Pear, Anjou, Bosc, Comice

MATURITY & QUALITY

Maturity Indices

Flesh firmness is used as a maturity index as follows:

Other indices include corking of lenticels, pattern of starch content, and internal ethylene concentration.

Quality Indices

• Appearance. color, size, shape, freedom from internal breakdown, blackened, russeting (presence or absence), bruising, scars, sunburn, insect damage, and other defects.
• Texture. firmness of the flesh, presence of sclereid cells.
• Flavor. taste related to contents of sugars and organic acids; aroma which is dependent upon volatiles (production may be enhanced by ethylene treatment during ripening of pears).

TEMPERATURE & CONTROLLED ATMOSPHERE (CA)

Optimum Temperature

-1 to 0°C (30 to 32°F); freezing temperatures are -1.5° to -2°C (29 to 28°F)

Optimum Relative Humidity

90-95%

Rates of Respiration

*Low end for ‘Anjou’ and high end for ‘Bosc’ and ‘Comice’ pears.
To calculate heat production, multiply ml CO₂/kg hr by 440 to get Btu/ton/day or by 122 to get kcal/metric ton/day.

Rates of Ethylene Production

*Low end for ‘Anjou’ and high end for ‘Bosc’ and ‘Comice’ pears.

Responses to Ethylene

Treating pears with 100 ppm ethylene for 1 to 2 days can substitute for cold storage [4 to 8 weeks at -1° to 0°C (30 to 32°F)] in enhancing ripening. Optimum conditions for ripening are 15 – 22°C (59-72°F; the higher the temperature the faster the ripening) and 90-95% relative humidity; CO₂ should be kept below 1%.

Responses to Controlled Atmospheres (CA)

Optimum range: 1-2% O₂ + 0-1% CO₂

Winter pear varieties can be stored in CA at -1°C (30°F) for up to 4 months (Bosc & Comice) or 6 months (Anjou) while maintaining their capacity to ripen and attain good flavor and texture.

Oxygen levels below 1% and/or carbon dioxide above 1% for longer than two weeks can induce physiological disorders; severity increases with lower 0₂%, higher CO₂%, higher temperatures, and longer storage time.