Food Sciences: Auto Gas Permeability Testing in Fruit and Vegetable Preservation

Food Sciences: Auto Gas Permeability Testing in Fruit and Vegetable Preservation - Abstract: This article briefs on the methods and mechanisms of preservation and storage for fruits and vegetables, and presents a detail introduction about how to obtain the accurate permeability data of preservative film under lower temperature storage environment.

People often focus their attentions on the guarantee period when buying food. Guarantee period is a term used for the safety of food. Food within this period can be eaten safely. However, with the improvement of living standard, people began to pay close attention to the freshness of food. Therefore, the concept of food preservation came into being. Food preservation, which has a higher requirement than quality guarantee, refers to that on the basis of safety insurance, the nutrition, color, texture and flavor can also be guaranteed.

Summary: Plastic wrap is one of the commonly used methods in fruits and vegetable preservation. And it is always used combining with low temperature storage. Therefore, obtain the permeability data of plastic wrap under low temperature is very important to the research of preservative mechanism and effect.

Author: Labthink Instruments Co.,Ltd.

Keywords: preservation of fruit and vegetable, low temperature, permeability, data fitting

Indonesia Supplies 10 percent of Singapore's Vegetables Demand

Coordinating Minister for Economy, Hatta Rajasa, said Indonesia has met 10 percent of the thousands of tons of Singapore needs on vegetables during 2010.

"In 2010, we've reached 10 percent of the needs of Singapore's supply of vegetables," Hatta said after accompanying President Susilo Bambang Yudhoyono on working visit in Riau Islands Province on Sunday.

Hatta emphasized that the government agreed to make the Riau Islands as a center of agriculture, especially vegetables that will be exported to Singapore.

The government hopes that the existence of the Riau Islands as a center of agriculture could boost vegetable exports Indonesia to Singapore.

"Until 2014, we already have to increase above 40 percent," he said.

Hatta said the president has commissioned a number of researchers from the Bogor Institute of Agriculture to examine the types of agricultural products are suitable to be developed in the Riau Islands and then exported to Singapore.

The President also asked local officials to plan special agricultural land clearing for agricultural products.

The President also reminded that all have to give priority to regional development while maintaining environmental sustainability.

Presidential visit also resulted in an agreement to build the Riau Islands to be integrated area for the various sectors, including fisheries, business and tourism.

For that, the government will build a number of infrastructure, especially ports and bridges. It will able to increase the connectivity among islands in Kepulauan Riau Province.

In fact, according to Hatta Rajasa, Ministry of Communications is ready to give one unit of the vessel to support the inter-island connectivity.

The government also has prepared a draft spatial Riau Islands are considered to facilitate the achievement of government targets to make the province as one of the attractions of Indonesia.

"The discussion of this spatial structure at the ministerial level has been completed, and just remained to discuss with the House," said Hatta Rajasa.

In the energy sector, the government will make the Natuna as a supplier of energy, particularly gas, to the Riau Islands itself and several other areas.

Source: Antara News

A Guide for Canning Vegetables

A Canned vegetables

As all we known that all agricultural products is perishable. This perishable characteristic is all because of a high water content level consisting in them. This condition happened to vegetables as one of agricultural products that need time to reach to the consumers. 

Therefore, it's need a technique to preserve vegetables to not defect when it's ready to be consump by the consumers. One of the preservation techniques that reliable for vegetables is canning.

All vegetables, except tomatoes, require processing in a pressure canner with a weighted control or dial gauge. Because tomatoes are more acidic, they can be safely processed in a boiling water bath.

Food Safety Concerns

A deadly form of food poisoning, botulism, can occur when low-acid foods are improperly processed. The higher temperatures of the pressure canner are necessary to ensure that any Clostridium botulinum spores are killed. If the organism is present in canned low-acid vegetables, botulism toxin can be produced. Even sealed containers without any visible sign of spoilage can contain botulism toxin.

