Development of ready-to-cook frozen taro (Colocasia Esculenta) in the Northern Marianas Islands

Final Report for FW10-033

Project Type: Farmer/Rancher
Funds awarded in 2010: $14,480.00
Projected End Date: 12/31/2011
Region: Western
State: Northern Mariana Islands
Principal Investigator:
Asapmar Ogumoro
Marianas Farmer/NMC-CRESS
Expand All

Project Information

Abstract:

Our project aimed to help taro farmers and invite other local farmers to grow more taros for the community. Taro is a nutritious underutilized crop that is barely seen in our markets today. The project experimented with several planting techniques and methods to produced healthy and good yields with a marketable appearance. The project was conducted into two phases; first, to conduct experiments with sustainable planting techniques and methods for taro. Second, to study and create the development of a value-added product using the taro grown during the experiment period and to extend the shelf-life of taro.

Introduction

One of the first highlights that emerged from the project was the nutritional analysis of the final product “Ready-to-Cook Frozen Taro.” Our samples were sent to a laboratory in Gwan Ju, Korea. We included a one-month taro sample, which was grown during the dry season, along with a six-month-old frozen sample, which was grown during the rainy season. We compared the differences in the nutritional value as shown in Table 1.

We achieved favorable results from the experiment in the project. We were able to produce taro with better nutritional value during the rainy season under the sustainable planting techniques and methods.

Another successful result in our experiment was the appearance of the product. We were skeptical about the changing appearance of the taro corms because of freezing temperatures and storage time. Our goal was to vacuum-pack the corms for six months to evaluate. Observations on most packages showed minimal change in vacuum-pack bags during the sixth month. The taro corms were able to maintain their rich pink color that is a marketable appearance in the CNMI. We also tested taros in standard zip-loc bags, however the marketable value lasted a short time of two weeks due to freezer burns. We discontinued this study using zip-loc bags for health and safety purposes.

During the extension presentation, we provided three different frozen taro samples: 1) Fresh taro, 2) three-month frozen taro, 3) six-month frozen taro. Each sample was boiled in different pots for the same amount of time and served in different containers. The participants were given simple surveys to answer regarding frozen taro sample taste testing. We obtained the results and responses from all farmers, community members as well as college extension staff. The taste results were very surprising since many testers could not tell much difference between the samples. This informed us that the low-cost value-added product is highly acceptable. A few testers informed us about another possible achievement, as they could not taste any "itchiness" from the frozen samples, which is was a good result from the experiment.

Overall, we found the project to be very helpful in extending the shelf-life of taro during and after harvesting seasons. In addition, we learned that the product was exportable to neighboring islands in this value-added state. The experiment was successful since the responses from the local farmers were great as they enjoyed the taro samples and had plans to incorporate sustainable methods when growing taro for the community.

Project Objectives:

The objectives of this project are

(1) to provide small farm businesses with an alternative method and the interest to venture back into producing nutritious and favorable taro for the community,

(2) to conduct a study on how to extend the shelf-life of taro as well as technology to package taro to preserve its taste and nutritional value during non-harvesting season (approximately seven months),

(3) to study how the favorable taro responds in frozen packages based on appearance, taste and nutritional value,

(4) to disseminate all information on planting, harvesting, processing, packaging and sampling collected from different months, and

(5) to promote an alternative method for taro farmers,including the confidence in producing more taro for the community during the off-season.

Cooperators

Click linked name(s) to expand/collapse or show everyone's info
  • Dr. Jang Ho Kim
  • Asapmar Ogumoro

Research

Materials and methods:

Planting taro during its favorable season in the CNMI:

The initial planting and timing of the taro were the most important factors to begin the project. The first objective was to plant the taro at least one or two weeks before the first heavy rainfall, which indicates the start of the rainy season. This allows farmers to properly prepare and bed taro in dry soil conditions. Based on weather data, we planted the taro seedlings during the last week of May to catch the rainy season, which was expected to begin in early June. By doing this, the taro seedlings would be naturally irrigated with fresh rainwater rather than the community aquifer.

The placement of plant and row spacing were critical parts of the planting technique. The taro seedlings were planted one foot apart in each row and each row was three feet apart. This allowed the taro to form a tight canopy above to suppress weed growth below. In addition to the close spacing, it allowed the taro patch to brace well during strong winds, which usually occurs during the rainy season. This allowed the taro corms to grow well and straight. Being able to grow straight corms was important for marketability, especially during the peeling process. Crooked corms would be harder to peel manually and would take more time to prepare into a product.

