Processing and Storage Effects on Berry Bioactives Luke R. Howard, Ph.D .

Phytonutrient/Phytochemical Components in a plant based diet other than traditional nutrients that can reduce the risk of degenerative diseases

Berries and Health Promotion Prevention of Chronic Diseases CHD & stroke Cancer Neurological disorders Obesity Type II diabetes Mechanisms Antioxidant Anti-inflammatory Cell signaling Gene regulation Apoptosis Modulation of enzymes

Free Radicals

Antioxidants

Fruit and Vegetable Phytochemicals Fruit and vegetable phytochemicals play an important role in health-promotion Due to limited shelf-life and seasonal availability, fruits and vegetables are commonly consumed in various processed forms How does processing impact phytochemical content?

Flavonoids

Procyanidins Epicatechin Procyanidin B2

Anthocyanin-Procyanidin Polymers a.k.a Polymeric Pigments

The Problem Phytochemicals losses are inevitable during fruit and vegetable processing Losses are due a number of processing, biochemical, and food matrix factors Losses can also occur during storage of processed products

Processing Factors Influencing the Stability of Phytonutrients Temperature (blanching and pasteurization) Light Oxygen Water (washing, soaking, canning) Physical removal of tissues

Thermal Degradation of Anthocyanins

Strawberry Puree Stored One Month at 25oC

Biochemical Factors Influencing the Stability of Phytonutrients Co-factors Metals Enzymes pH Ascorbic acid

Consequences of Cell Disruption PPO O2 PPO/POD POD + o-diphenols quinones ACY Phenolics Organic acids Sugars ascorbic acid degradation products ACY tannins + ACY mediators? polymers O2 tannins ACY tannins polymers ACY

pH Effect on Anthocyanin Structure

Food Matrix Factors Influencing the Stability of Phytonutrients Chemical structure/solubility Tissue localization: Free vs. bound Interactions among compounds

Light Microscopy of Cranberry Pomace Differential interference contrast (DIC) microscopy image of residue remaining after ground cranberry pomace was extracted with acetone:water:acetic acid (70:29.5:0.5) and stained with dimethylaminocinnamaldehyde (DMAC) at 20x magnification Differential interference contrast (DIC) microscopy image of residue remaining after ground cranberry pomace was treated with 2 N NaOH at 60 °C for 15 m and stained with dimethylaminocinnamaldehyde (DMAC) at 20x magnification

Procyanidin Oligomer (DP1 – DP6) Composition of Cranberry Pomace Before and After Treatment with Sodium Hydroxide

Properties of Phytonutrients in Plant Tissues Feature Carotenoids Phenolics Subgroups Lutein, α-carotene, β-carotene, zeaxanthin, β-cryptoxanthin Phenolic acids, hydroxycinnamates, flavonoids Solubility Lipid Water Cellular localization Associated with membrane protein, complexes in chloroplast or chromoplast Dissolved in vacuole and apoplast, some may be cell wall bound (not water soluble) Structural localization Some types preferentially in surface tissues like peel and outer pericarp Anthocyanins preferentially in peel; procyanidins in peel and seed; hydroxycinnamates in flesh, ellagitannins in seeds

Changes in Antioxidant Activity as Affected by Heating Nicoli et al. (1999) Trends Food Sci. Tech. 10:94-100

Food Matrix Interactions – Anthocyanin Co-pigmentation Intermolecular copigmentation Self-association Metal complexation Intramolecular copigmentation Aglycone Sugar Copigment Acid

Food Matrix Interactions – Binding of Procyanidins to Cell Wall Polysaccharides Le Bourvellec et al. (2009) Carbohydrate Polymers 75:251-261

Food Matrix Interactions – Binding of Procyanidins to Proteins Haslam (1998) Practical Polyphenolics: From structure to molecular recognition and physiological action. Cambridge University Press

Case Study: Processing Effects on Blueberry Polyphenolics

Case Study I Objectives To determine how different preservation methods (canning, pureeing, juicing) affect the retention of blueberry polyphenolics and antioxidant capacity To determine how storage of processed products affects the retention of blueberry polyphenolics and antioxidant capacity

Fresh Blueberries (cv. Bluecrop) Analysis of Fresh Berries Frozen Berries Individually Quick Frozen (IQF) Puree Juice Canning Baking Canned (Syrup) Canned (Water) Clarified Non-Clarified Pie-Canned in Water Pie-Frozen Berries Sampling: 1 d, 1 mo, 3 mo, 6 mo

Juice Processing Steps

Chemical Analysis Polyphenolics (anthocyanins, procyanidins, chlorogenic acid, flavonols) measured by HPLC Antioxidant capacity: ORACFL assay Polymeric color: Colorimetric assay, measures the amount of anthocyanin polymers

Polymeric Color Assay

Total Anthocyanin Retention and Polymeric Color in Blueberry Juices

Total Anthocyanin Retention and Polymeric Color in Canned Blueberries

Total Anthocyanin Retention in Blueberries Canned in Syrup

Total Anthocyanin Retention and Polymeric Color in Blueberry Puree

Total Flavonol Retention in Blueberry Juices

Total Flavonol Retention in Blueberries Canned in Syrup

Total Flavonol Retention in Blueberry Puree

Total Procyanidin Retention in Blueberry Juices

Total Procyanidin Retention in Blueberries Canned in Syrup

Total Procyanidin Retention in Blueberry Puree

Chlorogenic Acid Retention in Blueberry Juices

Chlorogenic Acid Retention in Blueberries Canned in Syrup

Chlorogenic Acid Retention in Blueberry Puree

ORACFL Retention in Blueberry Juices

ORACFL Retention in Canned Blueberries

ORACFL Retention in Blueberry Puree

Tissues Small intestine Liver Kidney Urine Dietary polyphenols Tissue metabolites Tissues Small intestine Liver bile Kidney Colon Urine Microbial metabolites Feces

Discussion Which processing, biochemical, and food matrix factors most likely played a role in polyphenolic losses during processing and storage of blueberry products? Why does the antioxidant capacity of stored products change little during storage despite losses of anthocyanins and procyanidins?

Discussion Continued What steps can processors take to minimize phytonutrient losses during processing and storage? What steps can consumers take to minimize phytonutrient losses following purchase of processed berry products? Would you expect processed berry products to have the same health benefits as fresh berries?