• To avoid the risk of botulism, make sure your pressure canner is in good working order; check the gauge yearly for accuracy; follow all canning recommendations exactly.
• Since the rate of heat penetration and acidity is affected by the combination of foods used, do not can vegetable mixtures such as vegetable soup or chili sauce unless you have a laboratory tested recipe.
• Never thicken vegetables prior to canning. For mixed vegetables look up the processing time for each vegetable in the mixture. Use the processing time for the vegetable that requires the longest processing time.
• Always check home canned vegetables carefully for signs of spoilage before and after opening. When opening, watch for spurting liquid, an off odor, or mold.

If there is any doubt in your mind whether home canned food food is spoiled, don’t use it. Burn any spoiled food or dispose of it so that it will not be eaten by humans or animals. Also, be sure to boil low-acid vegetables for 10 minutes before tasting or serving.

Select and prepare vegetables carefully

• Choose only fresh, young, tender vegetables. Wash thoroughly, small amounts at a time, under running water or through several changes of water. Lift the vegetables gently out of the water so dirt washed off will not settle back on the food. Rinse the pan or sink between washings.
• The number of quarts of canned food from a given amount of fresh vegetables depends on quality, condition, maturity, and variety of the vegetable; the size of pieces packed; and the way the vegetable is packed-raw or hot pack.
• Generally, the following amounts of fresh vegetables (as purchased or picked) make 1 quart when canned:
• Asparagus: 2 to 4 pounds
• Beans, lima, in pods: 3 to 5 pounds
• Beans, snap or green: 1 to 3 pounds
• Beets, without tops: 2 to 3 pounds
• Carrots, without tops: 2 to 3 pounds
• Corn, sweet, in husks: 3 to 6 pounds
• Peas, green, in pods: 3 to 6 pounds 
• Pumpkin or winter squash: 1 to 3 pounds
• Spinach and other greens: 2 to 6 pounds 

Use standard jars and lids

• Use only jars and two-piece lids made especially for canning. Check jars and lids for cracks, chips, dents and rust; these defects cause sealing failures. Commercial jars such as those for mayonnaise are not recommended for home canning because they are not designed for use with two-piece lids and because the glass is more likely to break during processing. Wash jars in hot, soapy water; rinse well. Prepare lids and bands according to manufacturer’s directions.
• Mineral deposits or hard water film on jars can be removed by soaking the empty jars for several hours in a solution of 1 cup vinegar per gallon of water. To avoid mineral deposits on jars during processing add 1⁄4 cup vinegar per gallon of water used in the pressure canner.

Fill jars and adjust lids

• Vegetables can be packed raw, or preheated and packed hot. See Table 1 (released in next posting) for specific directions.
• Most raw vegetables should be packed closely because they shrink during processing. Corn, lima beans and peas absorb liquid and expand when processed so should be loosely packed. To ensure proper heat penetration, do not pack vegetables too tightly. Vegetables packed hot should be at or near boiling temperature and should be packed loosely.
• Use the hot cooking liquid and add boiling water, if needed, to fill the jar and cover the food for both raw and hot packed vegetables. If the vegetables at the top of the jar are not covered they may darken.
• Salt is not needed for preservation in canned products but can be added for flavor. Use 1 teaspoon per quart or 1⁄2 teaspoon per pint.
• The space between the packed food and liquid and the top of jar is called headspace. The amount of headspace required is given with details for canning each vegetable. Too much or too little headspace will affect jar seals.
• Slide a non-metallic spatula between food and side of jar to remove any air bubbles. Wipe jar rims to remove food particles that might interfere with sealing. Adjust lids.

Check altitude

• As altitude increases, water boils at a lower temperature (below 212° F). Lower temperatures are not as effective for destroying organisms. Therefore, when using a pressure canner, the pressure must be increased as altitude increases.

Process in a pressure canner

• Partially fill canner with 2 to 3 inches of water. Place jar rack and sealed jars in canner. Fasten lid. Heat on high. After steam exhausts for 10 minutes, add weighted gauge or close petcock. Allow canner to reach designated pressure. Start timing when designated pressure is reached. Regulate heat to maintain a constant pressure.
• Process for the time recommended in Table 2 (released in next posting). Do not reduce the processing time.
• When processing is complete, remove canner from the burner.
• Allow the canner to cool at room temperature until it is fully depressurized.
• This will take 30 to 60 minutes depending on the type of canner. Do not rush the cooling by setting the canner in water or by running cold water over the canner.
• Do not open the vent or lift the weight to quicken the reduction of pressure.
• When the pressure has dropped to zero, carefully open the petcock or remove the weighted gauge. Wait 2 minutes, then slowly release and remove the canner lid.

