Location: Healthy Processed Foods Research
2019 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
In support of Sub-objective 1A, a number of optical configurations measuring reflected light at particular wavelengths, as determined in previous experiments for their ability to discriminate the classes of interest (i.e. Zebra Chip disease), have been assembled and tested. Discrimination accuracy is lower than that achieved using the reduced near infrared (NIR) spectra in combinations with chemometrics (published previously), presumably due to optical limitations in isolating specific wavelengths and the rapid signal acquisition time as compared to the spectrophotometer signal acquisition time. Experiments with different optical configurations are ongoing.
In support of Sub-objective 1B, dose mapping experiments have continued. A novel irradiation configuration in which samples are confined to the surface of a wheel which rotates below an x-ray source has been developed. This configuration allows a highly uniform dose distribution among samples as well as very precise dose determination.
Under Sub-objective 2A, impact aroma compounds in different olive varieties were identified and quantified using gas chromatography-flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Odor unit values were calculated to determine the contribution of individual odor constituents to the overall flavor. These results will help growers and processors to understand differences in flavor characteristics among the different olive varieties.
In support of Sub-objective 2B, research focused on grape pomace which consists of pressed skins, seeds and stems, which account for about 20 percent of the weight of the fruit. Approximately 10 million tons of pomace are produced annually from wineries, creating environmental challenges and significant waste. Phenolic composition of grape pomace skins from four red wine cultivars (Carignan, Merlot, Cabernet Sauvignon, and Syrah) have been studied. Carignan skin appears to hold the most promise as a source of phenolics among these cultivars due to its high concentrations of caftaric acid, rutin, quercetin 3-glucoside, kaempferol 3-glucoside, and resveratrol. Given the health benefits of phenolic compounds (including anti-inflammatory, anti-ischemic, anti-obesity, and anti-platelet aggregating effects) the potential use of this waste stream for extraction of phenolic compounds is indicated.
In support of Sub-objectives 3A and 3B, the gene of an antimicrobial protein of almond has been isolated. The recombinant protein has been expressed and purified. It has been identified as an almond allergen by testing its immunological reactivity with sera from almond allergic patients and it has been officially designated as Pru du 8 by the World Health Organization and International Union of Immunological Societies (WHO/IUIS) Allergen Nomenclature Sub-committee. The recombinant almond allergen is being used to generate reagents for studying its allergenic property and for identifying additional food allergens in other foods.
In support of Sub-objective 3B, rat basophil cell line RBL-2H3 has been humanized and is being tested. The humanized cell line will allow us to effectively assess food allergen cross-reactivity and food processing effect on the allergenic property of food allergens.
Accomplishments
1. New x-ray based irradiation configuration improves dose uniformity and precision of dose measurement. Irradiation is an important tool with many applications in agriculture, including control of bacterial infection, phytosanitary treatments to kill insect pests on food products, and sterilization of insects for a pest control strategy called Sterile Insect Technique. Irradiation of corresponding samples such as insects, nuts, or seeds is typically accomplished by placing them in a container close to a radiation source, and those at the edges thus experience higher doses than those towards the center. ARS researchers in Albany, California, have developed an irradiation configuration in which all samples as well as appropriate radiation measuring devices (dosimetry) are confined to the surface of a rotating wheel under an x-ray source. Since the samples and dosimetry all follow the same path through the x-ray field, variation of x-ray dose among samples is very low and precise dose measurement is possible. While not appropriate for every size/shape of sample, this technology provides a valuable tool for precise and uniform dosing of a large variety of sample types.
2. Differences in the phenolic composition of fermented and non-fermented jaboticaba fruit powder. Jaboticaba is a fruit native to Brazil that is used in food or fermented beverages. Since Jaboticaba spoils rapidly it is often used for juices, jams, liqueurs, distillates, wine and ice cream to reduce post-harvest losses. ARS researchers in Albany, California, performed comparative analysis of total phenolic content in fermented versus non-fermented jaboticaba pomace. Fermented pomace (after wine production) contained higher levels of the phenolics quercetin and myricetin, compared to pomace obtained after juice extraction (unfermented). Fermented pomace may be added to food products to provide color (anthocyanins), increase antimicrobial properties, and possibly reduce the risk of diabetes, obesity and chronic obstructive pulmonary disease.
