How the lemon get contamibated or spoiled by microorganisms

1. SPOILAGE AND
CONTAMINATION OF
LEMON

2. Food spoilageis the process where a food product becomes unsuitable to ingest by the
consumer. The cause of such a process is due to many outside factors as a side-effect of the
type of product it is, as well as how the product is packaged and stored. Due to food spoilage ,
one-third of the world's food produced for the consumption of humans is lost every year.
Bacteria and various fungi are the cause of spoilage and can create serious consequences for
the consumers, but there are preventive measures that can be taken.
Spoilage may arise from insect damage, physical damage, indigenous enzyme activity in the
animal or plant tissue or by microbial infections. Most natural foods have a limited life.

3. Most natural foods have a limited life. Perishable foods such as fish, meat and bread have a
short life span. Other food can be kept for a considerably longer time but decomposes
eventually. Enzymes can bring about destruction of polymers in some foods while chemical
reactions such as oxidation and rancidity decompose others but the main single cause of food
spoilage is invasion by microorganisms such as moulds, yeast and bacteria. In case of mould
spoilage a furry growth covers the food and it becomes soft and often smells bad. Bacterial
contamination is more dangerous because very often food does not look bad even though
severely infected, it may appear quite normal. The presence of highly dangerous toxins and
bacterial spores is often not detected until after an outbreak of food poisoning, laboratory
examination uncovers the infecting agent.

4. Spoilage organisms:
Yeasts: target fruits and vegetables due to their low pH .
Moulds: can grow even at very low water activity.
Bacteria: most bacteria have limited pH, prolytic bacteria can grow even in media with high pH
Favourable conditions for Spoilage
• high oxidation-reduction potential.
• lack of reduced conditions permits aerobes and facultative anaerobes to contribute to the
decomposition processes Spoilage initiated by molds.

5. Risk factors effecting
the lemonfor spoilage
Temperature
Humidity/Moisture
Ventilation
Biotic activity
Gases
Optimumcarryingtemperature: 10°C to 11°C (yellow lemons)
12°C to 14°C (green lemons)
Highest freezingpoint: -1 , 4°C
Acceptableproduct temp. to loadingintocontainer :Max. 5°C above
Optimumhumidity: 90%
Ventilation setting for containers : 25 m³/hr
Storagelife 2-3 months
Ethylene production Very Low
Ethylene sensitivity Moderate
Modified / controlledatmosphere 0%-10% CO2; 5%-10% O2
Potential benefits Low O2 delays senescence.
Elevated CO2 may delay loss of green colour

6. Spoilage in Citrus Fruits and Juices
Food spoilage problems occur with minimally processed, concentrated frozen citrus products.
Major spoilage can be caused by Lactobacillus & Leuconostoc spp . which produce diacetyl-
butter flavours.
Saccharomyces and Candida can also spoil juices.
 Lime juice contains ascorbic acid and citric acid which are naturally antibacterial and
antioxidants .
Increase In Water Activity (aw) Concentrated juicehas a decreased water activity (aw-0.8 to
0.83), and when kept frozen at about -10°C, juices can be stored for long periods. Also,
microorganisms in the frozen concentrated juices can begin the spoilage process after
addition of water. Ready-to-serve (RTS) juices present other problems as aw values are
sufficiently high to allow microbial growth.

7. Fruits and fruit products
The degree of specificity shown by many species of moulds , active in the spoilage of harvested
fruits in the market place or the domestic fruit bowl , reflects their possible role as pathogens
or endophytes of the plant before harvest .
Stages in spoilage of fruits:
• Usually fruits inhibit the growth of microbes until after harvest .
• Ripening weakens cell walls and decreases the amount of antifungal chemicals .
• Physical damage during harvesting breaks outer protective layers.
• Fruits have a low pH that inhibits most bacteria, except acid tolerant bacteria (Gram
positive lactobacilli & leuconostocs).
• Molds are tolerant of acidic conditions and are involved in the spoilage of citrus fruits .

8. Stages : spoilage and contaminationof lemon
Blue mold rot or storage rot is the most feared storage disease of citrus fruits and is caused by
two species of mold: green mold (Penicillium digitatum), which is of an olive-green color, and
blue mold (Penicillium italicum), which is of a blue-green color. Lemons are primarily attacked
by green mold. The fungal spores mainly penetrate through small injuries and initially form
white, circular spots of fungal growth, which are subsequently covered from the center outwards
with a green or blue-green sporulating layer. The peel becomes spongy, the pulp soft – a typical
instance of wet rot. Development is optimal at 20 – 27°C; growth still flourishes at 10°C and
comes to a standstill only at 4°C.
Blue mold is transferred from fruit to fruit by contact.

9. Day 3 Day 4 Day 8 Day 11Day 1 Day 6
Seawater, rain and condensation water promote green and blue mold growth.
Black rot (beginning at flower end) and stem-end rot (beginning at stem-end) are forms
of dry rot which may occur as early as during harvest. Moisture promotes blue mold rot
and black rot.

10. Alternaria Rot or black rot Caused by Alternaria tenuis.
Areas become greenish brown early in the growth of the mold and later turn to brown or
black spots.
Alternaria rot, caused by Alternaria tenuis and other species. Areas become greenish-brown
early in the growth of the molds and later turn to brown or black spots.
Prevention
• Removal of ethylene from storage room can reduce senescence and incidence of fungal
decay . It is generally recognised that proper storage of lemons improve quality ,i.e., juice
content , flavour , and color.

11. • Reduced temperature and increased carbon dioxide concentration also useful in
controlling mould spoilage during storage and transport but many fruits are
themselves sensitive to low temperatures and enhanced CO2 levels.
• Canned fruits are normally useful in controlling mould spoilage during storage and
transport.
• Mouldy fruit during storage and transport should be removed and destroyed.
• Good hyginene of containers and packaging equipment is essential to prevent a build-
up of mould propagules.
• Some biocides was used to prevent mould spoilage. - Benomyl has proved useful where
it can be applied to the surface of fruits , such as citrus , in which the skins would
normally be discarded.

12. Bio activity
Lemons display biotic activity.
• they are living organs in which respiration processes predominate, because their supply of
new nutrients has been cut off by separation from the parent plant.
• Inadequate ventilation may result in fermentation and rotting of the cargo as a result of
increased CO2 levels and inadequate supply of atmospheric oxygen (see Ventilation).
Note
Lemons do not cause contamination
Lemons are sensitive to contamination by dust, dirt, fats and oils. The holds or containers
must accordingly be clean and in a thoroughly hygienic condition .
Lemon is the best natural ingredient to preserve the food .

13. Swapna priya . M
19MSMB107
2nd Sem MSc