Task+2+Shelflife

= Home page = we met up on Monday to discuss for what can we do in this week. we decided that we need to prepare all samples on Tuesday, and research some information about shelf-life (John and Jie are responsibility) and packaging(Monica and Witthawatt are responsibility). i have researched something about the shelf-life of all ingredients, and the shelf-life of the brown rice tea that can be compared with our sample's shelf-life. moreover, our group done the sensory panel today, used 8 flasks to control the temperature with the same number of the assessors, but three of them are not good, so we think we need to order other three flasks for next sensory test. all the results are kept, and it will be calculated by the R project tmrw. we are decided that we will researched some information about the tasks 2-3 at night, in order to discuss them tmrw when we done the analysis of the results.

__RELEVANT LITERATURE__




( more important information of shelf-life by Jie) **Experiment Design** Direct effecting factors: Possible effecting factors: all literature researches are shown in our report.
 * __Humidity__: in generally, humidity control means control the water activity, it used one machine to check out which provided from tech. laboratory in University of Leeds.
 * 1) Checking the water activity of each unopened raw ingredients with each opened raw ingredients to compare the changes of the humidity effective.
 * 2) One week for estimation time to check the humidity changes by daily when all raw ingredients are stored in the stored room.
 * __Temperature__: used the thermometer to measure the temperature of the stored room during one week to check the changes of the temperature.
 * __Atmosphere__: stored one final sample in vacuum condition in can, stored another sample in normal air condition, and checked it after one week.
 * __Residual oxygen contained in tea bag__: stored our final product in the plastic bag, and used injector to add oxygen in, stored one week; the competitive sample are stored in vacuum condition one week, and compared them.
 * __Aerobic and anaerobic conditions__: are quite same as the first possible effecting factor, so the experiment is same as above one.
 * __Changes in the acidity__: check the pH of the product during one week.

__Researched by ** John **__

[|shelf life of green tea]

[|possible causes of bitterness of tea] > > ==Time== > > ==Light== > > ==Air and Moisture== >> Moisture is another enemy of loose-leaf tea because it leads to mold and ruins the tea's flavor and quality. Air contains moisture so, if you live in a humid climate, put a desiccant in the container to absorb moisture. Freezing and refrigeration expose your tea to moisture and can ruin the flavor. > > ==Warmth==
 * Loose-leaf teas are gaining in popularity as consumers learn about their benefits, such as high quality, fresh taste, better health and greater variety. A proper tea container is a must when you're storing loose-leaf tea to ensure maximum freshness. Tea leaves are delicate, so you must protect them from air, light and moisture as much as possible. Choose a jar or tin with a tight-fitting lid and don't use clear containers, which expose the tea leaves to light. Store different types of tea in separate containers to prevent changing the flavors and keep them away from other strong odors.
 * Loose-leaf teas are gaining in popularity as consumers learn about their benefits, such as high quality, fresh taste, better health and greater variety. A proper tea container is a must when you're storing loose-leaf tea to ensure maximum freshness. Tea leaves are delicate, so you must protect them from air, light and moisture as much as possible. Choose a jar or tin with a tight-fitting lid and don't use clear containers, which expose the tea leaves to light. Store different types of tea in separate containers to prevent changing the flavors and keep them away from other strong odors.
 * Loose-leaf teas are gaining in popularity as consumers learn about their benefits, such as high quality, fresh taste, better health and greater variety. A proper tea container is a must when you're storing loose-leaf tea to ensure maximum freshness. Tea leaves are delicate, so you must protect them from air, light and moisture as much as possible. Choose a jar or tin with a tight-fitting lid and don't use clear containers, which expose the tea leaves to light. Store different types of tea in separate containers to prevent changing the flavors and keep them away from other strong odors.
 * The shelf life of loose-leaf tea depends on its type. For instance, black tea has a longer shelf life than green tea. Tea rarely spoils, but the flavor decreases as time passes. Properly stored tea can stay fresh for up to 2 years. Some delicate varieties, however, have a recommended shelf life of just six to eight months.
 * Sunlight and indoor lighting both put off UV rays. As time passes, the UV waves break down the molecules in your tea, bleaching away both color and flavor.
 * Exposure to air can let odors from food, pollution and smoke get in your tea, so keep it in an airtight container. Some air will get in when you open the container but, if the container stays sealed most of the time, you can keep exposure to a minimum.
 * Heat also reduces the shelf life of loose-leaf tea by diminishing its flavor. Store your tea in an opaque container away from the oven, dishwasher and windows.

Whose responsibility?
The responsibility of determining the shelf life of a food, and thus its best-before or use-by date, lies with the manufacturer/packer. The most direct way of doing this is to conduct properly constructed storage trials under realistic, defined conditions. This may not be possible for smaller manufacturers, in particular those just entering the market. They frequently are looking for some rapid method to measure and estimate shelf life to allow them to put their product on the market as quickly as possible. Established manufacturers also are reluctant to rely solely on conventional storage trials to determine shelf life. Commercial pressures usually mean that a product must be marketed as quickly as possible after its development. Retailers may also have their own demands about shelf life of particular product categories especially those with a relatively short shelf life. Indirect methods of shelf life determination are frequently used to yield results which otherwise would be time consuming to obtain. These may involve so-called accelerated shelf life tests usually based on storage of the product at higher than normal temperatures or computer-based models. While these methods may prove useful, they must be applied with care. Storage of foods at higher than normal temperatures can induce changes in the food which would not occur at normal ambient temperatures. Also the rate at which normal changes are accelerated by higher temperatures must be known with acceptable accuracy. Models are useful only if they have been shown to mimic spoilage rates in like foods and not merely been developed under laboratory conditions. These models are not designed to be used beyond the range of data used to construct them.

Challenge studies
Challenge testing is a laboratory investigation to determine what can happen to a food product during processing and storage following inoculation with one or more appropriate microorganisms.

Domestic storage conditions and instructions
[|packaging of oolong tea] = Home page =