Improving functional properties of pea protein isolate for microencapsulation of flaxseed oil

Unhydrolysed pea protein (UN) forms very viscous emulsions when used at higher concentrations. To overcome this, UN was hydrolysed using enzymes alcalase, flavourzyme, neutrase, alcalase-flavourzyme, and neutrase-flavourzyme at 50 °C for 0 min, 30 min, 60 min, and 120 min to form hydrolysed proteins A, F, N, AF, and NF, respectively. All hydrolysed proteins had lower apparent viscosity and higher solubility than UN. Foaming capacity of A was the highest, followed by NF, N, and AF. Hydrolysed proteins N60, A60, NF60, and AF60 were prepared by hydrolysing UN for 60 min and used further for microencapsulation. At 20% oil loading (on a total solid basis), the encapsulated powder N60 had the highest microencapsulation efficiency (ME = 56.2). A decrease in ME occurred as oil loading increased to 40%. To improve the ME of N60, >90%, UN and maltodextrin were added. Flowability and particle size distribution of microencapsulated powders with >90% microencapsulation efficiency and morphology of all powders were investigated. This study identified a new way to improve pea protein functionality in emulsions, as well as a new application of hydrolysed pea protein as wall material for microencapsulation.

Oxidation-reduction potential and lipid oxidation in ready-to-eat blue mussels in red sauce: criteria for package design

BACKGROUND

Ready-to-eat in-package pasteurized blue mussels in red sauce requires refrigerated storage or in combination with an aerobic environment to prevent the growth of anaerobes. A low barrier packaging may create an aerobic environment; however, it causes lipid oxidation in mussels. Thus, evaluation of the oxidation-reduction potential (Eh) (aerobic/anaerobic nature of food) and lipid oxidation is essential. Three packaging materials with oxygen transmission rate (OTR) of 62 (F-62), 40 (F-40) and 3 (F-3) cm³ m^-2 day^-1 were selected for this study. Lipid oxidation was measured by color changes in thiobarbituric acid reactive substances (TBARS) at 532 nm (TBARS@532) and 450 nm (TBARS@450).

RESULTS

Significantly higher (P < 0.05) TBARS@532 was found in mussels packaged in higher OTR film. TBARS@450 in mussels packaged with F-62 and F-40 gradually increased during refrigerated storage (3.5 ± 0.5 °C), but remained constant after 20 days of storage for mussels packaged with F-3. The Eh of pasteurized sauce was not significantly affected (P > 0.05) by OTR and remained negative (< -80 mV) during storage. Negative Eh values can support the growth of anaerobes such as Clostridium botulinum. The headspace oxygen concentration was reduced by about 50% from its initial value during pasteurization, and then further declined during storage. The headspace oxygen concentration was higher in trays packaged with higher OTR film.

CONCLUSION

Mussels packed with high OTR film showed higher lipid oxidation, indicating that high barrier film is required for packaging of mussels. Pasteurized mussels must be kept in refrigerated storage to prevent growth of anaerobic proteolytic C. botulinum spores under temperature abuse. © 2016 Society of Chemical Industry.

Ultraviolet-C Light Sanitization of English Cucumber (Cucumis sativus) Packaged in Polyethylene Film

Food safety is becoming an increasing concern in the United States. This study investigated the effects of ultraviolet-C (UV-C) light as a postpackaging bactericidal treatment on the quality of English cucumber packaged in polyethylene (PE) film. Escherichia coli k-12 was used as a surrogate microbe. The microbial growth and physical properties of packaged cucumbers were analyzed during a 28-d storage period at 5 °C. Inoculating packaged cucumbers treated at 23 °C for 6 min with UV-C (560 mJ/cm(2) ) resulted in a 1.60 log CFU/g reduction. However, this treatment had no significant effect (P > 0.05) on the water vapor transmission rate or oxygen transmission rate of the PE film. Results show that UV-C light treatment delayed the loss of firmness and yellowing of English cucumber up to 28 d at 5 °C. In addition, UV-C light treatment extended the shelf life of treated cucumber 1 wk longer compared to untreated cucumbers. Electron microscopy images indicate that UV-C light treatment influences the morphology of the E. coli k-12 cells. Findings demonstrate that treating cucumbers with UV-C light following packaging in PE film can reduce bacterial populations significantly and delay quality loss. This technology may also be effective for other similarly packaged fresh fruits and vegetables.