Remove and store jars

• Take jars from canner and set upright on a rack or folded cloth away from drafts. Do not tighten the screw bands.
• Allow jars to cool undisturbed for 12 to 24 hours, then check for sealing failures. 
• To test jar, press center of lid. If lid is down and will not move, jar is sealed. Remove screw bands carefully. 
• Wash, dry, label, and store jars in a cool, dark place. If any jars have not sealed, place in refrigerator and use within two days. Vegetables can be reprocessed with fresh liquid, new lids and clean jars, and the full processing time, but quality will be affected.

Source: 

• Textbook of Food Science and Technology

Next Post: Guidance for Preparing and Packing Vegetables

Non Food Applications of Palm Oil and Palm Kernel Oil (3)

Palm Based Biodiesel 

A better alternative for the environment because it is made from renewable resources and has lower emissions compared to petroleum diesel.

Made through a chemical process called transesterification whereby glycerin is separated from the fat or vegetable oil. Transesterificaton chemically break the molecule into two products which is Methyl Ester (the chemical name for biodiesel) and glycerin (a valuable byproduct usually sold to be used in soaps and other products).

Palm-based methyl esters have been extensively tested as a substitute for diesel in taxis, buses, lorries, tractors and stationary engines. The data available to date indicate that cold starting is easy and engines run smoothly with less smoke and reduced content of carbon particles in the exhaust fumes. The use of palm methyl esters as a diesel substitute contrast with the use of crude palm oil which does not require any modification of the engines. The economic viability of palm methyl ester as a diesel substitute will depend on the costs of diesel, crude palm oil and glycerin.

Alpha-Sulphonated Methyl Esters

Alpha-sulphonated methyl esters (SME) are a new class of anionic surfactant. Recently SME have received a lot of attention as active ingredients inwashing and cleaning products for a variety of reasons which include:

• Good lime-soap dispersing characteristic
• Good detergency especially in hard water and in the absence of phosphates
• C14, C16 and C18 methyl esters have best detergency
• Good biodegradability

Distilled fatty acid methyl esters with a low iodine value are used as the starting material for the production of SME. The fatty acid methyl esters are first reacted with sulfur trioxide at 80C ĄV 90C in a falling film reactor. The dark product obtained is bleached using hydrogen peroxide and then neutralized with alkali to produce the alpha-sulphonated methyl esters. Because of the good detergy of C16 ĄV C18 fatty acid methyl esters, palm stearin provides a suitable and cheap source of raw material for the production of SME. The detergency properties of SME derived from palm stearins have been found comparable with those of linear alkyl benzene sulphonates (LAS), the workhorse of the detergent industry. In hard water, the performance of SME is superior to that of LAS in phosphate-free detergent formulations.

Soaps and Fatty Ester for Soap

Soaps

Soaps are mixtures of sodium salts of fatty acids which can be derived from oils or fats by reacting them with caustic soda at 80 oC -100 oC in the process known as saponification. The use of soap as laundering agent and for cleansing the skin is many centuries old. Although modern detergents have almost eliminated the use of soap for home laundry purposes soap is still the main ingredients in toilet bars for personal use. The incorporation of both C16-C18 and C12-C14 fatty acids in soaps is important as they provide the cleaning, solubility and foaming properties required. Tallow and coconut oil, respectively have been the traditional sources of these fatty acids. A comparison between the fatty acid compositions of palm oil, palm stearin, tallow, palm kernel olein and coconut oils are rich in C12-C14 fatty acids.

