EVALUATION OF NUTRIENT CONTENT OF HAWAII-GROWN AVOCADOS AND IDENTIFICATION OF OPTIMAL HARVEST PERIOD

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1004490
• Project Start Date: Dec 15, 2014
• Project End Date: Sep 30, 2018
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIV OF HAWAII
3190 MAILE WAY
HONOLULU,HI 96822

Performing Department
Human Nutrition, Food & Animal Sciences

Non Technical Summary
Avocados are an important agricultural crop in the state of Hawaii; however the majority of avocados consumed in the state are imported from the US Mainland or international locations. Hawaii-grown avocados have desirable sensory attributes that are linked to oil content. Oil content increases as avocados mature. Previously, the optimal harvest window to maximize oil content for the Sharwil cultivar was determined (Chen et al. 2009). This work needs to be replicated with additional cultivars, so avocado growers know when to harvest the highest quality fruit. The aim of the current project is to analyze six common avocado cultivars at to identify the oil content. This work will be completed during two sequential growing seasons to better understand the seasonal variation in oil content. The samples will also be analyzed for moisture, protein, dietary fiber, and carbohydrate,antioxidant content. This project will also expand the nutritional dataset with additional avocado cultivars that are currently in production in Hawaii. This data developed by this project will address priority area #2: Hawai'i's Diversified Tropical Crop Systems for Sustainability and Competitiveness by educating the avocado growers on optimal harvest period, thus allowing them to harvest the highest quality fruit.

Animal Health Component

(N/A)

Research Effort Categories

Basic

90%

Applied

(N/A)

Developmental

10%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
204	1099	1010	20%
701	1099	1010	80%

Knowledge Area
204 - Plant Product Quality and Utility (Preharvest); 701 - Nutrient Composition of Food;

Subject Of Investigation
1099 - Tropical/subtropical fruit, general/other;

Field Of Science
1010 - Nutrition and metabolism;

Keywords

avocado

hawaii

nutrient content

Goals / Objectives
The aim of the current project is to analyze six common avocado cultivars for nutrient analysisto better understand the variation in oil content. The samples will also be analyzed for moisture, protein, dietary fiber, carbohydrate, and antioxidantcontent. This project will also expand the nutritional dataset with additional avocado cultivars that are currently in production in Hawaii.

Project Methods
Fruit collection and analysisFive mature fruits will be harvested during the typical harvest season, specific to each cultivar. Fruit will be collected at four different times during the harvest season to determine how harvest time affects nutritional value. Fruits will be harvested by PI, co-PI, and/or grower (if on private farm). Nutrient analyses will be conducted using AOAC methods in the Stewart Lab. Whole weight, edible portion, seed weight, and skin weight will be measured for each fruit. Edible portion from each avocado will be homogenized. Each homogenized avocado will be lyophilized using a 36-hour drying cycle at -40°C at 720 Torr (VirTis Virtual 50xl, SP Scientific, Warminster, PA). Moisture content will be calculated based on the difference between the fresh weight and the lyophilized weight. Crude oil will be measured in each individual avocado harvested to identify within-cultivar variation. The remaining cultivar x harvest samples will be pooled for further analysis. Individual fatty acid methyl esters (FAME) will be extracted via AOAC method 969.33 (AOAC International, 2011). Decane will be added to each sample during extraction as an internal standard. Individual FAME will be quantified using an HP 5890 gas chromatograph with flame ionization detector (Santa Clara, CA). An RT-2560 (biscyanopropyl polysiloxane) capillary column (100 meter, 0.25 ID, 0.2 micron df, Restek Inc, Bellafonte, PA) will be used to quantify FAME. Initial oven temperature was 100C, rising 1.5C/min until 250?C was reached. The sample volume will be 1 microliter with an inlet temperature 250C and detector temperature 250C. The following flow rates will be used: helium (on-column flow rate of 0.6 mL/min, make-up flow 39.4 mL/min), hydrogen (40 mL/min) and air (440 mL/min). Peak integration will be conducted with ChemStation software (Agilent Technologies, Santa Clara, CA). Individual FAME concentrations will be determined relative to the decane concentration, based on standard curves. Protein content will be determined using the Kjeldahl method (AOAC method 2001.11) (AOAC International, 2011). Dietary fiber content will be determined using AOAC method 991.43 (AOAC International, 2011). Total mineral content will be determined via ashing. Carbohydrate content will be determined by difference. Energy content will be calculated using Atwater factors. Each sample will be run in duplicate. Harvest from years 2-3 will be replicated during years 3-4. Climate data (monthly rainfall, mean monthly temperatures, wind) will be obtained from NOAA-NWS reporting station nearest to harvest locations.Data analysis and publicationThe data developed in this project will be submitted for publication in a peer-reviewed scientific journal such as the Journal of Agriculture and Food Chemistry. The data will be disseminated to the stakeholders and local community members through a CTAHR Extension publication and presentations at the Hawaii Tropical Fruit Growers Association annual meeting, the Hawaii Avocado Association meeting, and at the Avocado Festival in Kona. Avocado producers will also be surveyed regarding their knowledge and implementation of optimal harvest period for their avocados.

