Page 29 - Simply Veg 3.21

to the respiration rate; if this can be slowed down the storage time can be increased. Also produce with a low respiration rate will generally store for a longer time. Root crops are a good example of a crop with a low respiration rate whereas leafy crops tend to be high. Apples and pears have a low rate, but strawberries are high.
It is important that any fruit or vegetables to be stored are of good quality and free from pest and disease attack and any other form of damage. Any crop that has been damaged by pest, disease or physical damage will rot in store and possible spread to healthy produce. Do not roughly handle the crops to avoid bruising or cuts. Any crops that are not of high quality should
be used during the autumn or soon after harvesting, some will keep for a couple of weeks possible a bit longer.
Vegetable fruits – these can be divided
into two main groups. The legumes like peas and beans and the cucurbits (cucumber and melon) and the Solanaceae fruits of tomato, pepper and aubergine. The second group can be damaged by low temperatures (chill damage) so should not be stored too cold. Peas and beans should be stored at 0°C while in the pods, but both of these crops are usually frozen soon after harvesting. If stored in the pods in a fridge they should stay fresh for 7 to 10 days. Runner and French beans are best stored at 3 to 5°C and will store for 5 to 7 days before becoming rather limp unless in a poly bag or wrapped in a damp tea towel. Cucumber, melon, pepper and aubergine
can be stored for 7 to 10 days in a fridge, possible longer depending on what stage they were harvested at. They will last 14 days
If possible do the harvesting early in the morning while the produce is still cool from overnight and keep them cool until they are in the store. Also always aim to reduce the temperature as quickly as possible after harvesting as this increases its storage life. Cool by cold water or air depending on the crop.
The next factor is the atmosphere and which gases and the amounts it contains as well as the humidity level. It is important to maintain a high relative humidity to minimise water losses from the produce especially crops like cabbage that will wilt and shrivel. Dry atmosphere will dehydrate the produce and reduce its quality and keeping time.
The main gases that affect produce in store are oxygen, carbon dioxide and ethylene. Ethylene is a hormone produced by ripening fruit like bananas, tomatoes, apples, pears, etc. and this basically speeds up the ripening process which will reduce the storage life
of the produce. Ethylene can have a slightly different effect on some other crops but in most produce increases the respiration rate. In commercial fruit stores they reduce the oxygen levels to very low and increase the carbon dioxide or nitrogen levels; this slows down the respiration rate and increases
the storage life. This is not feasible in a domestic situation but try to avoid frequent air changes which will allow in fresh oxygen and the CO2 out and this should help.
Root crops should be stored in areas of high relative humidity to minimise water loss. Many fruit and vegetables are 80% to 90% water so any loss will result in a deterioration of quality, weight reduction, shrinkage and possible wilting or shrivelling. Care should be taken in using water to cool produce
as it can spread disease, rots, decay and dirt which leads to losses in storage. Water loss from produce is by transpiration so this needs to be reduced by high humidity and cool temperatures. Transpiration can also be reduced by dipping the produce in a wax solution or wrapping in polythene, cling film or waxed paper. The relative humidity is the amount of water the air will hold at a certain
The conditions in which
the crops are stored will
vary depending on the crop
which I will cover later but
the important conditions
are temperature, humidity,
atmosphere and ripening.
Once a crop is harvested
many will start to deteriorate
unless they are stored quickly
and correctly. The speed of
deterioration depends on which crop it is and the conditions they are stored in.
The most important conditions in storage is temperature and as a whole the lower
the temperature the better within reason.
If it drops below freezing (0°C) this can
result in cell damage especially if the crop
is not usually subject to low temperatures like tomatoes, cucumbers and peppers. Lower temperatures reduce the respiration rate which reduces the rate of deterioration so keep most stored crops cool at around 0°C to 4°C. A reduction of just 1°C can increase storage life of some produce. This also tends to slow down any bacterial and fungal growth which could rot the produce. Lowering the temperature also slows down the production of ethylene (see below). To be sustainable make use of winter temperatures rather than fridges.
Temperature Recommendations
Leafy vegetables – such as lettuce, cabbage, salad leaves, Chinese cabbage etc. all have a high respiration rate and should be cooled to 1°C as soon as possible after harvest by dipping in icy water and then stored in the salad box in the fridge. They should stay fresh for 5 to 7 days.
if harvested when first mature and chilled straight away. Pumpkins and squash can be stored at 10 to 12°C for a number of weeks.
Root crops – this includes the bulbs like onions,
shallots and garlic as well as carrots, beetroot, parsnip and celeriac and the tubers including potatoes and sweet potatoes. They all have a low and should be stored as near
Any crop that has been damaged by pest, disease or physical damage will rot in store
respiration rate
to 0°C as possible at which they will store for 6 months. If the storage temperature rises
to 5°C or above the storage period reduces rapidly leading to rotting and sprouting. The exception to the low temperature is sweet potato which should be stored at 10 to 12°C as it is prone to chilling injury. Potatoes can be stored at 2 to 5°C if lower temperatures are not available.
Fruit – apples and pears if picked at the correct stage, not damaged, are the right cultivars and stored at 0°C will store for up to 6 months or more. Cool the fruit straight after picking. Berries are more perishable and most will only store for a few days
in a fridge at 0°C, so are best frozen or preserved by bottling.
Too many marrows!
Apple storing tray
Simply Vegetables 29