Leon A. Terry

1-Methylcyclopropene treatment affects strawberry fruit decay

Strawberry cv. Everest fruit were treated with 1-methylcyclopropene (I-MCP) at various concentrations from 0 to 1000 nl/l for 2 h at 20 degreesC. They were then kept individually in closed but vented containers for 3 days in the dark at 20 degreesC and 95 - 100% relative humidity. 1-MCP treatment tended to maintain strawberry fruit firmness and colour. However. disease development was accelerated in fruit treated at high (500 and 1000 nl/l) I-MCP concentrations. I-MCP treatment also lowered ethylene production. Treatment with I-MCP inhibited phenylalanine ammmonia-lyase (PAL) activity, and lowered increases in anthocyanin and phenolic contents. Comparatively low levels of phenolics in fruit treated at the highest I-MCP concentration (1000 nl/l) could account for decreased disease resistance of these fruit

Biochemical profiling and chemometric analysis of seventeen UK-grown black currant cultivars.

Black currant fruits are recognized as being an important dietary source of health-related compounds, such as anthocyanins and ascorbic acid. In the present study, the biochemical composition (viz., nonstructural carbohydrates, individual anthocyanins, total anthocyanins, total phenolics, and organic acids, including ascorbic acid) from 17 UK-grown black currant cultivars was analyzed. Berry composition was significantly affected by genotype. Nonstructural carbohydrates ranged from 85.09 to 179.92 mg g(-1) on a fresh weight (FW) basis, while concentration for organic acids ranged from 36.56 to 73.35 mg g(-1) FW. Relative concentrations of cyanidin 3-glucoside, cyanidin 3-rutinoside, delphinidin 3-glucoside and delphinidin 3-rutinoside were 3.1-7.9%, 35.4-47.0%, 7.6-12.5% and 36.9-50.9%, respectively. Differences in the biochemical profile among cultivars were emphasized by principal component analysis (PCA) and hierarchical cluster analysis (HCA). PCA was able to discriminate between cultivars, especially on the basis of health-related compounds. Initial exploration revealed that individual anthocyanins, total phenolics, and ascorbic acid could be used to characterize and classify different cultivars. HCA showed that the biochemical composition of the different cultivars was related to parentage information.

Suppression of grey mould on strawberry fruit with the chemical plant activator acibenzolar

Grey mould caused by Botrytis cinerea is the most important post-harvest disease affecting strawberry fruit. This disease is normally controlled by application of fungicides. Increasing public concern over the use of conventional pesticides prompted an investigation as to whether induced systemic acquired resistance (SAR) might be used to help suppress B cinerea on strawberry fruit. Acibenzolar (S-methyl benzo[1,2,3]thiadiazole-7-carbothioate) is a chemical activator of SAR. When applied to strawberry plants at 0.25-2.0 mg AI ml -1 , acibenzolar delayed by about 2 days the development of grey mould disease on harvested strawberry fruit held at 5°C. This delay was equivalent to a 15-20% increase in storage life of the fruit. This preliminary finding suggests that acibenzolar, or perhaps other chemical plant activators, could prove valuable in the commercial management of grey mould on strawberry fruit.

Characterization of Industrial Onion Wastes (Allium cepa L.): Dietary Fibre and Bioactive Compounds

The food industry produces a large amount of onion wastes, making it necessary to search for possible ways for their utilization. One way could be to use these onion wastes as a natural source of high-value functional ingredients, since onion are rich in several groups of compounds, which have perceived benefits to human health. The objective of this work is to gain knowledge of any differences between the different onion wastes obtained from industry and non-commercial bulbs to use them as food ingredients rich in specific compounds. The results showed that brown skin and top–bottom could be potentially used as functional ingredient rich in dietary fibre, mainly in insoluble fraction, and in total phenolics and flavonoids, with high antioxidant activity. Moreover, brown skin showed a high concentration of quercetin aglycone and calcium, and top–bottom showed high concentration of minerals. Outer scales could be used as source of flavonols, with good antioxidant activity and content of dietary fibre. However, inner scales could be an interesting source of fructans and alk(en)yl cystein sulphoxides. In addition, discarded onions (cvs Recas and Figueres) could be used as a good source of dietary fibre, and cv Recas also as a source of phenolics compounds.

