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Mineral and nutritional content of produce - HH3720SX

Description
This contract comprises two distinct one-year projects that have been combined within HH35: Sustainable Crop Nutrition. The first project aims to determine if the mineral content of edible horticultural and potato crops is in decline, and the second project aims to determine ways to enhance the gamma-linolenic acid content of blackcurrant seeds. The objective of the first project (to be undertaken at HRI-Wellesbourne) is to investigate the basis of the often-repeated claim that the mineral content of horticultural crops available in the UK has decreased since the 1930s. Various authors have stated explicitly that UK consumers are eating fruit and vegetables of declining quality [1-5]. In their articles, the decrease in the mineral nutrient concentrations in raw fruit and vegetables is attributed to modern breeding and cultural practices. Since these claims are potentially detrimental to the UK horticulture industry, it is important to ascertain their validity. If they prove to be correct, then there are immediate opportunities to improve crop genotypes and cultural practices to ameliorate the problem.The claim that the mineral nutrient concentrations in UK fruit and vegetables are declining will be addressed through a critique of the original articles [1-3] and through a desk based study: (i) to determine if sufficient evidence exists in the literature to test the hypothesis that the mineral composition of raw fruit and vegetables available in the UK has declined since the 1930s, (ii) to test this hypothesis (if possible), (iii) to compare the historical trends in the mineral composition of fruit and vegetables available in the UK with similar data from the USA, whose historical horticultural and consumer practices have paralleled those of the UK, and (iv) to recommend future research options. The objective of the second project (to be undertaken at HRI-East Malling) is to add value to a by-product of blackcurrant processing; seed oil containing gamma-linolenic acid (GLA). This would be of value to the Blackcurrant Growers Association. Evidence from other plant species suggests that environmental manipulation could enhance GLA accumulation and the research will investigate the potential to enhance GLA accumulation in blackcurrant seeds through specific agronomic manipulations. Both projects contribute to the scientific objectives described under HH35 `to improve understanding of the relationships between nutrient supply and the growth, development and production of horticultural crops` and to HH37: `to breed plants with improved nutritional content`. Project 2 also addresses Defra’s interest in adding value to crops through the use of by-products. Project 1 will provide an insight to the historical trends of two aspects of produce quality: (1) mineral contents of edible fruit and vegetables and (2) their post-harvest storage quality, which is critically dependent on mineral content. In addition, since changes in the mineral content of fruit and vegetables are likely to reflect the recovery of fertilisers from soils, the data can be combined with knowledge of the historical trends in fertiliser recommendations to provide an indication of the historical trends in fertiliser use efficiency by horticultural crops. Project 2 follows approach (iii) of HH35 to investigate the interactions between nutrient supply, crop quality and plant growth and development, by examining the influences of various environmental and agronomic factors on the final yield and quality of horticultural produce.Results from these projects will be used to inform horticultural practices and breeding programmes for improved product quality and nutrient-use efficiency. They will be communicated to growers, breeders, policy-makers and the scientific community through targeted technology transfer. The work will complement that undertaken in a Defra-funded project to characterise the genetics of nutrient use efficiency in brassicas (HH3501SFV) and a SEERAD BBSRC-funded HortLINK project to enhance vitamin C content in blackcurrants.

This contract has two distinct one-year projects that have been combined within HH35: Sustainable Crop Nutrition. Various authors have stated explicitly that UK consumers are eating fruit and vegetables of declining quality [1-5]. In their articles, the decrease in the mineral nutrient concentrations in raw fruit and vegetables is attributed to modern breeding and cultural practices. Any claim that the quality of horticultural produce available in the UK is declining is potentially detrimental to the UK horticulture industry. It is, therefore, important to ascertain the validity of such claims. The aims of the first project are threefold: (1) to investigate the scientific basis of the often-repeated claim that the mineral content of horticultural crops available in the UK has decreased since the 1930s [1-5], (2) to test the hypothesis that the mineral content of edible horticultural and potato crops has declined between the 1930s and the present day and, (3) if there is sufficient evidence that the mineral content of horticultural produce has declined, to recommend future research options to determine the impact of contrasting crop genotypes and cultural practices to this phenomenon. The second project aims to add value to by-products of blackcurrant processing by increasing the amount of gamma-linolenic acid (GLA) present in seed oil through agronomic manipulation. GLA is a high value speciality chemical with important therapeutic applications, but is currently under exploited by blackcurrant growers because the quality of the blackcurrant seed oil is not consistent year to year. This project aims to create a new market opportunity for blackcurrant by-products by undertaking research to inform novel agronomic practices that will improve the year-to-year consistency in the GLA content of blackcurrant seeds. This would be of value to the Blackcurrant Growers Associations. This strategic research is beyond the capability of individual growers, and is not yet applicable for HDC funding. In addition to the specific contributions to HH35 and HH37, Project 2 addresses Defra’s interest in adding value to crops through the use of by-products. The associated Defra report states “More needs to be made of by-products generally. Global competition means that it is a much easier step to make use of `waste` rather than grow a crop for a new market which must bear all of the cost”.

