J. Van Camp

The use of high pressure to modify the functionality of food proteins

High pressure (up to 1000 MPa) can affect protein conformation and can lead to protein denaturation, aggregation or gelation, depending on the protein system, the applied pressure, the temperature and the duration of the pressure treatment. Although the effects of pressure on proteins have already been studied for several decades, applied research on the application of high pressure to induce the denaturation, aggregation and gelation of food proteins did not become of significant interest until the late 1980s. Studies that have been published in this area are reviewed, and the potential applications and limitations of high-pressure technology are highlighted.

Eating out of home and its association with dietary intake: a systematic review of the evidence

During the last decades, eating out of home (OH) has gained importance in the diets worldwide. We document the nutritional characteristics of eating OH and its associations with energy intake, dietary quality and socioeconomic status. We carried out a systematic review of peer‐reviewed studies in eight databases up to 10 March 2011. Of the 7,319 studies retrieved, 29 met the inclusion criteria and were analysed in this review. The quality of the data was assessed and a sensitivity analysis was conducted by isolating nationally representative or large cohort data from 6 and 11 countries, respectively. OH foods were important sources of energy in all age groups and their energy contribution increased in adolescents and young adults. Eating OH was associated with a higher total energy intake, energy contribution from fat in the daily diet and higher socioeconomic status. Two large studies showed how eating OH was also associated with a lower intake of micronutrients, particularly vitamin C, Ca and Fe. Although the studies were cross‐sectional and heterogeneous in the way they classified eating OH, we conclude that eating OH is a risk factor for higher energy and fat intake and lower micronutrient intake.

Co-occurrence of fumonisins with aflatoxins in home-stored maize for human consumption in rural villages of Tanzania.

This study determined maize-user practices that influence the presence of fumonisin and aflatoxin contamination of maize in food consumed in the rural areas of Tanzania. Samples of the 2005 maize harvest in Tanzania were collected from 120 households and examined for fumonisins and aflatoxins. Information on whether the maize was sorted to remove defective (visibly damaged or mouldy) maize before storage and whether the damaged and mouldy maize or the non-dehulled maize was used as food was also collected. In addition, the percentage of defective kernels in the samples was determined. Ninety per cent of the households sorted out defective maize, 45% consumed the defective maize and 30% consumed non-dehulled maize. In 52% of the samples fumonisins were determined at levels up to 11,048 µg kg−1 (median = 363 µg kg−1) and in 15% exceeded 1000 µg kg−1; the maximum tolerable limit (MTL) for fumonisins in maize for human consumption in other countries. Aflatoxins were detected in 18% of the samples at levels up to 158 µg kg−1 (median = 24 µg kg−1). Twelve per cent of the samples exceeded the Tanzanian limit for total aflatoxins (10 µg kg−1). Aflatoxins co-occurred with fumonisins in 10% of the samples. The percentage defective kernels (mean = 22%) correlated positively (r = 0.39) with the fumonisin levels. Tanzanians are at a risk of exposure to fumonisins and aflatoxins in maize. There is a need for further research on fumonisin and aflatoxin exposure in Tanzania to develop appropriate control strategies.

High pressure-induced gel formation of a whey protein and haemoglobin protein concentrate

High pressure-induced gel formation of whey protein concentrate (WPC), egg white concentrate (EWC), blood plasma concentrate (BPC), and haemoglobin protein concentrate (HPC), was studied at operating pressures up to 4 kbar without additional supply of heat to the pressure vessel. High pressure (4 kbar: 30 min) generated weaker gel networks for WPC and HPC compared to heat set gels (80°C: 30 min) at a given protein concentration of 90 to 180 g/L for WPC, and 80 to 140 g/L for HPC. A minimum operating pressure of 2 kbar for WPC and 3 kbar for HPC, combined with a minimum protein concentration of 160 and 120 g/L respectively, were necessary for network formation to occur. Longer durations generated stronger gel networks, while the effects of repeated compression remained limited. For WPC, only strong high pressure-induced gels were formed in the alkaline pH region. Pressure-sensitive buffer salts (e.g. phosphate) reduced the strength of high pressure-induced WPC gels, presumably caused by lowering the pH under pressure. For BPC and EWC, which easily form heat set gels, no visual gel formation occurred after a pressure treatment of 30 min at 4 kbar.

