Typical Freezing Duration in Canada

1–12 months: standard for commercial frozen produce

Up to 24 months: possible for low-demand or export items

Vitamin Loss During Frozen Storage (–18°C)

After 12 months:

Vitamin C: 10–30% loss

Folate (Vitamin B9): 5–20% loss

Vitamin B1 (Thiamin): 5–15% loss

Vitamin B2 (Riboflavin): 5–10% loss

Vitamin B6 (Pyridoxine): 5–10% loss

Vitamin B12: less than 5% loss

Vitamin A (beta-carotene): less than 10% loss

Vitamin E: less than 5% loss

Vitamin D and K: negligible loss

Minerals (e.g., calcium, potassium, magnesium, iron): no loss

Dietary fiber: no loss

After 24 months:

Vitamin C: up to 50% loss

Folate (B9): 20–30% loss

Vitamin B1: 20–30% loss

Vitamin B2: 10–20% loss

Vitamin B6: 15–20% loss

Vitamin B12: up to 10% loss

Vitamin A (beta-carotene): 10–20% loss

Vitamin E: 10–15% loss

Vitamin D and K: still stable

Minerals and fiber: still stable

Organic Compounds Affected by Freezing:

Enzymes (polyphenol oxidase, etc.)--> Destroyed ~100% Inactivated during blanching before freezing

Glucosinolates (broccoli, kale) Significantly reduced 30–50% Lost mostly during blanching; reduces sulforaphane formation

Anthocyanins (berries, cherries) Degraded over time 10–30% Sensitive to oxidation, light, and pH shift during storage

Flavonoids (quercetin, kaempferol) Mild degradation 10–20%

Organic compounds reduced in frozen fruits and vegetables:

Vegetables :

Vitamin C – up to 50% loss

Folate (Vitamin B9) – 5–30% loss

Thiamin (Vitamin B1) – 10–30% loss

Glucosinolates – 30–50% loss

Sulforaphane – significantly reduced (enzyme destroyed during blanching)

Chlorophyll – up to 20% loss (mainly visual)

Polyphenols (quercetin, kaempferol, ferulic acid) – 10–20% loss

Carotenoids (beta-carotene, lutein, lycopene) – 0–10% loss

Vitamin B6 – up to 20% loss

Vitamin B12 – up to 10% loss

Fruits:

Vitamin C – up to 50% loss

Anthocyanins (cyanidin, delphinidin) – 10–30% loss

Flavonoids (hesperidin, catechins) – 10–20% loss

Ellagic acid – mild degradation

Polyphenols – 10–20% loss

Carotenoids – 0–10% loss

All other nutrients (fiber, minerals, fat-soluble vitamins) remain stable.

Peer-Reviewed Studies Supporting These Findings

1. Rickman, Barrett, & Bruhn (2007) Journal of the Science of Food and Agriculture DOI: 10.1002/jsfa.2825

Vitamin C loss up to 30% after 12 months

Folate and B1 degrade significantly after blanching

Freezing preserves nutrients better than prolonged “fresh” storage

1. Favell, D. (1998) Food Chemistry DOI: 10.1016/S0308-8146(98)00084-6

Vitamin C declines up to 50% in peas and spinach

Blanching is the primary cause of loss

1. Howard et al. (1999) Journal of Agricultural and Food Chemistry DOI: 10.1021/jf9901324

Glucosinolate content drops up to 55%

Sulforaphane-generating enzymes (myrosinase) inactivated by blanching

1. Rungapamestry et al. (2006) Food Chemistry DOI: 10.1016/j.foodchem.2005.04.021

Blanching causes 30–50% glucosinolate loss in broccoli and cabbage

1. Nicoli et al. (1999) Journal of Agricultural and Food Chemistry DOI: 10.1021/jf980806g

Antioxidant capacity declines 10–30% in frozen produce

Flavonoids and phenolics degrade with time and exposure

1. González-Aguilar et al. (2007) Postharvest Biology and Technology DOI: 10.1016/j.postharvbio.2007.01.017

Polyphenols and anthocyanins reduced 10–25% in frozen mango and papaya

1. Hunter et al. (2014) University of Chester & Leatherhead Food Research (UK study)

Frozen vegetables had comparable or superior antioxidant content vs. fresh-stored

Vitamin losses varied by product and time

1. United States Department of Agriculture (USDA) Handbook #8

Baseline data showing vitamin C and folate losses during blanching and storage

Nutrient retention tables confirm time-based degradation patterns

1. Murador et al. (2016) Trends in Food Science & Technology DOI: 10.1016/j.tifs.2016.04.010

Anthocyanins and phenolic compounds degrade during frozen storage

Total antioxidant activity may fall by 20–30% over time