It has been repeatedly reported in the food-science literature [1], in promotional materials of companies supplying prophylactic mineral supplements [2,3] and in the popular press [e.g. 4,5] that the mineral concentrations in edible portions of horticultural crops consumed in the UK has decreased since the 1930s. However, these reports appear to be based on limited scientific evidence and may lack statistical rigour. The first project is a desk-based study that will provide a critique of the primary papers claiming that the mineral concentrations in raw fruit and vegetables available in the UK have declined since the 1930s [1-3] and will determine whether sufficient data is available in the literature to test this hypothesis. If sufficient data can be sourced, the hypothesis will be tested statistically.If the mineral concentrations in horticultural produce available in the UK is declining, then there are immediate opportunities to improve crop genotypes and cultural practices to ameliorate the problem. We will, therefore, review and recommend future research options to determine the impact of contrasting crop genotypes and cultural practices on the mineral concentrations in horticultural crops. This is also a research area of global importance as efforts to sate the `hidden hunger` caused by insufficent mineral nutrients in the human diet are becoming urgent. In the second project, we propose to investigate the use of various agronomic manipulations on the Gamma-linolenic acid (GLA, 18:3) content of blackcurrant seeds. Gamma-linolenic acid is a naturally occurring fatty acid found in the seed oils of borage, evening primrose and blackcurrant. GLA is nutritionally very important to humans and has recently been shown to have a number of therapeutic applications including anti-cancer activity and alleviating atopic eczema. The use of high quality GLA in the pharmaceutical industry is dependent on a continuous and reliable source. Large-scale production from borage and evening primrose is expensive and utilising the waste products from blackcurrant juice manufacturing would be economically more viable. Currently, blackcurrant seed is under exploited because the quality of the seed oil is not consistent year to year and, crucially, GLA needs to be over 15% of the total normalised fatty acids in the seed to ensure its adoption by the most profitable sector of the market [6]. Nevertheless, the quality of GLA in the seed oil of blackcurrant has reached 14.6% in certain years for commercial varieties. A few surveys have been conducted to quantify the amount of GLA in the seed oil of various Ribes cultivars [7,8]. Although over 15% GLA in the seed was observed for some of the blackcurrant varieties investigated, they are not of commercial interest to the UK industry. However, there is evidence that environmental manipulation can enhance GLA accumulation [9], but, to our knowledge, controlled agronomic trials to enhance GLA content have not been performed. According to a recent study in Canada, varying nitrogen fertilisation may have an effect on GLA content, but states that further controlled investigations are required [10]. We will use containerised blackcurrant plants to allow accurate manipulation of nitrogen fertilisation to the soil. Partial root drying (PRD) will be applied to plants to assess the effects of water stress, and manipulation of crop load will also be carried out. The effect of these cultural manipulations on the GLA content of seeds will be determined and their commercial potential will be assessed.
Objective
Project 1 has three objectives:
01 To source and annotate summary data on the mineral content of fruit and vegetables available in the UK and USA in the 1930s and the present day.
02 To ascertain whether sufficient data is available, and if so, to test the hypothesis that the concentrations of minerals in fruit and vegetables in the UK has declined since the 1930s.
03 To recommend future research options to investigate how contrasting crop genotypes and cultural practices impact on the mineral content of fruit and vegetables in the UK.
Project 2 has three objectives:
04 To subject blackcurrant plants to different agronomic treatments (nitrogen deficiency, crop loading and RDI).
05 To determine the amount of GLA present in the seeds of ripe blackcurrant fruit.
06 To establish an in vitro blackcurrant tissue culture line.

Project 1 and 2 are independent. In the first project: Obtaining and collating data on the composition of crops, determining whether there is sufficient data to test the null hypothesis that the mineral content of horticultural crops has not declined and testing this hypothesis are sequential objectives, but can be performed independently for the UK and USA data. A comparison of the UK and USA data requires both data sets, and critiques of the papers by Mayer (1997) [1] and Thomas (2000ab) [2,3] will be informed by the analysis of both data sets. The design of experiments to test hypotheses arising from the interpretation of the available data and technology transfer can begin following the collation and analysis of the UK data.

In the second project, objectives 04 and 05 are inter-related.
Project Documents
• Final Report : Mineral and nutritional content of produce   (857k)
Time-Scale and Cost
From: 2003

To: 2004

Cost: £88,030
Contractor / Funded Organisations
Horticulture Research International
Keywords
Farming              
Fruit              
Horticulture              
Nutrition              
Vegetables              
Fields of Study
Horticulture
Horticulture