carboxymethyl-cellulose film coating, multiple-hurdle technology—is effective in inhibiting L. monocytogenes growth on fully cooked chicken pieces at 4°C. Research in the area of finding natural antimicrobials to aid in the prevention of food-borne illnesses is necessary to improve safety and shelf life of products such as ready-to-eat meats. This project provides an effective combination of natural anti-microbials to control L. monocytogenes in ready-to-eat chicken pieces

Combined inhibitory effect of nisin with EDTA against Listeria monocytogenes in soy-protein edible coating on turkey frankfurters stored at 4°C and 10°C

Several food contamination outbreaks are linked to Listeria monocytogenes. More effective methods are needed to prevent the growth and recontamination of L. monocytogenes on ready-to-eat (RTE) food products. Therefore, the objectives of this study were to evaluate the inhibitory activities of nisin (10,000 IU/mL), EDTA (sodium Ethylenediaminetetraacetic acid: 1.6 mg/mL), and the combination of nisin (10,000 IU/mL) with EDTA 1.6 mg/mL either in brain-heart-infusion (BHI) media at 37°C for 72 h or in soy-protein edible coating on the surface of full-fat commercial turkey frankfurters against the cell populations of approximately 106 colony forming units (CFU/mL) of L. monocytogenes. The surface-inoculated frankfurters were dipped into soy-protein film forming solutions with and without the addition of antimicrobial agents [(nisin (10,000 IU) or EDTA (0.16%) or the combination)] and stored at either 4°C or 10°C. The inhibitory effects of edible coatings were evaluated on a weekly basis for 45 d. The greatest inhibitory activities of 6 log cycle reductions of L. monocytogenes were found when nisin was combined with EDTA and eliminated 6 log cycles of L. monocytogenes in both systems. In the combined nisin (10,000 IU) with EDTA (0.16%) treatment, the L. monocytogenes population was reduced to undetectable levels after 15 h or 7 d incubation in BHI at 37°C or on turkey frankfurters stored at 4°C and 10°C, respectively. This research has demonstrated that the use of an edible film coating containing nisin with EDTA is a promising means of controlling the growth and recontamination of L. monocytogenes on RTE meat products

Evaluation of Physicochemical and Antioxidant Properties of Peanut Protein Hydrolysate

Peanut protein and its hydrolysate were compared with a view to their use as food additives. The effects of pH, temperature and protein concentration on some of their key physicochemical properties were investigated. Compared with peanut protein, peanut peptides exhibited a significantly higher solubility and significantly lower turbidity at pH values 2–12 and temperature between 30 and 80°C. Peanut peptide showed better emulsifying capacity, foam capacity and foam stability, but had lower water holding and fat adsorption capacities over a wide range of protein concentrations (2–5 g/100 ml) than peanut protein isolate. In addition, peanut peptide exhibited in vitro antioxidant properties measured in terms of reducing power, scavenging of hydroxyl radical, and scavenging of DPPH radical. These results suggest that peanut peptide appeared to have better functional and antioxidant properties and hence has a good potential as a food additive

Colorants in Cheese Manufacture: Production, Chemistry, Interactions, and Regulation

Colored Cheddar cheeses are prepared by adding an aqueous annatto extract (norbixin) to cheese milk; however, a considerable proportion (∼20%) of such colorant is transferred to whey, which can limit the end use applications of whey products. Different geographical regions have adopted various strategies for handling whey derived from colored cheeses production. For example, in the United States, whey products are treated with oxidizing agents such as hydrogen peroxide and benzoyl peroxide to obtain white and colorless spray‐dried products; however, chemical bleaching of whey is prohibited in Europe and China. Fundamental studies have focused on understanding the interactions between colorants molecules and various components of cheese. In addition, the selective delivery of colorants to the cheese curd through approaches such as encapsulated norbixin and microcapsules of bixin or use of alternative colorants, including fat‐soluble/emulsified versions of annatto or beta‐carotene, has been studied. This review provides a critical analysis of pertinent scientific and patent literature pertaining to colorant delivery in cheese and various types of colorant products on the market for cheese manufacture, and also considers interactions between colorant molecules and cheese components; various strategies for elimination of color transfer to whey during cheese manufacture are also discussed

Agricultural Processing and Utilization Research

In this article, the authors review briefly some of the utilization research work that has been conducted by faculty and staff of the Department of Cereal Science and Food Technology and some of the research in progress or being planned in many areas of agricultural products

