Technical Sessions

Highlights

Symposia

Division Updates

Technical Sessions
The following reports were furnished by the chairs of a majority of the Technical Sessions at the 1999 annual meeting. They provide an overview of the scientific presentations offered in Seattle, and include valuable summary information for those not able to attend the meeting, or who were unable to get to all of the sessions.

Milling
Baking I
Analytical Methodology I
Extrusion
Rice
Starch I
Biotechnology
Baking II
Nutrition
Protein
Starch II

Attendance: Attendance was somewhat low.

Changes in the program (e.g., presenters, withdrawals) Colin Webb presented the second of the two UMIST papers in place of Grant Campbell, who was scheduled to present another paper in a different session at the same time.

General focus of session: The session focused on milling performance and, to some extent, its prediction. With the exception of the first paper which concerned corn milling, all papers were focused on wheat milling. The link between milling performance and kernel characteristics was made by a number of presenters.

Session highlights, special audience interest, or topics generation discussion: Although there were questions for every presenter, no extended discussions got underway. The two papers from UMIST, in the UK, showed that the ability to simulate and predict milling performance mathematically is becoming established and this will ultimately be linked back to physico-chemical properties of individual kernels.

Summary/conclusion or common themes from the session: Although not a core interest for cereal chemists, the convergence of cereal chemistry and milling is becoming ever more apparent.

Additional comments: The session was a truly international one, with none of the six speakers originating from the U.S., though two were representing U.S. universities.

Attendance: 100-125

Changes in program (e.g., presenters, withdrawals) Paper #305 was not presented.

General focus of session: The general focus of the Baking I session was on innovations to
improve bread baking performance. M.G. Lindhaur presented data showing that dried vital wheat gluten can improve the mixing and handling properties of bread doughs and the break and shred of breads produced using relatively weak flours. M. Seguchi described the improving action of gaseous acetic acid treatment on bread making. Treatment to pH 4.0 - 4.9 increased yeast physiology and produced good quality bread characteristics using flours of varying protein content. Lower protein flours required less treatment. Lower acetic acid levels produced breads with better sensory properties. C. Courtin described a study that utilized varying specificities of endoxylanase activities to degrade arabinoxylan and observed their effects on the bread making process. Different solubilities of enzymes caused effects to be observed during mixing or after fermentation. E.E. Holton showed the improving effects of low lactose, low mineral whey protein isolate on the mixing and pasting properties of flours. Up to 8% whey protein isolate was added in this study. J. Rasanen illustrated studies utilizing carboxymethylcellulose to improve the stability of prefermented and frozen lean wheat doughs. CMC formed a continuous matrix with gluten. After 14 days frozen storage, breadbaking results with CMC were equivalent to fresh baking. J.M. Higgings discussed the application of carbohydrate hydrolases to breadmaking. It was observed that adding various enzymes having xylanase activity produced residual activity in baked bread. Residual B - exlanase activity was associated with softer breadcrumb up to 72 hours storage.

Attendance: 40-50, for each of the eight presentations

Changes in program: Presentation #295 was given by D.L. Wetzel, Kansas State University, rather than J.A. Sweat.

General focus of session: Major focus of the session was NIR analysis of cereal grains for quality factors. There was two presentations dealing with other subjects. One presentation was on continuous NIR monitoring of moisture in and development of dough. Another described the use of supercritical fluid extraction in conjunction with HPLC for screening of desirable lipids in wheat. The major point made by the presentations was that calibrations of NIR instruments are essential and that they be made carefully. The calibrations must be made on each grain and for each component of interest (moisture, weight, protein, hardness index etc.). Evaluation of dough by the standard Labtron Mixer method and the continuous NIR method showed good correlation between methods. The NIR method may provide more detailed information on water's effects on dough. The use of supercritical fluid extraction in conjunction with HPLC provides for separation of polar/nonpolar lipids and greatly reduces analysis time. These are desirable factors considered in choosing a method of analysis.

Summary/conclusions or common themes from the session: That NIR is a useful tool in determining the quality of grain and in understanding the process of dough development. The use of NIR in quality evaluation of grains will continue to increase. Both the use of NIR in evaluating dough development and the use of supercritical fluid extraction/HPLC for lipids in wheat are tools likely to become routine.

Attendance: 45-50 depending on topic

Changes in the program (e.g., presenters, withdrawals) Paper #316 by C. Mair and K. Matson was withdrawn. Paper #318 by P.K. Bath and N. Singh was not presented.

General focus of session: The session focused on extrusion as a process. B. Strahm talked about controlling glass and melt transitions of complex recipes using the closed chamber capillary rheometer. J.F. Faller presented the effect/influence of corn hybrids from different growing areas on extrusion product characteristics of an extruded snack type product. S. Pierce spoke about the use of emulsifier and processing aids on the quality of a corn curl type snack product. G.H. Ryu presented information on the effects of extrusion conditions on the characteristics of extruded powders for instant cereal drinks.