A New Palladium-Based Ethylene Scavenger to Control Ethylene-Induced Ripening of Climacteric Fruit

A novel palladium-promoted zeolite material with a significant ethylene adsorption capacity at room temperature is described. It was characterised by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and transmission electron microscopy (TEM) to show palladium particles dispersed over the support. Initial measurements of the ethylene adsorption capacity were conducted with a synthetic gas stream at a higher ethylene concentration than would normally be encountered in fruit/vegetable storage, in order to obtain an accelerated testing protocol. Further laboratory-based trials on fruit samples show that the palladiumpromoted zeolite material can be effective as an ethylene scavenger to prolong the shelf-life of fresh fruits.

Spatial and temporal analysis of textural and biochemical changes of imported avocado cv. hass during fruit ripening.

The ripeness degree of climacteric fruits, such as avocado ( Persea americana Mill.), can be correlated with rheological properties. However, there remains little information on not only the postharvest changes in texture of avocado fruit from different origins but also the spatial variation within fruit. In addition, the relationship between changes in texture and composition of fatty acids and major nonstructural carbohydrates (NSCs) of fruit tissue during ripening is unknown. The texture of different horizontally cut slices from individual fruits within a consignment was measured during ripening using a previously unreported technique. The composition of fatty acids and NSCs in fruit mesocarp tissue was determined. The composition of fatty acids and oil and dry matter contents varied significantly according to origin. Significant changes in texture, mannoheptulose and perseitol contents, and linoleic acid percentage were found in avocado fruit flesh during ripening. Spatial variation within fruit was detected in both textural and biochemical characteristics.

Development of a rapid method for the sequential extraction and subsequent quantification of fatty acids and sugars from avocado mesocarp tissue.

Methods devised for oil extraction from avocado (Persea americana Mill.) mesocarp (e.g., Soxhlet) are usually lengthy and require operation at high temperature. Moreover, methods for extracting sugars from avocado tissue (e.g., 80% ethanol, v/v) do not allow for lipids to be easily measured from the same sample. This study describes a new simple method that enabled sequential extraction and subsequent quantification of both fatty acids and sugars from the same avocado mesocarp tissue sample. Freeze-dried mesocarp samples of avocado cv. Hass fruit of different ripening stages were extracted by homogenization with hexane and the oil extracts quantified for fatty acid composition by GC. The resulting filter residues were readily usable for sugar extraction with methanol (62.5%, v/v). For comparison, oil was also extracted using the standard Soxhlet technique and the resulting thimble residue extracted for sugars as before. An additional experiment was carried out whereby filter residues were also extracted using ethanol. Average oil yield using the Soxhlet technique was significantly (P < 0.05) higher than that obtained by homogenization with hexane, although the difference remained very slight, and fatty acid profiles of the oil extracts following both methods were very similar. Oil recovery improved with increasing ripeness of the fruit with minor differences observed in the fatty acid composition during postharvest ripening. After lipid removal, methanolic extraction was superior in recovering sucrose and perseitol as compared to 80% ethanol (v/v), whereas mannoheptulose recovery was not affected by solvent used. The method presented has the benefits of shorter extraction time, lower extraction temperature, and reduced amount of solvent and can be used for sequential extraction of fatty acids and sugars from the same sample.

