Results from the monitoring of pesticide residues in fruit and vegetables on the Danish market, 2000-01

To check compliance with the maximum residue levels in foods and to monitor the residue levels to enable an evaluation of the exposure of the Danish population to pesticides, a monitoring programme for pesticides residues in fruit and vegetables was performed. Sampling plans were designed based on previous findings and on consumption data. Samples (n = 4404) of mainly fresh conventionally and organically grown fruit and vegetables were collected at wholesalers and importers and at food processing companies. Of the samples, 3% were frozen products and 5% organically grown. Of the samples, 34% were of Danish origin, with 66% from other countries. Two accredited laboratories performed analyses of the samples using capillary gas chromatography, liquid chromatography and a spectrophotometric method. Reporting levels were set at the lowest calibration level or at the limit of determination. Residues were found in 60% of the samples of fruit but in only 18% of the vegetable samples. Residues above the maximum residue levels were found in 6% of all samples of fruit and in 2% of the vegetable samples.     

Enzymatic Firming of Processed Red Pepper by Means of Exogenous Pectinesterase

The objective of this investigation was to demonstrate that the firmness of a commercial vegetable product, diced and frozen red pepper (Capsicum annum var. Sendt), could be improved by the use of exogenous pectinesterase in an industrially relevant process. The diced pepper pieces 10 × 10 × 7 mm³ were infused under vacuum with a commercially available pectinesterase. The range of optimal process conditions was: 15-20°C, 45 min infusion time, a 10-25 mM CaCl₂ infusion brine, a w/w ratio of pepper fruit to infusion brine of 1.5:1, and an enzyme dosage of 30-60 pectinesterase units (PEU) per kg pepper fruit. The firmness as measured by back extrusion was improved by a factor of two to three. The effect of firming was robust and conserved after freezing and heating in a simulated household cooking process. The firming process seems easily adaptable to industrial conditions and may be applicable to other vegetable and fruit products.     

Consumer categorization of plant-based dishes: Implications for promoting vegetable consumption

Strategies to increase vegetable consumption that go beyond their health benefits and the recommendation to consume a specific number of portions a day are necessary. In this sense, a more in-depth understanding of what consumers consider as “vegetables” is of interest, as it can highlight possible mismatches between guidelines and everyday experiences and contribute to the design of public campaigns and interventions. In this context, the aim of the study were: to explore how the plant-based dish category is represented for consumers, to evaluate differences among consumers with different familiarity towards vegetables, to identify the sensory properties that drive typicality and expected liking, and to investigate the relationship between typicality of the dishes and their expected liking and sensory characteristics. One hundred and twenty three consumers were considered for the study. Consumers were characterized for their level of familiarity toward vegetables and pulses and through two psycho-attitudinal questionnaires: Food Neophobia Scale and Health and Taste Attitudes Questionnaire. A total of 80 pictures of plant-based dishes were evaluated to assess the expected liking, healthiness and preparation level of each dish. Consumers were asked to rate and the typicality of the dishes by rating their agreement with the sentence “This is a plant-based dish”. In addition, the sensory properties characterizing each dish were evaluated using Check-All-That-Apply question. Results indicated a graded structure of the plant-based dish category, with some category members more typical than others. Specific recipe typologies, such as salads and boiled vegetables, were perceived as more typical than others, such as soups and fried vegetables. Expected sensory attributes were found to influence the typicality of a dish. The attributes Bitter, Green, Not very intense flavor, Orange, Sour and Watery positively influenced typicality, while Brown and Creamy negatively influenced it. Typicality affected expected liking for the dishes but its influence depended on consumers’ level of familiarity toward vegetables and pulses. In fact, among consumers with a low level of familiarity, the lower the typicality, the higher the expected liking. A less strong association was found among consumers with a high level of familiarity. These results stress that promotion of vegetable consumption targeted to vegetables dislikers should therefore consider their representation of the category, in order to limit the exposure to features with a negative hedonic value.     

Edible films and coatings to prevent the detrimental effect of oxygen on food quality: Possibilities and limitations

Oxygen has a deleterious effect on the quality of a wide variety of food products. The application of edible films and coatings to food products represents a new approach to solve this problem. Edible films and coatings can include antioxidant agents in their formulation and at the same time, they represent a barrier to oxygen, which results in a better preservation of quality. The water activity of the product, as well as the ambient relative humidity, determines the antioxidant effect of films and coatings. This paper reviews the latest studies dealing with the effectiveness and application of antioxidant films and coatings.     

Detection of the residues of nineteen pesticides in fresh vegetable samples using gas chromatography–mass spectrometry

In this study, we investigated the presence of 19 different agricultural pesticides in 210 samples of eight types of domestic vegetables collected from several vegetable-growing regions in Bangladesh. A multiresidue method was developed to detect the pesticide levels in the collected samples using gas chromatography with mass spectrophotometry (GC–MS). Pesticide residues were detected in 51.30% of the total samples, and among the positive samples, 38.89% contained levels above the maximum residue levels (MRLs). The most frequently detected pesticides were chlorpyrifos (34) followed by carbofuran (17), diazinon (16), carbaryl (14), malathion (11), endosulfan (8), cypermethrin (7) and dimethoate (6). Some (10.47%) of the samples contained multiple residues. It is concluded that the continuous monitoring and strict regulation of pesticide use on food crops, especially vegetables, are necessary.     

