Sylvia WillisHOS 5085C

November 20181

Quality Deterioration of Whole Seedless Watermelon Versus

Fresh Cut Pieces

Thank you for joining me today to talk about our Post‐Harvest HOS 5085C class lab projects. Today I will be presenting about my research on the quality deterioration of whole seedless watermelon versus fresh cut pieces. 

1

Overview• Introduction

•Objectives and Working Hypothesis

•Materials and Methods

•Measurements and Assessments

•Conclusions

2

I will begin with a quick introduction about why this research is necessary, followed by my objective and working hypothesis for this experiment. Next, I will go into the materials and methods, measurements and assessments, and finally ending with my conclusions drawn from this experiment. 

2

Introduction•Seedless watermelon is highly consumed fruit, especially during the summer time

•Since watermelon is a large fruit and difficult to cut, many have resorted to buying fresh-cut pieces

•Fresh-cut watermelon account for 10% of watermelon sales

•The increased demand is present, but proper storage and shipping is necessary

3

Watermelon, Citrullus lanatus, is a commonly cultivated fruit. Florida itself is ranked first nationally in production, with north to north‐central Florida having almost 36.6% of harvested acreage. Seedless watermelon leads the market and consumer demand for this product has highly increased. Seedless watermelon is consumed mostly in the summer months, but is available all‐year‐round.  Watermelon is a sweet, juicy fruit but consumers can deter from buying a whole melon due to the difficulty in cutting it and the consumer may not want the entire melon. As a consumer, we do not want to buy something that will go to waste if we cannot eat it all before it goes bad. Due to this and many other aspects, fresh‐cut watermelon production has become more common and now accounts for 10% of watermelon sales. Consumers are willing to spend more for the convivence of fresh‐cut melon, but proper storage and shipping is necessary to maintain consumer quality. (National Watermelon Promotion Board, 2002)

3

Introduction•Product needs to maintain visual and taste appeal•Major factor in consumer purchase decisions

•However, once the fruit is cut, it will begin to deteriorateoLoss of textureoLoss of coloroLoss of sweetness

•Post-harvest life of watermelons reduces significantly once cut

• Important to find the best methods for providing convivence to the consumer but not losing overall quality

4

Quality is an important factor when purchasing fresh‐cut watermelon. The consumer will buy a product that has high quality both internally and externally. However, once the watermelon is cut, loss of quality is increased. The fruit will become injured and result in unfavorable qualities such as loss of texture, color, and sweetness. The shelf‐life of the cut pieces also decreases in a matter of hours. If a consumer is spending more money for the fresh‐cut product, it is important to provide high quality product. (Sargent et.al., 1996). 

4

Objectives

The objective of this experiment is to compare the quality and deterioration of fresh cut seedless

watermelons to whole fruit stored watermelons in 5˚C and 15˚C via a cooler.

5

The objective of this experiment is to compare the quality and deterioration of fresh cut seedless watermelons to whole fruit stored watermelons in 5˚C and 15˚C via a cooler. Overall, is it better to buy fresh cut watermelon or buy whole fruit? Another question to consider would be is it better to buy fresh cut watermelon having only what you need or buying a whole melon which is too much and wasting product?

loss of product=loss of moneyBuying only what you need is important, but is this option better in a quality standpoint? 

5

Materials and Methods•Seedless watermelon --- Citrullus lanatus

•Purchased from Publix Supermarket

•Fresh-cut samples cut on day zero

•Whole fruits cut on day of measurements

•Control whole fruit cut on day of measurements

6

For this experiment I used seedless watermelon (Citrullus lanatus) purchased from Publix Supermarket. The watermelons were bought as whole fruits and the fresh-cut samples were cut on day zero of the experiment. The whole fruit treatments were cut on the day of measurements.

