Location: Healthy Processed Foods Research
2015 Annual Report
Objectives
The long-term goal of this project is to develop novel methods, and define measure and mitigate attributes that adversely impact the quality of foods. Specifically, during the next five years we will focus on the following objectives:
Objective 1: Enable novel commercial methods for prevention or removal of defects and contaminants in foods.
• Subobjective 1A: Develop techniques for detection and removal of potatoes affected by Zebra Chip disorder from the processing line.
• Subobjective 1B: Develop X-ray based alternatives to radioisotopes for irradiation.
Objective 2: Integrate physical, chemical, sensory, and biological changes from raw and commercially processed food products, including, olives and grapes.
• Subobjective 2A: Pinpoint and identify impact aroma compounds of raw materials and commercially processed products from specialty crops including grapes and olives using gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). Identify precursors (and eventually pathways) of such impact aroma compounds and study flavor variation in different varieties.
• Subobjective 2B: Isolate and characterize phytonutrients in raw materials and food products from grapes, olives, and other specialty crops. Determine the effects of processing on the levels of these constituents and also monitor changes in biological activity (i.e., antioxidant activity).
Objective 3: Integrate measurable allergenic properties with methods to mitigate food allergens in nuts and dairy.
• Subobjective 3A: Identify, characterize, and develop methods for the detection of food allergens in tree nut and other foods.
• Subobjective 3B: Investigate and differentiate allergen cross-reactivity and multi-sensitization and study the effects of processing methodologies on allergenicity.
Approach
1A: Acquire x-ray images and NIR spectra from whole potatoes (reflection) and through slices (transmission). Analyze slices for moisture and sugar, followed by frying and color evaluation. Develop calibration equations for prediction of Zebra Chip (ZC), moisture content, sucrose, and glucose and investigate correlations between ZC and moisture and/or sugar. Isolate appropriate subsets of NIR absorbance values as input features for standard statistical classification techniques. Test appropriate optics that can measure absorption at the determined wavelengths for the ability to evaluate ZC. Observe x-ray images for differences between potato classes and develop detection algorithms. 1B: Design, build, and test x-ray based irradiation units was alternatives to traditional gamma based units using two technologies: traditional x-ray tubes and a higher power prototype x-ray emitter system.
2A: Extract aroma compounds from grapes and olives using GC. Identify precursors and study flavor variation in plant varieties. Have judges evaluate ability to detect odor from each compound’s effluent from a GC column, with compounds detected in the most dilute sample considered to be impact aroma compounds. Identify acquired capillary GC-MS spectra using established libraries to identify food constituents. Quantify food constituents by GC-MS by comparing the areas of characteristic mass fragment ions of the compounds with that of 2-undecanone (m/z 170). Calculate odor activity values by dividing the determined concentrations by their odor thresholds. For confirmation, compare synthetic blends of identified odorants with those of the original raw and processed products using sensory panels.
2B: Extract homogenates from processed and unprocessed food components and analyze using an HPLC-diode array detector. Identify constituents by comparison of retention times and UV/Vis spectra of unknown peaks with those of authentic standards and verify by HPLC-MS, NMR or IR if necessary. Determine weight and total phenolic content for each homogenate. Evaluate antioxidant activity by the DPPH and ABTS procedures. Determine effects of processing by comparison.
3A: Isolate 2S albumins from nuts and express recombinantly to assess their allergenicity using sera from allergic patients. Isolate and express profilin protein for comparative studies. Develop protocols to purify 2S albumin allergens in other nuts including almond, pine nut, coconut, macadamia nut, and optionally chestnut. Determine the peptide sequences by N-terminal peptide sequencing and mass spectrometry. Develop antibody based methods for detecting food allergen and allergic food.
3B: Isolate and clone hazelnut allergens following established protocols. Assay association with serum IgE from patients known to react to peanut and/or hazelnut. Frequency of IgE recognition of allergens will reflect cross-reactivity and multi-sensitization. Process samples by extrusion to investigate processing effects on allergenicity.
Progress Report
This is a new project replacing three terminating projects: 2030-44000-010-00D, "Quality Based Inspection and Sorting of Specialty Crops Using Imaging and Physical Methods"; 2030-44000-057-00D, "Reduction of Allergenicity through Food Processing," and 2030-41000-053-00D, "Optimization of the Nutritional, Functional and Sensory Properties of Raw and Processed Legumes, Grains and Specialty Crops." Progress is reported in the annual reports for each terminating project. Since the new project has only been active since July 1, 2015, there is limited progress to report. However, preliminary work has been completed establishing near-infrared (NIR) spectroscopy protocols for fruit which will be applicable to potato analysis (objective 1A) once samples become available in late September or October. The x-ray emitter system is operational at low power (objective 1B) and is ready to be fully implemented as soon as power is hooked up in the concrete facility. Work has begun to establish appropriate sample preparation methods for isolation of black-ripe olive flavor constituents (objective 2A) as well as the phenolic constituents of grapes (objective 1B). Work has also begun to develop protocols and secure samples required to purify Profilin from economically important tree nuts (objective 3 A&B).
Accomplishments
