Graham A. Bonwick

Evaluation of heat shock protein 70 as a biomarker of environmental stress in Fucus serratus and Lemna minor

Heat shock proteins (Hsps) are known to be induced in response to short-term stress. The present study aimed to evaluate the potential of Hsp70 as a biomarker of stress produced by increased temperature, osmotic pressure, and exposure to cadmium and sodium chloride in marine macroalgae and fresh water plant species. An indirect competitive enzyme-linked immunosorbent assay (IC-ELISA) was developed with a working range of 0.025–10 μg ml−1 using a monoclonal antibody raised against purified Hsp70 of Phaseolus aureus (mung bean). Fucus serratus (toothed wrack), Chondrus crispus (Stackhouse or Carrageen moss), Ulva lactuca (sea lettuce) and Lemna minor (common duckweed) sample extracts were stressed for up to 24 h and then tested in the IC-ELISA. The presence of Hsp70 and cross-reactivity of the monoclonal antibody was confirmed by Western blot. The heat shock response was confirmed in each species using a 2-h 42°C treatment. Following heat shock, Hsp70 concentrations increased to a peak at 2 h (F. serratus) or 4 h (L. minor), after which concentrations decreased. Osmotic and cadmium stresses also resulted in elevated Hsp70 concentrations in samples of F. serratus and L. minor when compared with unstressed controls. In both, osmotic and metal stress, the production of Hsp70 increased to a maximum and subsequently decreased as the stressor levels increased. Results suggest that Hsp70 IC-ELISA could potentially be applied to the detection of stress in these aquatic species, although it would probably be most effective when used in conjunction with other measurements to provide a stressor-specific biomarker profile or fingerprint.

Synchrotron Radiation Macrobeam and Microbeam X-ray Diffraction Studies of Interfacial Crystallization of Fats in Water-in-Oil Emulsions

Using macrobeam and microbeam techniques, we performed synchrotron radiation X-ray diffraction (SR-XRD) analyses of fat crystallization in water-in-oil (W/O) emulsion, in combination with DSC and polarized optical microscopic observation. Particular focus was on the crystallization of the fats around water droplets in the W/O emulsion systems using food emulsifiers of polyglycerol polyricinoleate (PGPR) alone (PGPR emulsion), and PGPR and monobehenoylglycerol (MB) (PGPR+MB emulsion). We obtained the following results: (1) macrobeam SR-XRD confirmed that adding MB promoted fat crystallization during cooling, (2) microbeam SR-XRD indicated that the lamellar planes of fat crystals near the water and oil interfaces are arranged almost parallel to the interface planes in both PGPR emulsion and PGPR+MB emulsion, and (3) adding MB resulted in the formation of tiny fat crystals because it promoted crystallization, which occurred both in the bulk oil phase and at the W/O interfaces. The present study is the first to apply microbeam SR-XRD to observe the microscopic features of fat crystallization in W/O emulsion, following fat crystallization in the oil droplets in the oil-in-water (O/W) emulsion (Arima, S.; Ueno, S.; Ogawa, A.; Sato, K. Langmuir 2009, 25, 9777-9784).

Parents' use and understanding of front-of-pack food labelling, and the impact of socio-economic status

Research has shown that consumers, particularly those of low socio-economic status, find traditional back-of-pack panels to be complex (1,2) The 2004 White Paper has identified the need for a front-of-pack system that allows for informed healthy choices and addresses inequalities in health (3) . Two systems have been most prominently debated; the ‘traffic-light’ (MTL) and ‘guideline daily amount’ (GDA) systems. Research into system effectiveness is limited and inconclusive (4‐10) , but clearly establishes a need to implement a single system. The present study intended to identify (a) the most effective front-of-pack format for parents, (b) format preferences, (c) the formats’ potential for future use and (d) differences across socio-economic groups. Two groups of parents were selected; one from an area of high deprivation (n 53) and one from an area of low deprivation (n 53), recruited through two schools of a similar size (n 212 and n 194, respectively) in the south of Birmingham. Socio-economic status was determined indirectly using census data for the postcode in which the majority of parents attending the schools lived. Indicators included index of multiple deprivation, levels of unemployment, social housing, self-rating of health, educational attainment, as well as numbers accessing free school meals per school. Both quantitative and qualitative methods were utilized. A self-administered parent questionnaire measured current use of front-of-pack labels, understanding of the two systems (through a product-comparison performance test) and format preferences. Statistical analysis was performed. Focus groups were carried out to explore possible barriers to using front-of-pack labels, features leading to preference and likelihood for future use of the systems. Two groups of four to six individuals were carried out per school using a standardized semi-structured discussion guide. Discourse was audio-taped, transcribed and thematically analysed. For both methods of labelling it was requested that the primary shopper within the family should respond in order to ensure that the results held validity amongst the potential label-using population. The results revealed no between-group differences in current use of front-of-pack labelling, although lower socio-economic groups identified more barriers to using them, indicating an ‘at-a-glance’ format might be more relevant to them. Performance tests found that the GDA format best allowed consumers to identify healthy products (mean score 3.08 out of 4 v. 2.79 out of 4; P < 0.01). There was no difference in performance across socio-economic groups. It was established that the MTL system was preferred by all parents for its ease and speed of use, and was also more likely to be used in the future as it is more accessible and attention-grabbing. Although the GDA system was considered informative, it was also thought to be more difficult to use and easy to ignore. In conclusion, the study identified a ‘trade-off’ that may occur in attempting to implement a single system of front-of-pack labelling; between a system that provokes active use but leads to less accurate distinctions between products (MTL), and a system that may be overlooked by parents, but leads to marginally healthier choices (GDA).