AGRE-0016 Adding Value to European Maize use in the Starch Industry in Relation to Growing Areas and Cultivation Techniques used

Summary Information



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ECLAIR Cluster III - Carbohydrates : Protein/Amino Acid : Starch

SUMMARY

The maize (corn) wet-milling industry consumes between five and six million tons of maize every year, most of which comes from within the European Union (EU). However, the quality is variable. This project compared the extractability of various maize kernel components and the industrial properties of the starch extracted from experimental samples collected from various maize producing regions of the EU. The varieties of maize used, type of kernel, production areas and growing techniques were all varied with the objective of focusing maize growers on the choice of hybrids and growing techniques most suited for supplying the European wet-milling industry with maize of optimal quality. The experimental starch samples were then characterised in public and private (industrial) research laboratories. A considerable amount of data was collected - the main variable affecting quality appeared to be the (uncontrollable) climatic conditions in any season.

INTRODUCTION

The maize (corn) wet-milling industry consumes between five and six million tons of European maize every year, practically all of which comes from within the European Union. However, the quality (suitability for milling) is variable. This research project compared the extractability of various maize kernel components and the industrial properties of the starch extracted from experimental samples collected from several maize producing regions in the European Union. The varieties of maize used, type of kernel, production areas and growing techniques were all varied with the objective of focusing maize growers on the choice of hybrids and growing techniques most suited for supplying the European wet-milling industry with maize of optimal quality. This was done by looking at starch obtained by means of a wet process in a pilot plant capable of processing small experimental batches (around 15 kg). The experimental starch samples were then characterised in public and private (industrial) research laboratories.

ACTIVITES

Over 800 samples of maize kernels were collected in the field from plants grown under controlled conditions during 1990, 1991 and 1992 in regions with different and even extreme climates for maize growing (Belgium and Northern France, Southern France, Spain and Greece). The cobs were hand-picked and air-dried or slightly heated before being shelled, to avoid any effect of harvesting and drying conditions likely to mask the eventual influence of growing conditions on the wet-milling properties. Following assessment of the agronomic performance, 128 samples of grain were chosen for further examination in the pilot facility:
30 samples from variety trials; 62 samples from nitrogen fertilisation trials; 26 samples from irrigation trials; and 10 samples from crop density trials. Each sample was obtained by mixing material from the 4 basic repetitions in the field to provide the pilot facility with at least 15 kg of grain per treatment. The wet-milling extraction process, agreed by the industrial partners, was unchanged throughout the programme, irrespective of the type, size or origin of the kernels. The performance of the pilot facility was below that of an industrial plant. The samples of starch and gluten were analysed using protocols specific to each laboratory. Over 10,000 data-sets were recorded in a data-bank. Priority criteria were adopted by the partners. Correlation, main component and variance analyses were performed.

RESULTS

Despite very different production conditions, resulting in extremely variable agronomic results (in yield, kernel weight etc.), especially in the irrigation and nitrogen fertilisation trials, the starch extractability functional properties were, overall, little affected by the growing conditions and varietal types. In particular, it was found that the usual methods and levels of nitrogen fertilisation for maize have no influence on starch quality, whilst even a very severe restriction of water throughout the maize cycle failed to produce any noticeable reduction in the starch properties and recovery rate. Water deficit after silking (a specific stage of flower development), however, resulted in a significant reduction in the first extract starch recovery, without altering the starch properties. The geographical area of production had no effect on the extraction results, whereas the agronomic results differed between Northern Europe (growing early flint-dent varieties) and Southern Europe (growing late dent varieties). The gelatinisation temperature of the starch samples from Belgium (the coldest area) was lower than the gelatinisation temperatures observed in the other areas. An unexplained difference, related to the year of production, was found in respect of extraction. Inbred lines of particular value as a source of flouriness were detected. These were converted into a large number of genitors for the ultra-rapid production of starch inbred lines by the use of in situ haplodiploidisation with a minimal induction of 2%. In the semi-early varieties, pure dent hybrids more floury than the flint-dent varieties grown were detected.

EXPLOITATION

The hypothesis was put forward that the starch-protein-lipids bonds depend not only on the filling of the kernels but also on the drying speed. At present further work is required to understand the bonding mechanisms between the starch granules, proteins and lipids during the ripening of the maize kernel.

PARTICIPANTS

ITCF, Boigneville (France), Cerestar Italia Srl, Milan (Italy), INRA, GMP Centre, Thiverval Grignon (France), Instituto Técnico Agricola y Granadera Aragon, Huesca (Spain), INRA, Plant Improvement Station, Clermont Ferrand (France), Catholic University of Louvain (Belgium), INRA, Nantes (France), Roquette Frčres S.A., Lestrem (France), Amylum NV, Aalst (Belgium), INRA-CRAM, Montpellier (France), University of Strathclyde, Food Science Division (UK), CNRS, Meudon (France) and the Cereal Institute, Thermi Thessaloníki (Greece).