A comparative rheological study of heat and high pressure induced whey protein gels

Abstract The rheological properties of whey protein concentrate (WPC) gels induced by high pressure (4000 bar/30 min), were compared to those induced by heat (80 °C/30 min) at protein concentrations ranging from 110 up to 183 g/liter. Oscillation measurements at 1 Hz and 0.001 strain showed the highest storage and loss moduli for heat set gels, while creep experiments at a stress level of 40 Pa gave larger sample deformations for high pressure induced gels. Relaxation experiments performed at 17 and 33% deformation were characterized by a higher force decay as a function of time for the high pressure gels, while during compression the compression modulus was always higher in the case of heat set gels. Electron microscopy showed a higher level of cross links in the heat induced gels; high pressure generated a more porous network with a lower amount of intermolecular cross links.

A concise overview of national nutrition action plans in the European Union Member States

OBJECTIVE This study presents an overview of national nutrition action plans in the member states of the European Union (EU), before its enlargement in 2004. In addition, their compliance with key recommendations of the World Health Organization, as documented in the First Action Plan for Food and Nutrition Policy and the Global Strategy on Diet, Physical Activity and Health, has tentatively been evaluated on the basis of the policy documents published. DESIGN Literature review of publicly available policy national plans on nutrition and physical activity. SETTING Member states of the EU before enlargement in May 2004. RESULTS The development of national nutrition action plans is gaining momentum. Six of the 15 EU member states - namely, Sweden, Finland, Denmark, France, The Netherlands and the UK - have an operational nutrition policy and four of them have published an elaborated description of their nutrition policy in English. By the end of 2004, another four countries are expected to have their plan finalised. The available nutrition action plans generally seem to comply with international recommendations, although large variations are observed between the member states in terms of terminology, nutritional recommendations, institutional framework, nutritional scope, social groups targeted and monitoring and evaluation structures. CONCLUSIONS Although the importance of nutritional surveillance, a comprehensive approach to nutritional problems and stakeholder involvement is recognised by the action plans, the justification for it is vaguely described. This paper advocates for proper evaluation and documentation of interventions in public health nutrition and nutrition policies.

Optimization and evaluation of a decontamination step with peroxyacetic acid for fresh-cut produce.

Since several disadvantages are associated with the use of sodium hypochlorite as a decontamination agent, the attention for alternative agents such as peroxyacetic acid (PAA) is increasing. In this study the effectiveness of PAA to remove the native microflora was tested in four types of fresh-cut vegetables: grated carrots, fresh-cut white cabbage, iceberg lettuce and leek. Furthermore, the influence of varying PAA concentrations (0, 25, 80, 150 and 250 ppm) and varying contact times (1, 5 and 10 min) was described by means of a linear model. The efficiency of PAA to remove the native flora was highly dependent on the type of fresh-cut produce: the highest microbial reductions were obtained for carrots (0.5-3.5 log cfu/g) and white cabbage (0.5-3.5 log cfu/g) followed by iceberg lettuce (0.4-2.4 log cfu/g). The obtained efficiency was the lowest for fresh-cut leek (0.4-1.4 log cfu/g). Furthermore, all the treated samples, regardless of the type of vegetable and the contact time and concentration of the PAA treatment, were acceptable for consumption.

Effects of food composition on the inactivation of foodborne microorganisms by chlorine dioxide.