On the experimental field, we created 10 rows containing 50 pieces of taro on each row, totaling 500 pieces of taro. We allowed the taro to grow for six months before harvest.

During the growth stage, we reduced the amounts of fertilizer by half compared to the traditional application, since the taro was showing healthy signs of growth during the first four months of the rainy season. Traditionally, farmers would apply .5 - .10 ounces of 16-16-16 during the second and fourth month of the taro growth. During this experiment, we applied .5 ounces of 16-16-16 during the second month of the taro growth. We were skeptical about our yields with skipping the second application of fertilizer but decided not to apply since the taro leaves were dark green and the height was well above four feet in height. These indicated that the taro plant grew healthy without faults.

Between the third and fifth month of the taro stage, we would usually see stress signs of taro blight or mosaic, which is common during the dry season. However, during this rainy season, we did not see any sign of these diseases affecting the taro growth. In addition, we could not find any aphids attaching themselves to the taro leaves. This might have been due to the constant rainfall and wind making it difficult for aphids to mobilize under wet conditions. Aphids are a common pest on taro in the CNMI and are aggressive and prevalent during the dry seasons. This was another important observation that was shared with participants during the presentations and field days.

After harvest and cleaning of 500 pieces of taro corms, the total weight of taro was 624 lbs. In the experimental field, an average of 1.2 pounds of taro corm was produced. It had been expected that yields of 400-450 pounds or .9lbs per taro corm would be produced. Based on these results, growing taro during its favorable season with modified techniques such as spacing and timing produced better taro corm yields.

Developing a Value-Added Product “Ready-to-Cook Frozen Taro”:

Farmers in the past have struggled to sell taro during the harvesting season because of excess supply during the months of November and December. Taro is commonly sold in its raw form and has a shelf life of three to ten days based on storing conditions. As a result, many nutritious corms are wasted, and farmers fall short on their potential profits. With this history, farmers have minimized their taro acreage and production in the CNMI.

The second experiment following the taro planting method aimed to extend the shelf life of any surplus taro throughout the non-harvesting seasons. The taro harvested from the experimental field was processed by peeling of the skin and vacuum packaging the corms, which was later placed in regular household freezers at 20° – 30° F. Each packaged sample weighed between seven to 10 pounds each.

Before testing the vacuum-packed taro samples, we asked taro consumers how they typically prepared and consumed taro. Before the taro corm is consumed, customers would wash and peel off the exterior (skin), cut into two-inch cubes of the raw corm and boil in water for several minutes. The taro corm samples were prepared without boiling. We allowed our testers to boil the samples to their preference. All samples were vacuum-packed tightly to minimize oxygen levels and moistures in each bag.

In this experiment we tested the taste, appearance and nutritional value of the prepared product at different stages of one-, three- and six-months. We observed several changes of appearance in a few samples due to possible failures during the packaging. Some packaged samples were showing small signs of freezer burns, while others did not. This could have been a result from poor vacuum or improper sealing during the vacuum packaging. Despite the faults, many packages were able to maintain a marketable appearance. A marketable appearance includes pink color and firm texture. We were able to achieve a marketable appearance even after six months of frozen storage by using one of the two vacuum packaging devices, two different seal bags and standard home freezers.

We conducted several taste testings and project presentations at several locations such as farm site, hotel and restaurant. Local farmers and community members were invited to attend. Before providing the guest with cooked taro samples, we shared the purpose and background of the project’s experiment. For the taste-testing experiment, we conducted a blind taste testing. We did not tell guests the actual age of the three samples as they were instructed to select the age based on the taste. Each participant filled out a simple survey form. (See Survey 1)

Survey 1. Sample taste-testing survey

1. “Which sample do you think is the one-month taro?”
2. “Which sample do you think is the six-month taro?”
3. “Which sample did you think had the best taste and appearance?”

Overall results indicated that less than 50% of the participants were able to choose the correct age of the taro samples. Furthermore, 85% of the participants answered they enjoyed the taste of frozen taro over the fresh taro (Question # 3). The participants also appreciated and noticed that the post-harvest and valued added technique “Ready-to-Cook Frozen Taro” can be seen as favorable and acceptable product in our local markets.

