Spoilage of Fruits and Vegetable

Fruits and Vegetable

Contamination

When fruit and vegetable are called in the basket , containers or trucks during harvesting . they are subjected to contamination with the microorganism . Mechanical damage caused during transportation increase susceptibility to contamination and microbial invasion .Washing by agitation distribute spoilage organism from damaged part to whole fruit or vegetable / Trimming away spoiled part removes spoilage organism but if it is not done properly contamination of fruits and vegetables may also occur from processing equipment

Preservation

Asepsis

Fruits and vegetable may be subjected to contamination between harvesting and processing from container and from spoiled vegetable or fruit. Therefore ,care should be taken to avoid such contamination as much as possible . Basket and container should be free from microorganism and need cleaning and sterilization before use

Removal of microorganism

Microorgamismanddirt on the surface of vegetable and fruit can be removed by washing with clear water . If the water used for washing is not sterile , it may add spoilage organism . Therefor use of chlorine water detergent solution is better for washing . Trimming away spoiled part also remove spoilage organism . Clean fruit ,Juice can be sterilized by filtration.

use of heat

Vegetable to be dried or frozen or canned are branched . Blanching inactivates food enzyme and reduces and reduce the number of spoilage organisms fruit are seldom blanched before other processing because excessive physical damage . During canning heating at 100c is sufficient for fruits and heat can be applied by flowing steam or boiling water

Use of low temperatures

• Chilling:Vegetable are chilled by cold water ,ice or mechanical refrigeration or by vacuum cooling . It many cause precooling are done by cold water before normal cold storage. This process is called hydro cooling. The refreshing of leafy vegetable by a spray of cold water also held in preservation . Various chemical such as hypochlorite , propionates , sulfites is employed before or during chilling of fruits .Controlledatmosphere with increased carbon dioxide and oxygen concentration held in preservation selection of appropriate chilling temperature are necessary because the quality of some fruits and vegetable is damaged by cooling .
• Freezing :Vegetable and fruits are also preserved by freezing .Pretreatment such as washing sorting , trimming away spoiled part necessary before freezing .
• Preservation by drying : Many vegetables is dried by explosive puffing . In this process, pieces of partially dehydrated vegetable are placed in the closed rotating chamber . Heat is applied and chamber is pressurized to creation level and then the pressure is released instantaneously. This result in addition loss of moisture and formation of pores that further dried the product . Many vegetable and fruits are dried by solar drying
• Use of preservatives :Addition of preservative to vegetable is not so commons . Turnips are some times paraffined to increased their keeping time . Phenyl vapors control fusion potato znco3 eliminates the growth of mold in vegetables . some preservatives such as waxes ,hypochlorite ,biphenyl etc are applied on outer surface chemical including iodine ,sulfate biphenyl etc . Sulfur dioxide and sodium benzoate are added directly to fruit and fruit product . Gaseous preservation such as carbon dioxide and ozone are used in storage atmosphere of fruit .

Spoilage

Deterioration of flesh vegetable and fruits may result from mechanical damage ,action of food enzyme , microbial action or by combination of this factor . Mechanical damage caused by insect , bird , animal etc . increase susceptibility to deterioration by theri enzyme and microbial spoilage .Most commonly occring microbial spoilage of fresh vegetable and fruits are:

• Bacterial soft rot :Caused by Erwinia carotovora and related pectin fermenting bacteria . Rot appears water soaked , soft pften with bad odour.
• Gray mold rot : It is caused by Botrytis species . This sopilage is enchanged by high humidity and warm tempertur.
• Rhopus soft rot : Caused by species of Rhizopus eg. rhizopus . Rot is often soft and watwry the cottony growth of the mold with small black dots of sporangia cover the food.
• Alterriae rot : Caused by Alternaria tenuis and other species . Spoiled area becomes geenish brown early in growth of mold and later turned in to brown or black dots.
• Anthrecnose : Caused by Collectotrictum lindemuthioum and other species . It is characteristied by spotting of leaves and fruits.
• Blue mold rot :Caused by Penicillum digitatum and other species .Blue colour of rot is dut tobblue colour of spores .
• watery soft rot : It is manly caused by Sclerotinia Scterotiorum . It is found mainly in vegetables.
• Blck mold rot : Caused by Aspergillus niger . Rot appers black to black spores of the mold .
• Blck rot: It is maianly caused by Alternaria and sometimes by Ceratostomella ,Physalospora and other
• Pink mold rot :Cause by Trichothecium roseum
• Fusarium rot : It is includes varity of root , it caused by Fusarium .
• Greenytic mold rot :It isusually caused by Cladosporium and somerimea by green coloured mold such as Trichoderma.
• Brown rot :Casued by Monilinia Fructicold.
• Strem end rot :Caused by several genera of the mold such as Diplodia. Phomopsis, Alternaria and Fusarium species
• Sliminiess or souring : Caused by saprophtic bacteri in piled , wet and heating vegetables.

Spoilage of vegetable and fruit juice

Acidity of fruit juice range from 2.4-4.2 depending on fruit juice , suger concentration vary from 2-17 %. Although mold can grow on surface of fruit juice . High moistur concerned also favours yeast ans some bacteria . Deficiency of vitamin B discovrage growth of some bacteria common type of spoilage of fruit juice are ;

• Alcoholic fermentation by yeast .
• Lactic acid fermentaion by heterofermentativelactic acid bacteria
• Fermentation of organic acid of ice eg, fermentation of malic acid into lactic acid and succinic acid
• Slime production by leuconostoc species .

pH of vegetable juice is less acidic (5-5.8) and also contai plentiful supply of growth factors. Therefore , vegetable juice supports growth of fastidious lactic acid bacteriaCommon spoilage of vegetable juice acid fermentation , smile production etc. Vegetable juice contais sugar are less acidic tahn fruits juices having pH value in the range of 5-5.8 for the most of the part . Vegetable juices contain plentiful supplied of accessory facter for microorganism and hence supportthe growth of fastidious organism including lacti acid bacteria . Acid fermentation of raw juice by lactic acid bacteria may causse spoilage juice

Reference

Frazier, WC and Westhoff DC.Food Microbiology.3rd. New Delhi: Tata McGraw-Hill Publishing Company Limited, 1986.

Jay, MJ.Moderen Food Microbiology.Ed. India. 3rd. Delhi: CBS Publications and Distributions, 1987.