Chlorine dioxide (ClO2) is a strong oxidizing agent that can be applied in solution as well as in the gaseous state. It has bactericidal, fungicidal and viricidal properties. Several food-related microorganisms, including Gram-negative and Gram-positive bacteria, yeasts, mould spores and Bacillus cereus spores were tested for their susceptibility to 0.08 mg/L gaseous ClO2 during 1 min at a relative humidity of 90%. In this screening, the resistance of the different groups of microorganisms towards gaseous ClO2 generally increased in the order Gram-negative bacteria, Gram-positive bacteria, yeasts and mould spores and Bacillus cereus spores. With this treatment, reductions of microbial numbers between 0.1 and 3.5 log cfu/cm2 could be achieved. The effects of the food components starch, fat, protein and NaCl on the antimicrobial activity of gaseous ClO2 were also evaluated. Soluble starch, corn oil, butter, whey protein isolate and NaCl were added in incremental concentrations to portions of an agar medium. Then, plates of the supplemented agars were inoculated with Leuconostoc mesenteroïdes at numbers of 4 log cfu/cm2 and subsequently treated with ClO2. Both soluble starch and NaCl did not have an effect on the antimicrobial efficiency of ClO2. However, butter, corn oil or whey protein in the agar almost eliminated the antimicrobial effect of ClO2. In corn oil-water emulsions treated with gaseous ClO2 the peroxide value increased significantly, indicating the formation of primary oxidation products. Similarly, a treatment with ClO2 increased the protein carbonyl content and induced the transformation of SH-groups to -S-S-groups in whey protein. The findings suggest that gaseous ClO2 will be a highly effective decontaminating agent for carbohydrate-rich foods, but that it would be less effective for the decontamination of high-protein and fatty foods.

Effect of washing conditions on the recovery of milk fat globule membrane proteins during the isolation of milk fat globule membrane from milk

During the isolation of milk fat globule membrane (MFGM) from milk, washing is considered the most critical stage in which loss of MFGM components occurs. In this study, using a cream separator, the influence of washing on the recovery of MFGM proteins was investigated. The residue of non-MFGM proteins in the MFGM material obtained after washing was quantitatively determined using densitometric analysis of one-dimensional sodium dodecyl sulfate-PAGE after silver staining of the gel. Using deionized water as the washing solution did not increase the loss of MFGM proteins compared with other common salt solutions in terms of recovery of MFGM proteins and contamination with non-MFGM proteins. The increase in wash temperature from 38 to 46 degrees C did not show a significant decrease in yield of MFGM proteins because of variation between the experimental replicates. Coalescence of fat globules occurs during isolation. To increase MFGM purity while maintaining a high MFGM protein recovery, using larger volumes of wash solution is more advisable rather than increasing the number of washings from 2 to 3.

Validity of photographs for food portion estimation in a rural West African setting

OBJECTIVE To validate food photographs for food portion size estimation of frequently consumed dishes, to be used in a 24-hour recall food consumption study of pregnant women in a rural environment in Burkina Faso. This food intake study is part of an intervention evaluating the efficacy of prenatal micronutrient supplementation on birth outcomes. SUBJECTS Women of childbearing age (15-45 years). DESIGN A food photograph album containing four photographs of food portions per food item was compiled for eight selected food items. Subjects were presented two food items each in the morning and two in the afternoon. These foods were weighed to the exact weight of a food depicted in one of the photographs and were in the same receptacles. The next day another fieldworker presented the food photographs to the subjects to test their ability to choose the correct photograph. RESULTS The correct photograph out of the four proposed was chosen in 55% of 1028 estimations. For each food, proportions of underestimating and overestimating participants were balanced, except for rice and couscous. On a group level, mean differences between served and estimated portion sizes were between -8.4% and 6.3%. Subjects who attended school were almost twice as likely to choose the correct photograph. The portion size served (small vs. largest sizes) had a significant influence on the portion estimation ability. CONCLUSIONS The results from this study indicate that in a West African rural setting, food photographs can be a valuable tool for the quantification of food portion size on group level.