Source: UNIV OF HAWAII submitted to NRP
POSTHARVEST QUALITY AND SAFETY IN FRESH-CUT VEGETABLES AND FRUITS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
Reporting Frequency
Annual
Accession No.
0220879
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
S-294
Project Start Date
Oct 1, 2005
Project End Date
Sep 30, 2010
Grant Year
(N/A)
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
Consumption of a wide variety of sufficient fruits and vegetables is being encouraged at a national level to prevent chronic diseases and some types of cancer. Although frequency of fruit and vegetable consumption has changed little from 1994 to 2005, sales of minimally processed fruit and vegetables appear to be increasing. A minimally processed (MP) product is defined as the handling, preparation, packaging and distribution of agricultural commodities in a fresh-like state, and usually involves cutting or/and trimming to provide ready-to-eat forms. However, one of the problems of minimally processed fruits is the physical alteration of the fruit can promote accelerated ripening and softening of the tissue. Other concerns include contamination and growth of microorganisms. By experimenting with various processing techniques, such as treatment of the papaya flesh with calcium compounds to strengthen cell walls and dipping cut fruit in a hot water bath, this study may find a method to delay the ripening process, increase firmness of papaya flesh, and delay microbial growth on the cut surfaces. A successful process would allow papaya farmers and food distributors to have a technique to supply a quality ready-to-eat fruit product to consumers with a reasonable shelf life in stores and supermarkets.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
7121020110050%
7121030110050%
Goals / Objectives
GOALS: OBJECTIVES: #4) Standardize methods for recovering pathogenic and spoilage microorganisms from intact and fresh-cut produce including tree nuts. #5) Evaluate and control unintentional and intentional microbial contamination of intact and fresh-cut produce. EXPECTED OUTPUTS: Using various processing treatments to control intentional and unintentional microbial contamination of fresh-cut produce can produce a number of unintended consequences on the fruit themselves, such as accelerated ripening and senescence. For example, cutting and dicing of fresh-cut produce can lead to more rapid softening of the tissue and microbial contamination and growth on the cut surface. Minimal processing and calcium treatment of cut papayas (as an example of a climacteric fruit) will be used to evaluate texture change and microbial growth of a cut (and ready-to-serve) fruit. This study will determine whether or not certain processing treatments can extend the shelf life and sensory characteristics of this fruit.
Project Methods
Papayas will be purchased from a local commercial source, washed, cut into ready-to-eat pieces, treated with various calcium solutions, packed into vacuum pouches, placed in a hot water bath, cooled, and then stored at 4 degrees Centigrade for at least 10 days. Samples will be removed periodically and the papaya texture will be analyzed using a commercial texture analyzer. Total aerobic microorganism growth (total plate count) will be determined. Different firmness measurements will be evaluated using analysis of variance and microbial growth will be plotted against number of days in storage. Efforts for sharing new information will be through scientific publications and working with local food processors providing ready-to-eat foods. Thus far, there are no reports on a combination of heat and calcium treatments on cut papaya pieces. This project will be successful if texture of the fruit is maintained for at least 10 days, microbial counts are low, and there is a minimum of papaya flesh damage during post treatment storage.

Progress 10/01/05 to 09/30/10

Outputs
OUTPUTS: Growing papayas for export and for local commercial sales will often result in a percentage of the harvested fruits that are disfigured and scarred on the surface. The internal flesh of these papayas have the same quality as normal fruit, yet these blemished fruits cannot command as high a price as the normal fruit and are often sold below cost of production or given away. If these lower quality fruits could be minimally processed (MP) and provided to consumers in a ready-to-eat form, papaya growers will be able to recover a higher amount of their investment costs. Minimal processing (heating and calcium treatment) was examined for maintaining fresh quality texture and appearance. Papaya fruits (Kapoho variety) harvested at color break were kept at room temperature until they were ripened to three-quarter yellow skin stage and then heat treated to a temperature approved for the elimination of fruit flies. The papaya fruits were then cooled and processed (peeled, deseeded, trimmed and halved) to yield four papaya chunks per fruit. Pieces were then soaked in 1% calcium gluconate and lactate solutions for five minutes, drained and then individually packed in Ziplock bags, and stored at 4 C for 14 days. The texture of four sample groups (control, heat treatment alone, calcium lactate treatment, and calcium gluconate treatment) was measured during the storage period. Total aerobic micro-organism growth (TPC) were also conducted on papaya pieces after 5 and 10 days. PARTICIPANTS: Individuals: Wayne Iwaoka, project investigator Partner organizations: none Collaborators: none Training or professional development: one student TARGET AUDIENCES: Target audience: The target audience would be farmers, whole sale distributors, or food processors that would likely have second grade or cull papaya fruit. Efforts: Informal talks with papaya growers at farmers markets about the problems with minimal processing of papaya fruits using heat and/or calcium treatments to extend quality and shelf life of cull papayas. PROJECT MODIFICATIONS: This Project Investigator joined this research project on January 14, 2010. The results of this study were somewhat unexpected and do not appear to have too much promise. Thus, this research project is intentionally being terminated early.

Impacts
Results indicate that the heat and calcium treatments caused the texture of the papaya flesh to remain firmer for a longer period of time than the pieces with no heat or calcium treatments, however, these treatments also produced papaya pieces that had very large variations in the texture. Some texture data collected had to be eliminated because some papaya pieces had texture hardness at least five times higher than some of the other papaya pieces that appeared to be of the same degree of ripeness. While heat and calcium treatments appeared to be effective in maintaining flesh texture in some of the pieces, some fruit pieces also developed translucency during the storage period while others did not. In another study to prevent translucency, the MP papayas were heated at a higher temperature for a shorter period of time. The results showed that this processing technique stopped the ripening process and all the papaya slices were still very hard by day 10. It appears that the papayas used in this study and ripened to the same degree of skin color still had some variation in flesh firmness before minimal processing. The results of this study suggest that minimally processed papaya slices subjected to heat and calcium treatments have minimal microbial growth after 10 days and also produced papaya pieces that continued to have inconsistent texture as well as have translucent flesh in some but not all of the pieces. Because of the variability of flesh texture before and after minimal processing, this technique does not appear to be feasible for use with cut papaya slices.

Publications

  • No publications reported this period