Articles
Maintaining almond (Prunus dulcis) quality for a warmer world
Article number
1353_23
Pages
183 – 196
Language
English
Abstract
Almonds are an excellent alternative to animal protein, dairy and wheat flours and consumption is linked to positive impacts on health.
California almonds are increasingly impacted by extreme weather patterns in response to climate change which includes more seasonal drought and heavy rain events (fall/winter). Water stress can increase levels of certain plant defense compounds including cyanogenic glycoside.
Almonds contain the cyanogenic glycoside amygdalin.
Hydrolysis of amygdalin results in the release of hydrogen cyanide (HCN) which is toxic.
Herein we discuss levels of amygdalin in major California almond cultivars from five crop seasons (2012-2020). Data indicate that amygdalin levels differ with cultivar, with averages ranging from 1 to 135 mg kg‑1. The highest levels are found in Aldrich and Fritz. Measured and estimated HCN levels correlate with amygdalin levels, with varietal averages ranging from 0.8 to 6.0 mg kg-1. The highest measured (10 mg kg‑1) and estimated HCN level based on the amygdalin content was 12.9 mg kg‑1. Both values are well below the proposed EU Food Safety Authority limit of 35 mg kg‑1. Elevated moisture content of in-hull almonds promotes kernel damage during processing (removal of hulls and shells) and increases the risk of lipid oxidation and rancidity development during storage.
Increasingly wet in-hull almonds are pre-dried before processing and kernel storage.
Wet in-hull almonds are vulnerable to potential of Salmonella contamination.
Although almond pasteurization is compulsory (since 2017), its effect on raw almond quality is not well understood.
Herein we discuss how in-field moisture exposure with pre-process drying, and moist heat (MH) or propylene oxide (PPO) pasteurization influence almond quality in relationship to lipid oxidation; the key determinant of shelf life and consumer acceptance.
Monitoring almond chemistry in response to changing environmental and postharvest processing is essential for sustainability of this popular food.
California almonds are increasingly impacted by extreme weather patterns in response to climate change which includes more seasonal drought and heavy rain events (fall/winter). Water stress can increase levels of certain plant defense compounds including cyanogenic glycoside.
Almonds contain the cyanogenic glycoside amygdalin.
Hydrolysis of amygdalin results in the release of hydrogen cyanide (HCN) which is toxic.
Herein we discuss levels of amygdalin in major California almond cultivars from five crop seasons (2012-2020). Data indicate that amygdalin levels differ with cultivar, with averages ranging from 1 to 135 mg kg‑1. The highest levels are found in Aldrich and Fritz. Measured and estimated HCN levels correlate with amygdalin levels, with varietal averages ranging from 0.8 to 6.0 mg kg-1. The highest measured (10 mg kg‑1) and estimated HCN level based on the amygdalin content was 12.9 mg kg‑1. Both values are well below the proposed EU Food Safety Authority limit of 35 mg kg‑1. Elevated moisture content of in-hull almonds promotes kernel damage during processing (removal of hulls and shells) and increases the risk of lipid oxidation and rancidity development during storage.
Increasingly wet in-hull almonds are pre-dried before processing and kernel storage.
Wet in-hull almonds are vulnerable to potential of Salmonella contamination.
Although almond pasteurization is compulsory (since 2017), its effect on raw almond quality is not well understood.
Herein we discuss how in-field moisture exposure with pre-process drying, and moist heat (MH) or propylene oxide (PPO) pasteurization influence almond quality in relationship to lipid oxidation; the key determinant of shelf life and consumer acceptance.
Monitoring almond chemistry in response to changing environmental and postharvest processing is essential for sustainability of this popular food.
Authors
A.E. Mitchell, G. Huang, K.K. Luo
Keywords
amygdalin, cyanogenic glycosides, moisture, lipid oxidation, shelf life, pasteurization
Groups involved
- Division Temperate Tree Fruits
- Division Temperate Tree Nuts
- Division Vegetables, Roots and Tubers
- Division Plant-Environment Interactions in Field Systems
- Division Horticulture for Human Health
- Division Postharvest and Quality Assurance
- Division Sustaining Horticulture in a Changing World
- Division Tropical and Subtropical Fruit and Nuts
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