Priority research questions for the UK food system

The rise of food security up international political, societal and academic agendas has led to increasing interest in novel means of improving primary food production and reducing waste. There are however, also many ‘post-farm gate’ activities that are critical to food security, including processing, packaging, distributing, retailing, cooking and consuming. These activities all affect a range of important food security elements, notably availability, affordability and other aspects of access, nutrition and safety. Addressing the challenge of universal food security, in the context of a number of other policy goals (e.g. social, economic and environmental sustainability), is of keen interest to a range of UK stakeholders but requires an up-to-date evidence base and continuous innovation. An exercise was therefore conducted, under the auspices of the UK Global Food Security Programme, to identify priority research questions with a focus on the UK food system (though the outcomes may be broadly applicable to other developed nations). Emphasis was placed on incorporating a wide range of perspectives (‘world views’) from different stakeholder groups: policy, private sector, non-governmental organisations, advocacy groups and academia. A total of 456 individuals submitted 820 questions from which 100 were selected by a process of online voting and a three-stage workshop voting exercise. These 100 final questions were sorted into 10 themes and the ‘top’ question for each theme identified by a further voting exercise. This step also allowed four different stakeholder groups to select the top 7–8 questions from their perspectives. Results of these voting exercises are presented. It is clear from the wide range of questions prioritised in this exercise that the different stakeholder groups identified specific research needs on a range of post-farm gate activities and food security outcomes. Evidence needs related to food affordability, nutrition and food safety (all key elements of food security) featured highly in the exercise. While there were some questions relating to climate impacts on production, other important topics for food security (e.g. trade, transport, preference and cultural needs) were not viewed as strongly by the participants.

A new acetonitrile-free mobile phase method for LC–ELSD quantification of fructooligosaccharides in onion (Allium cepa L.)

Onion soluble non-structural carbohydrates consist of fructose, glucose and sucrose plus fructooligosaccharides (FOS) with degrees of polymerisation (DP) in the range of 3-19. In onion, sugars and FOS are typically separated using liquid chromatography (LC) with acetonitrile (ACN) as a mobile phase. In recent times, however, the production of ACN has diminished due, in part, to the current worldwide economic recession. A study was therefore undertaken, to find an alternative LC method to quantify sugars and FOS from onion without the need for ACN. Two mobile phases were compared; the first taken from a paper by Vågen and Slimestad (2008) using ACN mobile phase, the second, a newly reported method using ethanol (EtOH). The EtOH mobile phase eluted similar concentrations of all FOS compared to the ACN mobile phase. In addition, limit of detection, limit of quantification and relative standard deviation values were sufficiently and consistently lower for all FOS using the EtOH mobile phase. The drawback of the EtOH mobile phase was mainly the inability to separate all individual sugar peaks, yet FOS could be successfully separated. However, using the same onion extract, a previously established LC method based on an isocratic water mobile phase could be used in a second run to separate sugars. Although the ACN mobile phase method is more convenient, in the current economic climate a method based on inexpensive and plentiful ethanol is a valid alternative and could potentially be applied to other fresh produce types. In addition to the mobile phase solvent, the effect of extraction solvents on sugar and FOS concentration was also investigated. EtOH is still widely used to extract sugars from onion although previous literature has concluded that MeOH is a superior solvent. For this reason, an EtOH-based extraction method was compared with a MeOH-based method to extract both sugars and FOS. The MeOH-based extraction method was more efficacious at extracting sugars and FOS from onion flesh, eluting significantly higher concentrations of glucose, kestose, nystose and DP5-DP8.

A new acetonitrile-free mobile phase for HPLC-DAD determination of individual anthocyanins in blackcurrant and strawberry fruits: A comparison and validation study

Research focused on identification and quantification of anthocyanins from berries and other fruits is gaining importance due to the observed inverse relationship between anthocyanin intake and the incidence of certain diseases. Separation and quantification of these compounds is mainly achieved on reverse phase HPLC coupled to different detection systems using mostly acetonitrile as the mobile phase of choice. Nevertheless, the scientific community recently faced a worldwide shortage of this solvent which resulted in prices soaring dramatically. In this context, the present study describes the comparison and validation of a newly developed methanol-based method for the identification and quantification of major berry anthocyanins using standard HPLC coupled to photo diode array detection. Moreover, two different commercially available stationary phases were tested. The methanol-based method developed herein showed high repeatability (R.S.D <1.3%), rapidity (<35min) and accuracy and therefore may be suitable for routine quantification of berry anthocyanins. Comparison with an earlier established acetonitrile-based method showed that despite differences in absolute concentrations between both methods the determined anthocyanin concentrations were highly correlated (r>0.95). Method validation was further achieved by elucidating differences in the anthocyanin profile between different blackcurrant and strawberry cultivars.