Progress 12/15/14 to 09/30/18

Outputs
Target Audience:*Presentation at the Hawaii Avocado festival in Feb 2015. Gave a presentation to the Avocado growers and also provided community outreach at an educational display. *Presentation in the Hawaii Tropical Fruit growers Association's Annual meeting Sept 2015. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?*One MS student was trained and graduated in the field of Nutritional Science and Thesis was accepted as successful and published. How have the results been disseminated to communities of interest?*A presentation was made in the Hawaii Avocado festival in Feb 2015 and highlighted the nutritional value of different varieties of avocados and their functional values in human nutrition and health. *Presentation in the Hawaii Tropical Fruit growers Association's Annual meeting Sept 2015. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? *PD met with Avocado growers to determine the availability of different varieties of avocado for research. *Avocado samples were collected and processed for nutrient analysis. *Altogether 10 Avocado cultivars (six Hawaii-grown and four Cameroon-grown) were analyzed for their detailed nutrient profile including proximate nutrient (moisture, protein, dietary fiber, carbohydrate), fatty acid profile and antioxidants.

Publications

• Type: Theses/Dissertations Status: Submitted Year Published: 2017 Citation: Kai, J. 2017. Nutrient Composition of Avocados Grown in Hawaii and Cameroon. MS Thesis; Department of Human Nutrition, Food, and Animal Science; University of Hawaii at Manoa; Honolulu, Hawaii.

Progress 10/01/16 to 09/30/17

Outputs
Target Audience:Health and nutrition professionals. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?One MS student was trained and graduated in the field of Nutritional science and Thesis was accepted as successful and published. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?Publish the project findings as peer-reviewed journal article.

Impacts
What was accomplished under these goals? Altogether 10 Avocado cultivars (six Hawaii-grown and four Cameroon-grown) were analyzed for their detailed nutrient profile including proximate nutrient (moisture, protein, dietary fiber, carbohydrate), fatty acid profile and antioxidants.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: J. Kai, J.P. Bingham, A. Franke, G. Agbor, M. Stewart, and R. Jha. 2017. Nutrient profile of Hawaii and Cameroon grown avocados (Poster). In: Proceedings of 29th Annual CTAHR/COE Student Research Symposium (April 7-8, 2017), Honolulu, HI, USA.

Progress 10/01/15 to 09/30/16

Outputs
Target Audience:*Avocado farmers, health and nutrition professionals, consumers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?*One MS student is being trained in the field of Nutritional science. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?*Nutrient analysis of collected Avocado samples. *Present findings in a professional meeting and share information with Avocado farmers and other stakeholders. *Completion of MS degree of the graduate student being trained through this project and publish findings as Thesis.

Impacts
What was accomplished under these goals? *Avocado samples were collected and processed for nutrient analysis.

Publications

Progress 12/15/14 to 09/30/15

Outputs
Target Audience:Hawaii tropical fruit and avocado growers. Consumers in Hawaii. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?PD education avocado growers on the nutritional value of their product (hawaii-grown avocados), basee on existing data (Feb 2015). How have the results been disseminated to communities of interest?Presentation at the Hawaii Avocado Festival, February 2015. We gave a presentation to growers and also provided community outreach at an educational display. Presentation at the Hawaii Tropical Fruit Growers Association annual meeting, September 2015 What do you plan to do during the next reporting period to accomplish the goals?We will begin nutrient analysis on avocados in the 2016 growing season. We will present our preliminary finding at the Hawaii Tropical Fruit Growers Association meeting in September 2016.

Impacts
What was accomplished under these goals? PD met with avocado growers to determine availability of avocados for research.

Publications

• Type: Websites Status: Other Year Published: 2014 Citation: Stewart, M. 2014. Updates to content on homepage, advertising upcoming avocado-related events such as the Annual Avocado Festival in Kona. http://choosehawaiiavocados.org/