Effect of Xanthan Gum on Enhancing the Foaming Properties of Whey Protein Isolate

ABSTRACT: The foaming properties of whey protein isolate (WPI) in the presence of xanthan gum (XG) were investigated. XG dispersion did not exhibit any foaming properties. The optimal foaming overrun (FO), or the amount of air incorporated into the dispersion, was obtained from the dispersion of 5% WPI and 0.05% XG at 949%. This WPI-XG dispersion had a significantly higher overrun than that of WPI (868%) or egg white (879%) (P < 0.05). Optimal foam stability (FS) of 216 min was obtained at 5% WPI and 0.2% XG; however, the overrun was reduced slightly (844%). XG increased stability to 15 times that of WPI alone. The overrun of 5% WPI plus 0.05% XG was further increased to 1343% when 1 M NaCl was added (P < 0.05). However, FS (51 min) was significantly reduced. A significant increase in the FO of 5% WPI plus 0.05% XG (1081%) was observed when pH was adjusted to 5.0 with no significant change in FS (56 min) (P < 0.05). The FO (1457%) was significantly increased (P < 0.05) when the WPI-XG was heat treated (55°C for 5 min). WPI-XG dispersions at acidic pH and temperatures below 85°C have a variety of potential applications in products such as protein beverages, angel food cake, and unique infant formulas. Paper no. J9177 in JAOCS 76, 1383-1386 (November 1999). KEY WORDS: Foam overrun, foam stability, whey protein isolate, xanthan gum. The utilization of whey protein in food products has been limited primarily by the protein's functional properties (1). A decade ago, annual cheese whey production was predicted to exceed 23 × 10 9 kg in the near future. Approximately 60% of this total at that time was being used in yogurt, ice creams, soft drinks, bread, infant foods, and animal feeds (2). However, the remaining 40% created, and still creates, a disposal problem. The limited utilization of whey results in a loss of potential food energy as well as a major economic burden. Whey is a potential source of functional protein that can be used as an emulsifier, a freeze-thaw stabilizer, a whitening agent, or flavor enhancer (2). The use of whey protein as an emulsifier for foams is limited because of poor stability. Efficient foam overrun (FO) requires a foaming agent with flexible molecules and few secondary or tertiary structures, whereas intermolecular cohesiveness and elasticity are required for efficient foam stability (FS) (3). In addition to these intrinsic properties, extrinsic factors such as pH, temperature, and ionic strength affect overrun and stability. Anionic polysaccharides improve the FS of protein dispersions (4). Xie and Hettiarachchy (4) used xanthan gum (XG) to improve the FS of soy protein isolate. XG has been used as a stabilizer, thickener, and foam enhancer (5). XG is widely used as a food gum because its addition causes no discernible change in viscosity within a temperature range of 0 to 100°C. This functionality property makes xanthan unique among gums (6,7). Phillips et al. (8) investigated the effects of heat and pH on the foaming of whey protein isolate (WPI). They found the maximum overrun of 1241% at pH 5.0 with a stability of 40 min. Heat had an effect dependent on pH. At neutral pH, mild heat treatment (55°C) enhanced overrun. More severe heat (80°C) enhanced overrun at a pH less than 5.0. The objectives of this study were to investigate the synergistic effects of WPI and XG on foaming properites (i.e., overrun and FS), and the effects of pH, salt, and heat treatment on WPI-XG. Preparation of WPI-XG dispersions. The WPI-XG dispersions were prepared by mixing WPI and XG in 100 mL 0.05 M sodium phosphate buffer. The dispersions were stirred with a magnetic stirrer (Mistral Pyro Multi-Stirrer, Lab-Line Instruments, Inc., Melrose Park, IL) for 60 min at ambient temperature. They were then used to determine viscosity and foaming properties. Based on preliminary foaming results, 5.0% WPI with 0.05% XG produced optimal foaming properties and was therefore chosen to evaluate the effect of pH and salt treatments. MATERIALS AND METHODS Materials Determination of viscosity. The viscosity of the prepared WPI-XG dispersions in 0.05 M sodium phosphate buffer (pH 7.4) was measured by a Brookfield viscometer (Stoughton, MA). All the measurements were carried out at ambient temperature. Determination of foaming properties. FO of WPI-XG dispersions at varying amounts of whey, gum, and egg white wa