In addition to these results, many participants noticed no sign of itching during consumption of the taro that was frozen. This was an unexpected finding. This itchiness could have been eliminated during the freezing process. Taro, which contains oxylant crystals, may cause some light itching sensations during consumption. However, no signs of itching were present during the sampling of three to six month frozen taros. This was a beneficial finding and could be examined for future studies.

Dasan Institute of Life & Science Co. located in Gwang Ju, South Korea conducted the project’s nutritional analysis. Obtaining a nutritional analysis was a difficult task. Our island does not have any laboratory capable of conducting a nutritional analysis on food items. Another difficultly was sending samples in its frozen state. For these reasons, the product actually had to be hand carried into the Seoul, Korea and mailed to the laboratory. Due to this situation, we decided to send two frozen samples, which were a one-week old taro and a six-month old taro respectively. The one-week old taro was grown during the dry season, and the six-month old taro was from the actual experimental field. The results showed significant differences. We found an increase of beneficial nutrition such as protein and higher carbohydrates levels. Taro is also known to contain a great source of fiber, however the laboratory was unable to determine that specific result. As a consumer, we observe that the taro grown during its favorable season was much more nutritious than the taro grown during the dry season. This was another favorable finding that emerged from both the planting method and the value-added process.

(See Table 1)

Due to the difficulties in purchasing and shipping the proper peeling machine with uniform quality, we decided to focus on different devices and manual peelers that come in various shapes and sizes. Manual peelers allowed us to peel off unwanted areas, leaving behind the marketable interior of the corm. We later realized how important manual peelers were since peeling too much may affect the value of the corm since it is mainly sold by weight. Manual peelers seemed to be an effective tool due to its agile functions and maneuverability. Manual peelers were also easier for farmers to obtain and afford here in the CNMI. After experimenting with manual peelers, we found that stainless steal peelers with 2-2.5” blades in width worked the best for taro corms. Stainless steal peelers were also easier material to clean and rinse off residue after peeling one or more corms.

Research results and discussion:
Benefits or Impacts on Agriculture

One of the benefits from this project is to use sustainable planting methods such as growing taro during the appropriate season, which is the rainy season from early June to late November. The rainy season provides a fresh and adequate supply of water needed for proper taro corm growth and yield. Growing taro during the dry season requires large amounts of irrigation, which will be tapped from city lines and wells, which is supported from our island’s aquifer. A majority of small and commercial farms in the CNMI obtain their water source from city lines and water containers supplied by ground water. Saving our community's water supply and utilizing our consistent rainy season is beneficial for both our community and taro plantations here in the CNMI.

Second benefit made during the rainy season was the low levels or absence of aphids in the taro patch. This was another highlight of the project and savings since the purchase of insecticides was not necessary. Malathion 50 Plus is a common insecticide here in the CNMI used to suppress aphids and other field pests. Aphids mainly feed on the taro leaves, which could weaken or stunt the taro growth. This may reduce the potential yield and profits. A 10 ounce bottle of insecticide such as Malathion 50 Plus would range from $20-$30. In the CNMI, small farms may spend $100 to $200 to suppress aphids if planting taro during the dry season. However, a potential savings may be made if the farmer chooses to plant during the rainy season. In addition to that, less labor required to apply the insecticide will become an additional savings.

Third benefit in this sustainable practice was the labor saved that is needed to weed out unwanted vegetation in the taro patch. Varieties of grass and weeds are seen here in the CNMI soils. However, grass and weeds tends to grow slow or stagnate under shady or dark conditions with out any sunlight. By planting the taro close together, one foot apart in rows spaced three feet apart, the taro was able to create a tight canopy with its large green leaves. The taro was able to grow fast enough to suppress and out-compete weeds. Although there were some weeds present in the patch, it did not affect the growth or damage the crop.

During the dry season, weeding is a laborious job and may take 10 to 15 hours to complete in a field of 10-20 rows. Weeding is usually done during the same time of fertilizing. It is recommended that farmers weed their patches twice throughout the lifespan of the taro. However, we found that labor can be saved if the initial planting is aligned and timed properly with the rainy season. By spacing the seedlings one foot apart and the rows three feet apart, a quick taro canopy will sufficiently emerge to prevent weed growth. By doing this, farmers would either weed out small portions of the taro patch or may not have to weed out at all.

