the bush for more than a week after ripening without 

 spoiling. This fact has allowed the grower to guarantee 

 price, quantity, and delivery date to produce buyers up 

 to one week in advance, something which has been 

 difficult to do with raspberries and strawberries. 



Raspberries and strawberries ripen quickly, so 

 harvesting the same planting frequently (once every 

 two days) is critical. Fruit harvested before it is fully 

 ripe will have a much longer shelf life than fully ripe or 

 overripe fruit. The optimum stage of maturity for the 

 raspberry occurs when the berry first becomes com- 

 pletely red, but before any darker hues develop. Straw- 

 berries with a white tip will retain their firmness much 

 longer than those harvested fully ripe, and will lose less 

 water during storage. Some training may be required 

 to teach pickers the proper stage and appearance for 

 harvesting. 



Fruit quality for fresh market raspberries usually 

 declines as the season progresses. Be sure the market- 

 ing channels are open before the first berries ripen, as 

 these likely will have the highest quality and largest 

 size for the season. 



Avoid touching a berry before it is ready for har- 

 vest. Place only undamaged berries with good appear- 

 ance in the pack. Studies have found that the magni- 

 tude of injury caused by human pickers can be so great 

 as to mask any other causes of deterioration. 



Overripe berries are susceptible to mold. Once the 

 mold growing on overripe berries sporulates, large 

 amounts of inoculum will be present to infect other 

 ripening fruit. Overripe berries also attract ants, 

 wasps, and other pests. Do not dispose of rotten berries 

 near the field, and pick them off the bushes. It may be 

 more economical in the long run to pay pickers for 

 harvesting rotten as well as marketable fruit. One 

 could pay an hourly wage to a worker for harvesting 

 only rotten berries so the other pickers will not con- 

 taminate their marketable berries with fungal spores. 



Harvest directly into small con- 

 tainers. Use half-pints for raspberries 

 and blackberries, and pints for the 

 other small fruit crops. Wide, shallow 

 containers are better than deep con- 

 tainers. Check with the buyer to deter- 

 mine what type of container is prefer- 

 able; each type has advantages and 

 disadvantages. The pulp containers 

 are inexpensive but stain easily. 

 Wooden containers also stain and are 

 expensive. Solid, clear plastic (polysty- 

 rene) containers will not stain and will 

 significantly reduce moisture loss 

 when used with a cap. In these con- 

 tainers, customers can see all the ber- 



ries they purchase, and the containers are inexpensive; 

 however, juice can accumulate at the bottom of them. 

 It is difficult to cool berries in any of these types, and 

 mold tends to develop on the lower berries. The slitted 

 plastic containers allow for rapid cooling, do not stain, 

 and do not accumulate juice; however, if the slits are 

 too wide, berries can be damaged. A narrowly slitted, 

 plastic, half-pint container with a plastic wrap is often 

 used by large wholesalers. 



Postharvest Considerations 



Much time and effort can be expended to produce 

 and harvest a good crop of berries, only to have the crop 

 deteriorate before it is sold. This deterioration is 

 caused by respiration of the fruit. Respiration occurs in 

 all living organisms and is the process by which food 

 reserves are converted into energy. In a complex series 

 of reactions, starches and sugars are converted first to 

 organic acids, then to more simple carbon compounds. 

 Oxygen from the surrounding air is used, and carbon 

 dioxide and heat are released. Respiration of fruits 

 results in shrinkage and reduced sweetness. Raspber- 

 ries and blackberries have a higher respiration rate 

 than any other fruits, while strawberries follow closely 

 on the list (Table 1). Raspberries respire as much at a 

 freezing temperature as oranges do at room tempera- 

 ture. Conditions which slow the respiration process 

 are low temperature, high carbon dioxide, and low 

 oxygen in the storage chamber. 



Temperature is the easiest and most effective con- 

 dition to modify for extended storage of fruits. Some 

 large shippers on the West Coast use a high carbon 

 dioxide atmosphere, and there have been some at- 

 tempts to use low oxygen storage, much like is done 

 with apples. In small fruits, however, bad-tasting 

 aldehydes and alcohols will accumulate in the fruit 

 when oxygen is limited. Work currently is being con- 



10 



Fruit Notes, Spring, 1990 