6

Place fresh cut samples

in clear, closed plastic

containers

Material and Methods

7

Clean melons in soapy warm water

Dry melons Sterilize melons in

bleach Cut melons in

sterilized cooler

Place melons randomly on cart in

5 C cooler

Place melons randomly on cart in 15 C cooler

(CONTROL)

Data Taken

Day 1

Day 6

Day 12

When the watermelons arrived, they were first cleaned in soapy, warm water and dried. Since we were examining fresh‐cut, all materials needed to be sterilized in order to avoid bacteria growing on the fresh‐cut in the cooler. Safety is a major concern with fresh‐cut produce, but also, we did not want bacteria to be the reason for quality deterioration. We wanted to see how the storage effected the melons. After the melons were dried, they were sterilized in bleach and moved to a sterilized cooler. Here, 6 melons were cut and the middle flesh of each fruit was placed inside a corresponding plastic container to mimic how the product is sold in the market. The plastic container held 6 pieces of fruit and I tried to make each piece similar in height and length. The samples were placed randomly on a cart and left in the 5C cooler. I also had 6 whole watermelons in the 5C cooler to be cut on the day of measurements. For our control, 6 whole watermelons were placed on a cart in 15C. Data was taken on day 1, 6, and 12. 

7

Measurements•Pictures of each treatment

•Weight (grams)

8

Color Reading

CO2 + O2 FirmnessLiquid Content

When I was taking measurements, the first thing I did was take the CO2 and O2 in 2 plastic containers of the fresh‐cut fruit. Next I cut 2 whole watermelons from the 5C cooler and placed six pieces from each melon in a corresponding plastic container. Finally, I cut 2 whole watermelons from the 15C cooler and placed 6 pieces from each melon in a corresponding plastic container. I moved the samples to the lab, took pictures, the weight, color readings, liquid content of the fresh‐cut pieces from day 0, and firmness of each cut piece. 

8

Statistical Analysis•Completely Randomized Design

•6 samples per treatment

•2 replications

•Treatment 1: 5C cooler (WHOLE FRUIT)

•Treatment 2: 5C cooler (FRESH CUT)

•Treatment 3: 15C cooler (WHOLE FRUIT CONTROL)

I had a Completely Randomized Design with 6 samples per treatment and 2 replications.Treatment 1: 5C cooler (WHOLE FRUIT)Treatment 2: 5C cooler (FRESH CUT)Treatment 3: 15C cooler (WHOLE FRUIT CONTROL)Again, the fresh-cut watermelon was cut on day 0 of the experiment and the whole fruit in the 5C cooler and whole fruit in the 15C cooler were cut on the day of taking measurements. Each day of measurements, I looked at 2 melons from each treatment and 2 containers from the fresh-cut treatment.

9

Results

10Day 1 of measurements Day 6 of measurements Day 12 of measurements

This is a overview picture of each treatment for the 3 days of taking measurements. From top to bottom, the treatments are: control whole fruit stored at 15C, whole fruit stored at 5C, and fresh‐cut fruit stored at 5C. 

10

Results•Liquid Content

0

2

4

6

8

10/11/2018 10/16/2018 10/22/2018

F

Day 1Liquid

Content

Day 6 Liquid

Content

Day 12Liquid

Content

Average Liquid Content (mL) of fresh cut samples after storage in cooler

11

The major component of quality deterioration in watermelon is the loss of cellular integrity leading to loss of liquid from the fresh‐cut fruit. Day 12 had the highest liquid content lost, which is to be expected. The longer the fresh‐cut is stored in a cooler, the more it will deteriorate and lose water content.  However, there was not as much liquid present as expected. 

11

Results• Color

L*

a*

b*

C: Control placed in 15CF: Fresh cut at beginning of experimentW: Whole fruit cut day of measurements

0

10

20

30

40

C F W0

10

20

30

40

C F W0

10

20

30

40

C F W

Day 1 Color Reading Day 6 Color Reading Day 12 Color Reading

Next measurement analyzed was the color of the watermelon pieces. There was not a significant difference between the treatments and the readings were all very similar. Visually, the fresh‐cut stored for the 12 days did show some color variation from the whole fruit cut the day of the measurements. The whole cut had the nice pink vibrant color.  

