Pear: Anjou, Bosc & Comice
Maturity Indices Pear Anjou
Flesh firmness Pear Anjou is used as a maturity index as follows:
Flesh firmness (pounds – force) | ||||
Cultivar | Maximum | Optimum | Minimum | |
Anjou | 15 | 13 | 10 | |
Bosc | 16 | 13 | 11 | |
Comice | 13 | 11 | 9 | |
Other indices include corking of lenticels, pattern of starch content, and internal ethylene concentration.
Quality Indices
Appearance. color, size, shape, freedom from internal breakdown, black- ened, 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).
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
Temperature | 0°C(32°F) | 5°C(41°F) | 10°C(50°F) | 20°C(68°F) |
ml CO2/kg·hr* | 1 – 3 | 3 – 6 | 5 – 10 | 15 – 30 |
*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
Temperature | 0°C(32°F) | 5°C(41°F) | 10°C(50°F) | 20°C(68°F) |
µl/kg·hr* | 2 – 5 | 5 – 15 | 10 – 25 | 40 – 80 |
*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.