3. Identification of the first member of a new food allergen family. Characterization is needed for a better understanding of the allergenicity of food allergens and their cross-reactivities. ARS researchers in Albany, California, have identified a new almond allergen. This novel allergen has antimicrobial activity and defines a new family of allergenic food proteins. The reported result and future studies of the allergenic properties of other members of this new food allergen family from other foods may help increase understanding of the allergenicity of tree nut proteins.
Review Publications
Liang, P., Haff, R.P., Zayas, I.Y., Light, D.M., Mahoney, N.E., Kim, J. 2019. Curcumin and quercetin as potential radioprotectors and/or radiosensitizers for x-ray-based sterilization of male navel orangeworm larvae. Scientific Reports. 9:2016. https://doi.org/10.1038/s41598-019-38769-3.
Milczarek, R.R., Liang, P., Wong, T., Augustine, M.P., Smith, J.L., Woods, R., Sedej, I., Olsen, C.W., Vilches, A.M., Haff, R.P., Preece, J.E., Breksa, A.P. 2019. Nondestructive determination of the astringency of pollination-variant persimmons (Diospyros kaki) using near-infrared (NIR) spectroscopy and nuclear magnetic resonance (NMR) relaxometry. Postharvest Biology and Technology. 149:50-57. https://doi.org/10.1016/j.postharvbio.2018.11.006.
Watanabe, S., Matyska-Pesek, M.T., Berrios, J.D., Takeoka, G.R., Pesek, J.J. 2018. HPLC/ESI-TOF-MS identification and quantification of phenolic compounds in fermented/non-fermented Jaboticaba fruit (Myrciaria jaboticaba (Vell.) O. Berg). International Journal of Food Sciences and Nutrition. 3(5):105-109. https://doi:10.22271/food.2018.v3.i5.21.
Bilbao-Sainz, C., Sinrod, A., Powell-Palm, M., Dao, L.T., Takeoka, G.R., Williams, T.G., Wood, D.F., Ukpai, G., Aruda, J., Bridges, D.F., Wu, V.C., Rubinsky, B., McHugh, T.H. 2018. Preservation of sweet cherry by isochoric (constant volume) freezing. Innovative Food Science and Emerging Technologies. 52:108-115. https://doi.org/10.1016/j.ifset.2018.10.016.
Takeoka, G.R., Dao, L.T., Elkahoui, S. 2018. Phenolic composition of grape pomace skin of four grape cultivars. International Journal of Food Sciences and Nutrition. 3(6):246-249.
Hoffman, J.F., Bassinello, P.Z., Filho, J.M., Elias, M.C., Takeoka, G.R., Vanier, N.L. 2018. Volatile compounds profile and cooking quality characteristics of brazilian aromatic rice genotypes. Cereal Chemistry. 96(2):292-301. https://doi.org/10.1002/cche.10121.
Che, H., Zhang, Y., Lyu, S., Nadeau, K., McHugh, T.H. 2018. Identification of almond (Prunus dulcis) vicilin as a food allergen. Journal of Agricultural and Food Chemistry. 67(1):425-432. https://doi.org/10.1021/acs.jafc.8b05290.
Jin, T., Brefo-Mensah, E., Fan, W., Zeng, W., Li, Y., Zhang, Y., Palmer, M. 2018. Crystal structure of the Streptococcus agalactiae CAMP Factor, and insights into its membrane-permeabilizing activity. Journal of Biological Chemistry. 293:11867-11877. https://doi.org/10.1074/jbc.RA118.002336.
Liu, Y., Fan, Y., Gao, L., Zhang, Y., Yi, J. 2018. Enhanced pH and thermal stability, solubility and antioxidant activity of resveratrol by nanocomplexation with a-lactalbumin. Food and Function. 9:4781-4790. https://doi.org/10.1039/c8fo01172a.
