Research Documents
The Proof is Easy to See!
Breakthrough research from the University of Toronto shows that Vitamix processing may significantly enhance nutrient intake from whole foods
The results of a 2008 study at the University of Toronto clearly indicate that the Vitamix 5200 has the ability to disrupt plant cell wall structure and significantly reduce food particle size which may enhance the bioavailability of essential nutrients in fruits and vegetables.
Effect of Vita-Mix blender vs a control blender and chewing on the particle size of different fruits and vegetables.
Aims: To determine whether different processing methods influence particle size, plant cell wall structure and nutrient bioaccessibility.
Hypotheses: Processing by means of a newly developed high speed blender will increase disruption of plant cell wall structure and decrease particle size thereby enhancing nutrient bioaccessibility.
Background: In plant food tissues, the physico-chemical structure and properties of cell walls in the gastrointestinal lumen are critical factors involved in influencing bioaccessibility of nutrients (1,2).
Bioaccessiblity is defined as the proportion of nutrients released from a food matrix, and therefore, potentially available for absorption in the gastrointestinal tract (3). Thus, the intact cell walls of starch-rich leguminous (4) and lipid-rich almond seeds (3) act as a barrier to the action of gut enzymes, hindering the rate and extent of starch and lipid digestion, respectively. As such, consumption of nuts results in increased fecal excretion of lipids due to incomplete disruption of plant cell wall structure, and reduces bioaccessibility of almond lipids (3).
The physiologic effects of the plant cell wall and how intracellular nutrients are released will depend on the physical state of the plant tissue in the gut lumen. A critical factor will be whether the cell walls are disrupted during processing and chewing and during transit along the gastrointestinal tract (1,2). The processing of plant foods (e.g. milling, homogenization, cooking, blending) may influence the bioaccessibility of starch, lipid and other nutrients, mainly as a result of changes in cell wall structure and properties.
The aim of the present study was therefore, to determine if a novel high speed blending methodology would increase plant cell wall disruption, decrease plant tissue particle size and enhance nutrient bioaccessibiltiy compared to a standard processing method and chewing.
Methods:
Test Products: For this study, three plant foods, carrot, tomato and strawberry were selected. These foods were selected as they represent a spectrum of the degree of plant cells wall hardness and therefore, provide a good indication of the effectiveness of this novel processing method, across a broad range of foods.
Chewing and Blending Studies: To assess the effects of chewing on the physical disruption of cell wall structure and plant tissue particle size, a method based on the technique developed by Granfeldt et al (5) was used. The volunteer was asked not to eat for 2 hours before the experiment and was instructed to rinse their mouth with drinking water (bottled, still) and then chew a sample of the plant food of interest, carrot, tomato, strawberry until it was ready to be swallowed. The volunteer was then asked to expectorate the contents of their mouth into a petri dish, samples of which were then immediately chemically fixed and later stained and examined by microscopy, as described in the section ’Microstructural Analysis’. The volunteer was then asked to repeat this procedure for all of the test products.
To assess the effects of blending on the physical disruption of cell wall structure and plant tissue particle size, two blenders were studied, a standard household blender and the newly developed high speed novel blender. For each test, 100 mL of the test food will be placed in the blender along with 100 mL distilled water. The samples will then be blended at the highest speed setting for 60 seconds. The blended sample was poured into a funnel and filtered through filter paper (Watman) to remove excess water. After filtering a sample of the plant tissue will be taken for immediate chemical fixation and later stained and examined by microscopy, as described in the section Microstructural Analysis.
Microstructural Analysis: The chewed and blended plant tissue samples were examined by light and scanning electron microscopy to assess the morphology of the plant cell wall structure and particle size. Samples were placed in capped test tubes containing a fixative, 2.5% (wt:vol) paraformaldehyde and 0.5% (by vol) Glutaraldehyde ) in 0.1M phospate buffer PH 7.2,and refrigerated until further processing.
Subsequently, all samples were washed twice, each time for 30 min, in 0.1 M phosphate buffer and then post-fixed in 1% (wt:vol) osmium textroxide for 2 hours, also in 0.1M phospate buffer (PH 7.2). Samples were dehydrated in graded ethanol serial dilutions 50%, 70%, and 90%, (by volume ethanol and distilled water) for 30 min for each solution and finally, in 100% ethanol for 30 min (3 times).
For light microscopy, the plant tissue samples were infiltrated with Spurr resin and embedded in molds and polymerized at 60(C. Sections (1(m ) were cut on a Reichert Ultracut ultramicrotome ((Leica Microsystems Ltd), mounted on glass slides and stained in 1% (wt:vol) Toluidine Blue.
For examination by scanning electron microscopy, samples were critical point dried in a Polaron E3000 CP Drier (Quorum Technologies), mounted on stubs, and sputter coated with gold in a Polaron E5100 sputter coating unit and viewed with a Hiitachi S3400 Variable Pressure scanning electron microscope.
Plant tissue particle size was determined from analysis of the generated scanning electron micrographs using adapted computer software (NIH Image J) specifically designed for particle size analysis.
Statistics: Paired Student’s t-tests (2 tailed) were performed on the quantitative particle size data. Statistical differences between the chewing, control blender and test blender were accepted at P<0.05.
Significance of study: The study provides useful information on the ability of a novel processing method to increase cell wall disruption and decrease plant cell tissue particle size. These data may indicate that a novel blending method can enhance nutrient bioaccessiblity.
This study also helps to establish possible mechanisms by which plant food processing may influence cell wall structure and plant tissue particle size and may be of value in increasing nutrient bioavailability.
References
MacDougall AJ, Selvedran RR. Chemistry, architecture, and composition of dietary fiber from plant cell walls. In: Cho SS, Dreher ML, eds. Handbook of dietary fiber. New York: Marcel Dekker Inc, 2001: 281-319.
Waldron KW, Smith AC, Parr AJ, et al. New approaches to understanding and controlling cell separation in relation to fruit and vegetable texture. Trends Food Sci Technol 1997;8:213-21.
Ellis PR, Kendall CW, Ren Y, et al. Role of cell walls in the bioaccessibility of lipids in almonds seeds. Am J Clin Nutr 2004;80:604-13.
Noah L, Guillon F, Bouchet B, et al. Digestion of carbohydrate from white beans (Phaseolus vulgaris L.) in healthy humans. J Nutr 1998;128:977-85.
Granfeldt Y, Bjorck, Drews A, Tovar J. An in vitro procedure based on chewing to predict metabolic response to starch in cereal and legume products. Eur J Clin Nutr 1992;46:649-60.