Location: Horticultural Crops Research2010 Annual Report
1a. Objectives (from AD-416)
1) Evaluate liquid dehydration methods, freeze drying and Radiant Zone Drying, to produce a pure powder with no maltodextrin or 20% maltodextrin (w/w of puree solids) from purees of whole blueberry and strawberry. 2) Measure phenolic composition, total phenolics, total anthocyanins, and total antioxidant activity of dried powder as compared to the fresh berry. Additionally, for strawberry determine ascorbic acid and volatile losses on drying. 3) Evaluate dried powder for suitability for use as a nutritional supplement ingredient by measuring microbiological content moisture content, water activity, bulk density, hygroscopicity, degree of caking, and flowability. 4) Evaluate shelf-life of powders at 1 year by measuring parameters listed in 2 and 3 above.
1b. Approach (from AD-416)
Whole blueberries and strawberries will be pureed and if not immediately dried will be frozen at -4ºC until drying. The berry puree will be dried without maltodextrin (carrier-free) or blended with 20% maltodextrin based on the solids content of the berry. The carrier-free and maltodextrin blend will be dehydrated at optimum drying conditions based on previous literature and operator experience. Using drying conditions that achieve a dry powder, the trials will be conducted in triplicate and the resulting data subjected to analysis of variance (ANOVA). Drying parameters such as time, temperature and yield will be recorded to determine throughput and estimate cost of production. The dried puree powders will be milled and sifted to obtain a homogenous 100% through a 40 mesh screen powder. Powders will be stored in moisture proof HDPE (high density polyethylene) metalized packaging in a dehumidified room at room temperature to replicate typical storage treatments in the Industry. Blueberry and strawberry puree samples and powder samples will be evaluated and compared for total antioxidant activity. Phenolic profiles will be measured using High Performance Liquid Chromatography (HPLC) to determine loss on drying and changes in phenolic profile. Two additional analyses will be performed on strawberry, volatiles using gas chromatography and ascorbic acid content using a spectrophotometer. Analysis will be run in triplicate on homogenous puree and dried samples. Dried powder samples will be stored for one year and all analysis will be repeated to evaluate storage /shelf life on these parameters. Documents Grant with Washington State University.
3. Progress Report
In year two of this three year proposal, we were to dry raspberry and blackberry on a freeze dryer located at the WSU pilot plant, Pullman WA, and the Radiant Zone Dryer at Columbia PhytoTechnology, LLC, Dallesport, WA. We instead focused on cranberry and raspberry because Milne Fruit Products donated the cranberry puree and juice concentrate. Additionally, because we saw relatively low losses on both the Radiant Zone Dryer and Freeze Dryer, for cranberry we focused on the benefit of carrier additions and the differences between puree and juice concentrate formulations. We analyzed the cranberry formulations for physical characteristics, color, total phenolics, anthocyanins proanthocyanidins and anthocyanin profile. We are nearing completion on the manuscript describing the cranberry research. We have conducted the raspberry drying on the Radiant Zone Dryer, but have not freeze dried it or completed the analysis. We have also completed all work on the strawberry portion of the work and have completed a manuscript for submission into the Journal of Agricultural and Food Chemistry. Methods of ADODR monitoring included meetings, e-mail, and phone calls.