12

Results• Firmness and Work of Cutting

Firmness (g)

Work of Cutting/Toughness (g*sec)

C: Control placed in 15CF: Fresh cut at beginning of experimentW: Whole fruit cut day of measurements

0

5000

10000

15000

20000

25000

30000

C F W0

5000

10000

15000

20000

25000

30000

C F W

0

5000

10000

15000

20000

25000

30000

C F W

Day 1 Firmness Day 6 Firmness Day 12 Firmness

Firmness is also a big factor with watermelon. There is a sweet spot where the consumer does not want too hard of a watermelon, but not too soft. They want a nice crisp and juicy piece to bite into. For each measurement, the whole cut melon stored at 15C had the lowest firmness. On day 1 the whole cut melon stored at 5C had the best firmness, but then went down for day 6 and 12. It is interesting that the fresh‐cut firmness was the best on day 6 and 12 measurements. When fruit begins to deteriorate the cellular integrity decreases and the fruit will become less firm, but I did not see this with my melons.  Visually, the fresh‐cut looked more mealy compared to the fruit cut the day of measurements but looking at the data, there was a different story. 

13

Results• CO2 + O2 inside plastic container

CO2% Concentration

O2% ConcentrationF: Fresh cut at beginning of experiment

0

5

10

15

20

25

10/11/2018 10/16/2018 10/22/2018

F

Average CO2 and O2 of fresh cut samples after storage in cooler

Day 1 Day 6 Day 12Day 12

Finally, the CO2 and O2 were measured inside the plastic container. There was no significant difference between the treatments and no trend in concentrations. Watermelon is a non‐climacteric fruit so respiration and CO2 should decrease over time (not increase to a peak and then decrease as seen in climacteric).

14

Results•Day 1 of Measurements

15

Here is the fruit after 1 day in storage. The texture looks pretty firm in each and color is a nice pink. 

15

Results•Day 6 of Measurments

16

Here is the fruit after 6 days in storage. The fresh‐cut watermelon cut on day 0 and stored for 6 days had lighter color and looked a little “dried out”. 

16

Results•Day 12 of measurements

17

Here is the fruit after 12 days in storage. The whole melons cut the day of measurements looked more firm compared to fresh‐cut. The fresh‐cut has begun to loose their color and look mealy. 

17

Conclusions•Overall, after 12 days the fresh cut:

oVisually color changed, texture was more mealy, increased liquid content

•Previous research shows increased fresh-cut lost liquid contentoLoss of cellular integrityoDid not see a major increase in released liquid contentoOne replication of fresh cut had 15 mL + another had 0.01 mL

•More research necessary to understand new cultivarsoSample size not large enough to draw conclusionsoPotentially stronger cultivars that can withstand longer storage periods of

fresh cut 18

Overall, after 12 days the fresh cut: visually color changed, texture was more mealy, and had

increased liquid content. Previous research shows that there is an increase in liquid lost by the fresh-cut watermelon,

18

due to loss of cellular integrity. However, I did not see a major increase in lost liquid content from the fresh-cut fruit. On day 1 of measurements, one of the plastic containers had 0.5 mL of liquid and the other had 9.5 mL of liquid. On day 6, one container had 0 mL and the other had 4.4 mL of liquid. Finally, on day 12, one container had 0.01 mL of liquid and the other had 15 mL. An increased number of samples would be necessary to understand the true deterioration of whole watermelon versus fresh-cut watermelon because in this experiment, there was too much variation between replications.

18

More research is also necessary to understand new cultivars produced in the market. New cultivars could have firmer flesh and stronger cellular integrity to help limit water loss. They could also potentially withstand longer storage/shelf life periods when fresh cut. Overall, the sample size was not large enough to draw major conclusions.

18

Questions?

Thank you for your time and have a great day!If there are any questions feel free to email me. 

19