Forth benefit to the farmer and community is we found the differences in nutritional value between the taro grown during the dry and rainy season. Taro grown during the rainy season is not only cheaper for the farmer due to savings, but also healthier for the community. The nutritional value of the taro grown during the rainy season had a higher content of protein and beneficial carbohydrates. The taro grown during the rainy season had twice the amount of protein than the taro grown during the dry season. (See Table 1) The community will be consuming a healthier source of taro when farmers grow during the rainy season.

Fifth benefit of this project was in the value-added product. The project decided to look into low-cost equipment and materials that could create a marketable end product containing the taro corm. The project also focused on obtaining equipment that is available on island and affordable for small and large farms in the CNMI. Purchases of equipment such as vacuum packaging machines, sealer bags, peelers and freezers were used to test and develop a value-added taro product. Farmers were able to see the equipment and tools used to add value on the fresh taro and extend the shelf-life of taro, which could be available to the market for at least six months, depending on the quality of the packaging. Farmers and participants were pleased with the value-added product, showing our nutritional results and taste-testing the samples. This provided farmers with an alternative method to having taro available for their customers during the off-season.

The sixth benefit to savings and the environment is the less or no use of fertilizer. The common fertilizer used during dry and rainy seasons include 16-16-16 or 46-0-0. Farmers usually apply 46-0-0 during the dry season to strengthen the taro leaves and corm growth. However, based on our observations, we noticed how well the taro growth was responding to the rainy season and decided not to apply 46-0-0. Usually, farmers would make two applications of fertilizer; one during the second month and another during the fourth month. However, in this experiment, we decided to apply .5 ounce of 16-16-16 during the second month. (See Table 2) During the fourth month, the taros’ dark green leaves and four feet height were showing sign of good health. Based of these results, it seemed unnecessary to conduct the second application of fertilizer. By doing this, we reduced our applications of fertilizer by half. For the experimental field, which had a total 500 pcs. of taro, we saved 25lbs. of 16-16-16 by not applying the traditional second application. We were not optimistic at first, but surprised that we came out with a good yield of 624lbs. During the dry season, many farmers would expect a lower yield of 400-450 lbs. even after applying 16-16-16 during second and fourth month of the taro growth. This observation may help farmers get additional savings from using less fertilizer and may prevent excess fertilizer entering the natural ground water.

(See Table 2. Labor Analysis)

Participation Summary

Educational & Outreach Activities

Project Outcomes

Project outcomes:

1. Venturing into value-added products to extend the shelf-life of their perishable goods including under utilized crops such as taro and traditional root crops.

2. Being cautious with savings to increase potential profits by lowering their irrigation usage, purchases of pesticides and applications of fertilizer.

3. Growing crops during its favorable seasons such as taro to improve nutrition content with natural water supply.

4. Saving valuable operation time by incorporating proper planting techniques, which can improve yield and reduce labor costs.

Recommendations:

Potential Contributions

Reactions from Producers

During the presentation, several farmers were skeptical about the new planting techniques and were curious to learn more. They were invited to visit the actual experimental site and were pleased to see the real-life upcoming patches growing under the same planting methods and techniques. Conducting field day visits to the actual experimental site aimed to boost farmers’ confidence in growing taro during the favorable season. They were able to see the quality of the taro and effectiveness of incorporating sustainable practices into their operations.

Some farmers were also interested in obtaining the same or similar tools used to create the value added product with taro. They learned how to extend the shelf-life of the taro corms and other root crops. They asked for advice on where to purchase this equipment, and we were pleased to share them the additional information.

Many of the participants enjoyed the test-tasting experiment and were surprised that they couldn not taste the difference between the fresh taro and the sixth month old taro. Several guests asked for additional samples to examine and still could not taste the difference.

Some experienced taro consumers were startled on how they could not taste any light itchiness on their lips. They suspected that this resulted from the long freezing period.

Some participants, who were not producers or farmers, appreciated the purpose of the project for its actions in practicing sustainable agriculture methods and promoting similar organic methods to other farmers in the community.

Future Recommendations

Taro is a root crop that grows six to eight months before maturity and harvest. Any researcher and farmer interested in conducting or performing a field study on taro may need more than the required contract year to accomplish a complete study of the crop.

Any researcher or farmer interested in freezing root-crops, specifically taro, may want to investigate how chemical changes occur during the freezing process. In this project, we could not examine how or when the taro’s oxylant crystals had dissipated during the freezing process. Thus, this could be a potential project in the future.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.