How neutral coloured backgrounds affect the attractiveness and expensiveness of fresh produce

The colour of the background on which products are presented may affect their perceived attractiveness. In order to find out on which type of background various fresh food products look most attractive, we presented five different vegetables (tomato, carrot, yellow bell pepper, eggplant, mushroom) on five different backgrounds with neutral grey colours varying in degree of blackness: 5, 30, 50, 65, and 90%. Forty-six participants provided colour matches for the vegetables and evaluated them on 10 attributes.Overall, the blackness of the backgrounds had little or no effect on the perceived colour of the vegetable. Only for carrots we found a small but significant difference, mainly between the 5% and 90% blackness backgrounds. On the darkest background, the carrot would be perceived as a bit lighter, more saturated, and more yellow rather than red, compared to the lightest background.Differences in perceived attractiveness on the grey backgrounds varied between 0.3 and 1.0 units on a 9-point scale. Attractiveness and expensiveness ratings for most vegetables were highest on the 90% blackness background. In comparison to our previous study where we presented vegetables on hued backgrounds, differences between mean attractiveness ratings were smaller. Because mean attractiveness ratings in the current study were higher, we expect that grey backgrounds are more likely to present vegetable assortments with a variety of hues in an attractive way than hued backgrounds.     

Model of vegetable freshness perception using luminance cues

Freshness perception is a quality discrimination process that influences our consumer choice and eating behavior, especially of highly perishable products such as vegetables. Previous research used photographic stimuli to investigate the relationship between luminance distribution and freshness perception for a cabbage leaf (C. Arce-Lopera, Masuda, Kimura, et al., 2013) and a strawberry (Carlos Arce-Lopera, Masuda, Kimura, Wada, & Okajima, 2012). In this study, the luminance and chromatic information of the freshness degradation process of four different vegetables (cabbage, strawberry, carrot and spinach) was recorded in a temperature, humidity and light controlled environment. However, instead of a camera, a 2D luminance and chromaticity analyzer (TOPCON UA1000) was chosen as the measurement equipment. Then, using a color management system to guarantee the exact reproduction of the recorded luminance and chromatic data of the real objects, a color and a grayscale version of the stimuli was created. Subsequently, those pictures were randomly presented to subjects who had to rate their perceived freshness using a visual analog scale. The achromatic results did not differ from the chromatic ones suggesting that luminance information is sufficient to enable an accurate estimation of vegetable freshness. Additionally, the original images were digitally manipulated only by modifying their luminance distribution and keeping their color information intact. When the resulting images were presented, using the same psychophysical experimental setting, the results showed that the perceived freshness also changed concordantly with the changes on the asymmetry of the luminance distribution. Finally, a model for vegetable freshness perception that utilizes only luminance cues is presented.     

Results from the monitoring of pesticide residues in fruit and vegetables on the Danish market, 1998?99

The objective of the Danish pesticide monitoring programme for fruit and vegetables was to check for compliance with the maximum residue levels in foods and to monitor the residue levels to assess the pesticide exposure of the Danish population. Sampling plans were designed based on previous findings and on food consumption data. Approximately 60% of the samples were selected on the basis of positive findings in samples from the previous 5 years. The remaining samples reflected the pattern of food consumption in Denmark. In addition, a rolling programme is maintained for commodities with a low consumption and no detected residues. Within each commodity, the sampling was random. Samples (n = 4150) of mainly fresh, conventionally grown fruit and vegetables were taken throughout the chain of suppliers including foodprocessing companies. Of the samples, 3% were frozen products and 2% were organically grown. Of the samples, 35% were of Danish origin, with 65% originating from other countries. Three accredited laboratories performed analyses of the samples using capillary gas chromatography, liquid chromatography and spectrophotometric methods. Results were registered online into a central database. Residues were found in 54% of the samples of fruit but only in 13% of the vegetables. Residues above the MRL were found in 4% of all samples of fruit and in 1% of vegetables.     

Catalytic determination of traces of oxalic acid in vegetables and water samples using a novel optode

A new optode has been introduced for determination of oxalic acid. The optode sensing reagent is Victoria blue 4R which is immobilized on triacetylcellulose membrane. This reagent could be oxidized by dichromate in acidic media resulting in decoloration of the membrane. Oxalic acid has a strong catalytic effect on this reaction. The difference in absorbance of the immobilized form of Victoria blue 4R at 615 nm between uncatalyzed and catalyzed reactions (ΔA) is directly proportional to the concentration of oxalic acid. Oxalic acid can be determined in the concentration range of 2–180 μg ml⁻¹. The effect of different possible interfering species has been examined and was shown that the optode has a very good selectivity. The optode has been applied for the determination of oxalic acid in different real samples such as spinach, beet root, mushroom and river water with excellent recoveries.