Sodium Chloride Diffusion in Low-Acid Foods during Thermal Processing and Storage

This study aimed at modeling sodium chloride (NaCl) diffusion in foods during thermal processing using analytical and numerical solutions and at investigating the changes in NaCl concentrations during storage after processing. Potato, radish, and salmon samples in 1% or 3% NaCl solutions were heated at 90, 105, or 121 °C for 5 to 240 min to simulate pasteurization and sterilization. Selected samples were stored at 4 or 22 °C for up to 28 d. Radish had the largest equilibrium NaCl concentrations and equilibrium distribution coefficients, but smallest effective diffusion coefficients, indicating that a greater amount of NaCl diffused into the radish at a slower rate. Effective diffusion coefficients determined using the analytical solution ranged from 0.2 × 10(-8) to 2.6 × 10(-8) m²/s. Numerical and analytical solutions showed good agreement with experimental data, with average coefficients of determination for samples in 1% NaCl at 121 °C of 0.98 and 0.95, respectively. During storage, food samples equilibrated to a similar NaCl concentration regardless of the thermal processing severity. The results suggest that sensory evaluation of multiphase (solid and liquid) products should occur at least 14 d after processing to allow enough time for the salt to equilibrate within the product.

Effect of oxygen stress on growth and survival of Clostridium perfringens, Campylobacter jejuni, and Listeria monocytogenes under different storage conditions

This study investigated the growth and survival of three foodborne pathogens (Clostridium perfringens, Campylobacter jejuni, and Listeria monocytogenes) in beef (7% fat) and nutrient broth under different oxygen levels. Samples were tested under anoxic (<0.5%), microoxic (6 to 8%), and oxic (20%) conditions during storage at 7 °C for 14 days and at 22 °C for 5 days. Two initial inoculum concentrations were used (1 and 2 log CFU per g of beef or per ml of broth). The results show that C. perfringens could grow in beef at 22 °C, with an increase of approximately 5 log under anoxic conditions and a 1-log increase under microoxic conditions. However, C. perfringens could not survive in beef held at 7 °C under microoxic and oxic storage conditions after 14 days. In an anoxic environment, C. perfringens survived in beef samples held at 7 °C, with a 1-log reduction. A cell decline was observed at 2 log under these conditions, with no surviving cells at the 1-log level. However, the results show that C. jejuni under microoxic conditions survived with declining cell numbers. Significant increases in L. monocytogenes (5 to 7 log) were observed in beef held at 22 °C for 5 days, with the lowest levels recovered under anoxic conditions. L. monocytogenes in refrigerated storage increased by a factor of 2 to 4 log. It showed the greatest growth under oxic conditions, with significant growth under anoxic conditions. These findings can be used to enhance food safety in vacuum-packed and modified atmosphere-packaged food products.

Selective esterification to produce microalgal biodiesel and enrich polyunsaturated fatty acid using zeolite as a catalyst

A novel integrated process to produce microalgal biodiesel and simultaneously enrich high-value polyunsaturated fatty acids (PUFA) using selective catalyst.

Engineered nanoparticle adhesion and removal from tomato surfaces

Engineered nanoparticles (NPs) are being used in different industries due to their unique physicochemical properties. NPs may be toxic and could pose both public health and environmental contamination risks. In this study, two concentrations (50 and 500 μg mL(-1)) of titania (TiO2), silica (SiO2), and alumina (Al2O3) were applied to contaminate the surface of cherry tomato as a food model, followed by washing with deionized water (DI) to remove the NPs from the tomato surfaces. The NP surface charge and hydrodynamic diameter results showed that the isoelectric point (IEP) for alumina was at pH 9-9.6, for silica at pH <3, and for titania was at pH 6.5-6.8; in addition, the highest hydrodynamic size for all NPs was observed at the IEP. Inductively coupled plasma mass spectrometry (ICP-MS) indicated that the highest NP concentration was observed on tomato surfaces contaminated at the higher concentration (500 μg mL(-1)) (P < 0.05). After the tomatoes had been washed with DI, alumina levels decreased significantly, whereas for titania and silica, no significant difference in NP concentration on tomato surface was observed following the washing treatment. This study shows that removal of NPs may be possible with a simple washing treatment but that removal of NPs is likely to be more effective when the moment ratio is >1, which can occur if the pH of the washing solution is significantly different from the IEP of NPs.

Predicting the Quality of Pasteurized Vegetables Using Kinetic Models: A Review

A resurgence in interest examining thermal pasteurization technologies has been driven by demands for "cleaner" labeling and the need of organic and natural foods markets for suitable preventive measures to impede microbial growth and extend shelf life of minimally processed foods and ready-to-eat foods with a concomitant reduction in the use of chemical preservatives. This review describes the effects of thermal pasteurization on vegetable quality attributes including altering flavor and texture to improve consumer acceptability, stabilizing color, improving digestibility, palatability and retaining bioavailability of important nutrients, and bioactive compounds. Here, we provide kinetic parameters for inactivation of viral and bacterial pathogens and their surrogates and marker enzymes used to monitor process effectiveness in a variety of plant food items. Data on thermal processing protocols leading to higher retention and bioactivity are also presented. Thermal inactivation of foodborne viruses and pathogenic bacteria, specifically at lower pasteurization temperatures or via new technologies such as dielectric heating, can lead to greater retention of "fresh-like" properties.