The Effect of Time and Temperature on Storage of Fresh Pechay

I.Introduction

A. Objectives

The study is performed to discuss the effect of time and temperature on the storage of fresh pechay. It is also done to explain the difference of low and high temperature on the storage fresh pechay. Lastly, to explain other factors related to time and temperature that may affect the storage. Through conducting this study, the proper storage conditions of food items will be determined.

B. Significance of the Study

The study aims to show the effect of time and temperature in the storage of fresh pechay. This will determine whether the fresh pechay will react positively or negatively towards the conditions of its storage. This study will be using two set-ups which will be observed three times. One of the set-ups will be placed in a place with room temperature only, around 30º C. The other set-up will be placed inside the refrigerator, about 48º F.

The effectivity of the two different set-ups will be indicated by the resulting qualities of the pechay bunches. This will be helpful in determining the proper storage techniques that will maintain the physical and nutritional qualities of food items.

This experiment is done in the Bio-assay Laboratory, Institute of Human Nutrition and Food, College of Human Ecology, UPLB.

II.Review of Literature

Pechay, scientifically known as Brassica rapa chinensis, is considered as one of the popular vegetables here in the Philippines. It is characterized by its broad, green leaves wrapped in its succulent, whitish compact head. This is mostly used in Chinese dishes such as pancit and kimchi, since it is also known as the Chinese cabbage. The physical properties of pechay, like its leaves, may determine its appropriate function, cookery, and storage.

The leaves of pechay play an important role in this study, since they are greatly exposed to the effect of time and temperature during storage. A leaf is composed of stomata, a structure where the exchange in gas and water occurs. This appears as tiny holes which releases gas and water to the surrounding.

Transpiration is an essential process that is involved in this experiment. This is the process wherein plant structures, particularly their leaves, allow the release of water to the surrounding. This is done so that there would be an equal amount of moisture in and outside the plant. In the case of the pechay bunches, they release greater amount of water during the long storage time This affects the capability of the bunches to resist wilting and deterioration.

The concern of conducting this study is about the storage of the fresh pechay bunches. Storage largely influences the quality that a food will have after some period of time. It is an essential stage that most common food items because it helps prevent scarcity, enable the availabilty of seasonal food items almost throughout the year, and reduce losses from the surplus of harvests.

Ideally, foods must be stored in an optimum temperature far away where microorganisms can tribe. This will then depend on the type of microorganisms that may grow in a certain food item. In our case, we often use methods of low temperature storage such as refrigeration and freezing.

Temperature is one crucial factor to be considered during storage of the food items. It is because food items have different capability to withstand the effects of high and low temperature to them. Though application of elevated temperature may help plants to continue essential processes, they will also reach an optimum point wherein temperature can no longer affect them, thus they may have decrease in metabolic rate. In this case, adaptations of plants such as having thick skin, and hairs on leaf surface would be of great help.

Time is considered as an important factor whenever we store fruits, and other food items. It will determine the quality of a certain food after it has been stored. This factor goes along with the others such as temperature, place of storage, and the food item to be stored. Time must be properly managed and monitored, since it is crucial that every food item has only a specific time of storage.

Dry and basic foods are often stored for longer time, as implicated by their morphology. On the other hand, moist and acidic foods take short time of storage because they can be easily contaminated with bacteria, and other microorganisms.

As said, time and temperature are affected by other factors of storage such as postharvest handling of the food item, type of packaging to be used for storage, humidity in the storage area, and nature of the food item to be stored. If these other factors would be held properly and constantly, then it is only the time and temperature to be monitored strictly to achieve the desirable quality of the food item being stored.

Postharvest handling of food items is the way they are treated soon after harvest up to the time that they will reach our plates. This must be done carefully so that mechanical damage of food items will be avoided. It is because physical damages that might happen to food items would be conducive for deterioration to occur faster. If proper postharvest handling is done, then the food item is enhanced for preservation and storage.

Regarding the type of packaging to be used for storage, the components and effectivity of the material must be considered. This will greatly affect the temperature of the storage area. If a certain food item must be stored under room temperature, it would be wise to use packaging material which would not trap the moisture released during storage that may add to faster deterioration. The material should not be also conducive to wilting and contamination from outside factors. If a food item should be stored inside the refrigerator or in a place with low temperature, the packaging material to be used must be

Another factor in storage of food items is humidity, which is the amount of moisture contained in the atmosphere. Generally, the greater is the humidity, the greater also is the possibility of deterioration. It is because the water activity in a certain food will be further increased. This condition is more favorable for microbial activity, and eventually, faster spoilage.

The nature of the food item to be stored is also one of the essentials to be considered in this study. This will determine the tolerance and capability of a certain food item to accommodate or resist the effects of the other factors during storage. This may refer to the morphology of the food item,and iots classification being acidic, basic, or neutral. As mentioned, dry and basic food items can be stored longer than foods which are moist and acidic, as far as microorganisms' tolerance is concerned. Also, plants with specialized adaptations in their physical structures can be used for longer preservation as compared to common plants/food items.

III. Materials and Methods

Prepare the materials that will be needed in doing the experiment which are the two fresh pechay bunches, and thermometer. Place one bunch of pechay in a place with room temperature, record the initial temperature reading. Place the other bunch inside the refrigerator, particularly in the vegetable crisper. Record the temperature. Observe the bunches of pechay for three days (consecutively, or with intervals).

IV. Results and Discussion

A. Results

The following table and graph will show and interpret the results obtained from the experiment through measuring the weights of the pechay bunches for three times.

Table 1. Effect of temperature on storage of pechay. Temperature | Changes in Weight per day | Visual Quality |

1 | 2 | 3 | Total |

Wt (g) | % | Wt (g) | % | Wt (g) | % | Wt (g) | % |

Room | 43 | 0 | 41.5 | 3.5 | 20 | 51.8 | 20 | 51.8 | Dry, green, yellowing | Refrigerator | 21 | 0 | 19 | 9.5 | 15 | 15 | 15 | 21.1 | Dry, thin, yellow-green |
Number of days
Illustration 1.Effect of temperature on the storage of fresh pechay.

B. Discussion

The observations and measurements obtained showed that there is a decrease in weight of the fresh pechay bunches, relative to the length of the time of storage. Comparing the weight loss of the pechay inside the refrigerator and with the one in a room temperature, there is a faster rate of loss with the pechay bunch stored in a room temperature than inside the refrigerator.

In Table 1, the weights of the pechay inside

V. Summary and Conclusion

In the experiment, it is concluded that the longer the storage time, and the higher is the temperature of fresh pechay, the greater is the probability of its deterioration or spoilage. The effect of temperature depends on the tolerance of the fruit or vegetable. Generally, low temperature affects their texture, color, and flavor. It also lengthens their shelflife by reducing the water activity, thus preventing the presence of deteriorating microorganisms. The application of low temperature to the storage of fruits and vegetables also affect their texture, color, and flavor. On the other hand, it hastens metabolic processes. Because of this, fruits and vegetables may easily ripen, and eventually spoil or deteriorate since there would be a fast rate of metabolism favored by increase in temperature.

VI. Literature Cited

Bonner, J. & Galston, A. W. (1952). Principles of plant physiology. W. H. Freeman Company: San Francisco, California. Rey, P. M. (1972). The living plant (2nd ed.). Holt, Rinehart and Winston, Inc.: USA.