Session highlights, special interest, or topics generating discussion: All of the papers generated questions from the audience, most of the questions dealt with controlling glass and melt transitions and the use of processing aids and emulsifiers to influence the quality of a corn curl type snack product.

Summary/conclusion or common themes from the session: The common theme of most of the papers was the effects of extrusion processing parameters and processing aids on the quality characteristics of the extruded products.

Additional comments: The two papers not presented were back to back and much of the time was used for additional questions for the first two presenters and individual discussions.

Attendance: 15-35

General Focus of session: The session focused on physical property characterization of rice, effects of blast damage on rice quality and application of glass transition temperature in rice drying. A. G. Cnossen described a hypothesis relating glass transition temperature in fissure formation in rice kernels in drying and how it affects the head rice yield. R.C. Bautista discussed rice kernel moisture content and size distributions at harvest and during drying as a source of fundamental information to optimize rice-processing operations, particularly drying. He further explains fissure formation in the field while the crop is maturing and showed optimum harvest moisture content to save more kernels from fissuring. B.L. Candole centered his discussions on the effect of rice panicle blast on the physical and quality aspects of rice.

Session highlights, special audience interest, or topics generating discussion: Particular issue of interest in the discussion was on the glass transition of rice kernel. Efforts should provide more information on how glass transition curves can be generated effectively. Discussion on rice kernel property characterization also drew attention as to the variability in moisture content and size distributions because they affect processing operations. Chemical properties of damaged kernels were altered by panicle blast.

Summary / Conclusions or common themes from the session: Understanding of fundamental properties of rice to enhance processing qualities. Rice quality can be maintained or improved by knowing its physicochemical properties and application of polymer science in processing, particularly drying. Milled rice quality is affected by panicle blast.

Attendance: 75-150 Depending on topic

Changes in the program: V.M.F. Lai presented paper #355 in place of S.Y. Lin.

General Focus of Session: There were three general topics discussed: (1) Understanding starch retrogradation; (2) Interactions between starch-protein-lipid; (3) Characterization of various starches and starch fractions.

Session highlights: Retrogradation kinetics were actively discussed. However, the papers on
starch-protein-lipid and starch-lipid interactions generated more discussion. The presence of linoleic acid as a free fatty acid was believed to increase viscosity and decrease syneresis of a starch paste. Palmitic acid, however, had the opposite effect. The length of the amylose and the length of the fatty acid chain apparently influenced crystal formation. On another note, characterization of the two new starch granule bound proteins generated much discussion as to the mechanism by which B-type granules are formed.

Summary/conclusion or common themes from the session: There was no single theme between papers but the audience appeared interested in all aspects of starch.

Attendance: started at 25, soon reached and remained at 75-80.

Changes in the Program: There were two substitute speakers. Colin Wrigley
gave the presentation "WheatRite: An immunochromatography field test for
preharvest sprouting" in place of J.H. Skerritt. Charles Hecht gave the presentation "Genetically modified crops: Are you DNAware?" in place of B. Popping.

General Focus of session: One group of talks provided overviews of methods and their
applications. C. Wrigley explained a new test kit for preharvest sprouting that can be used in fields and elevators. J. Zhu reported changes in HMW-glutenin subunit amounts and their polymer distribution in wheat grown under two fertilization regimes. S. Delwiche showed that completely waxy wheat could be readily distinguished from partially waxy by NIR. C. Hecht explained methods used to detect transgenes in commodities and foods. J.K. Vasil and A. Blechl both reported that adding extra copies of native HMW-glutenin genes to wheat by genetic transformation increased dough mixing times. S. Netrphan reported isolation of genes encoding wheat isoamylases.

Session highlights, special audience interest, or topics generating discussion: Dr. Wrigley provided samples of the Wheat Rite test kits for preharvest sprouting and these were quickly snapped up by the audience to examine and try at home. S. Nterphan's talk generated a lively exchange about nomenclature for enzymes with starch debranching activities. Both Dr. Vasil and Dr. Blechl noted the appearance of novel protein species in
seed extracts from plants transformed with HMW-glutenin genes.

Summary/conclusions or common themes: A variety of protein and DNA methodologies are being applied to measuring and understanding various aspects of wheat end-use quality. This first technical session sponsored by the Biotechnology Division provided a forum for discussing these techniques in detail and complemented two symposia at this year's annual
meeting in which the impacts of biotechnology on the food business were the featured topics.

Attendance: 75-100

Changes in the program (e.g. presenters, withdrawals): Paper 347 was presented by S. Gunasekaran and paper 351 was presented by D.L. Brabec. Paper 352 by K. Kaur and N. Singh was withdrawn.