Palm stearin and palm kernel olein are produced along with palm olein and palm kernel stearin when palm oil and palm kernel oil are fractionated. While palm olein and palm kernel stearin have higher added value because of their specific food applications. Palm stearin and palm kernel olein are normally sold at discount prices. Several studies carried out by Kifli et al revealed that palm stearin and tallow can be formulated together with palm kernel oil to give soaps that are comparable with tallow palm kernel olein blends. Since Palm stearin is cheaper than tallow the resulting soaps are expected to be cheaper. Perfume retention of palm based soaps has also been found to be better than that of soaps made from tallow. More interesting are the observations of Kifli et al on palm stearin and palm kernel oil blend that soaps based on these were found to have better foaming power and colour. Poor colour and discolouration are common complaints expressed by soap manufacturers attempting to use palm kernel oil for production of white soaps.

Fatty Ester for Soap

Fatty esters are increasingly being used for the production of soap. Soaps produced from fatty esters are normally better in quality than those made from fatty acids since the fatty esters can be better purified. When soap is made from fatty acids, esters and alcohol will be produced and its complete removal is necessary before the soap can be certified fit for use.

Fatty Acids for Candles

In the manufacture of candles from fatty acids a ratio of about 7:2 is required between the C16-C18 in order to ensure maximum shrinkage and hence easy removal from the mould. The ratio favours the used of fatty acids from palm kernel oil since they have a high palmitic acid content. Candles derived from palm fatty acids have longer burning life, produce less smoke and drip less tha candles made from petroleum wax but uncompetitive pricing has so far prevented the commercialization of palm-based candles.

Fatty Acids for Cosmetic Products

Only good grades of fatty acids can be used to make cosmetic products. The fatty acids normally used are myristic, palmitic and stearic. They serve various purposes i.e acting as lather improvers and conditioners, and providing luster and sheen.

Fatty Acids for the Production of Metallic Soaps

Another important application of palm fatty acids is for the production of metallic or non-sodium soaps. The most common ones are calcium and zinc palmitates and stearates. They can be prepared by either a fusion or a precipitation method. The process ability of rubber is improved by any fatty acids but zinc soaps have been found to provide better internal lubrication. The potential of palm-based calcium soaps as animal feed is being investigated.

Epoxidized Palm Oil, Polyols, Polyurethanes and Polyacrylates

Epoxidized palm oil can be produced by reacting palm oil, palm stearin or palm olein with peracids. Epoxidized oils especially epoxidized soyabean oil are used extensively as plasticizer for plastics particularly polyvinylchloride (PVC). A plasticizer increases the workability of plastic while stabilizer reduces the rate of degradation of a plastic by heat, light or micro-organisms. Epoxidized oils can fulfill both functions and their compatability with a plastic increases with their epoxide content. Because palm oil and its products have lower iodine value than soyabean oil. The epoxide contents of epoxidized palm oil are lower than that of epoxidized soyabean oil. As plasticizer or stabilizer, epoxidized palm oil are therefore not expected to perform better than epoxidized soyabean oil but their performance could be made comparable by slight modifications of the formulations. PVC jungle and rain boots plasticized or stabilized with epoxidized palm oil have been produced which are comparable in performance to those plasticized and stabilized with epoxidized soyabean oil.

The value of epoxidized oils lies in the versatility of epaxide rings. Being labile they can easily converted to other useful functional groups, thus diversifying end uses. Epoxidized palm oil can be converted to various polyols by reacting them with short chain polyhydric alcohols in the presence of catalysts. By changing the ratio of epoxidized palm oil to polyhydric alcohols, polyols with a range of hydroxyl values and viscocities can be produced. Polyols when reacted with isocyanates produce polyurethane foams. The water foam in the reaction acts as an internal blowing agents, thus avoiding the need to use environmentally unfriendly blowing agents such chlorofluorocarbons.

Polyols from epoxidized palm oil react with isocynates at a slower rate than do polyols based on petrochemicals. The resulting foams however have regular cell structures and exhibit good hydrophobicity. With suitable formulations these properties could be fully exploited to give rise to interesting products.

Polyacrylate resins can be produced from epoxidized palm oil by reacting them with acrylic acids. These resins can be applied on solid surfaces and when they are cured by UV-radiation, clear glossy finishes resulted. The hardness and tackiness can be increased or reduced by varying the amout and types of crosslinkers and the strength of irradiation used.

Retrieved from : 

• American Palm Oil

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