General focus of session: In contrast with the Baking I session, the focus here was not primarily on ingredient effects, but on the quantification of dough and bread properties. Four papers examined dough properties as determined by mixing characteristics or by biaxial extensional rheology using dough inflation. The emphasis of the former was on informative, quantitative analysis of power consumption during mixing as a basis, inter alia, for on-line control of dough mixing. Dough inflation was presented as a tool yielding fundamental rheological parameters for use in predicting baking performance based on the strain hardening properties of doughs, and in assessing the effects of enzymes and emulsifiers on dough rheology. Two papers then focused on baked loaf quality, firstly in terms of retarding staling by maltogenic alpha-amylase, and secondly looking at how bread crumb structure affects the mechanical properties. Finally, the effectiveness of different xylanases on dough and bread quality was explored in relation to inhibition kinetics.

Session highlights, special audience interest, or topics generating discussion: It was interesting to have a paper describing a rheological tool to measure properties of bubbles (formation and stability) and have this followed by the successful practical application of the tool by an industry for measuring efficiency of various dough conditioners.

Summary/conclusions or common themes from the session: Bread quality starts with dough mixing, but the structure established here is then converted via proofing and baking. Baked loaf quality may be assessed quantitatively by mechanical or sensory tests, but the point of action of dough rheology and various ingredients is not certain – do they act primarily during proofing or during the early stages of baking?

Additional comments: Evidently the tools now exist for quantitative characterization of dough and bread. It behooves us to use these tools to understand breadmaking mechanistically, not just empirically, and to concern ourselves with processing as well as ingredient effects.

Attendance: 40-50

Changes in the program (e.g., presenters, withdrawals) Paper 388 given by Dr. Camacho-Solás (MD) advisor to the MOTT Mexico Government not P. Ranum. Paper 382 given by Gur Ranhotra not Stacey Leinen

General focus of session: Primarily enrichment/ fortification, Ca and Fe and Folate; Resistant starch survey in products; Value of rye (rye-bread) for health benefits - glucose/insulin response, blood lipids, colon function.

Session highlights, special audience interest, or topics generating discussion: 3-5 questions per speaker, very lively.

Summary/conclusion or common themes from the session: Nutritional value of cereals continues to get a lot of attention, including as a vehicle for fortification.

Attendance: 40-60

Changes in the program (e.g., presenters, withdrawals) Frank Tenbarge presented #396 for M. Embuscado

General focus of session: Three talks centered on the role of glutenin sub-units and glutenin polymers in flour quality. H. Nakamura discussed the high molecular weight glutenin sub-units of Japanese wheat varieties. He discovered that many varieties that are used for noodle making have an unusual 145 kD sub-unit. C. Lukie discussed the Canadian Western Extra Strong wheats and the correlations between glutenin components and dough properties. W.S. Veraverbeke described in-vitro polymerization of glutenin subunits. The rest of the talks were on other grain proteins. F.M. Anjun talked about friabilins, M. Mikola described the role of oat proteinases during germination, and F. Tenbarge discussed methods to use proteinases to remove zeins from cornstarch. The two students, W.S. Veraverbeke and C. Lukie, both gave excellent talks and will each receive the $50 "best presentation" awards given by the Protein Division.

Attendance: 50-100, depending on topic

Changes in program (e.g., presenters, withdrawals) 355 Dr. V.M. F. Lai presented for Dr. S.Y. Lin who was unable to attend.

General focus of session: The session focused on starch retorgradation, crystallization, and interactions. I.A. Farhat demonstrated the applicability of quantitative simulations using several polymer science models to examine starch retrogradation processes and experimental results. V.M.F. Lai presented results on the two-stage retrogradation kinetics of rice amylopectins. A. Buleon used temperature-dependent X-ray diffraction to monitor the crystallization of amylose-lipid complexes during maize melting. Dr. Lai (for Dr. Lin) discussed the interactions between rice and wheat starches during gelatinization and G. Zhang examined starch protein lipid interaction in a model food system. L.T. Nguyen discussed the physicochemical properties of prime and tailings starches from barley and B.-K. Baik discussed the properties of pasting and gels for wheat starches. M. Peng presented some biochemical studies of the A- and B-type granules in wheat endosperm.

Session highlights, special audience interest, or topics generating discussion: Demonstration of 3-way interaction between starch-protein-lipids in a model food system. Biochemical characterization of 3 polypeptides related to differentiation of A & B type granules in wheat starch. Quantitative characterization of retrogradation kinetics and processes with a variety of experimental techniques and descriptions that can be used to simulate the experimental data.

Summary/conclusion or common themes from the session: A diverse range of experimental techniques, theoretical models and approaches (biochemical, polymer science, etc.) are being used to study starch retrogradation, gelatinization, crystallization processes as well as physicochemical properties. While much progress has been made in understanding particular aspects in some systems, there remains more to be done.

Copyright © 1999 American Association of Cereal Chemists, Inc. all rights reserved