Whole-cell Porphyridium red microalgae as a natural colorant for extruded foods

Overview

MicroBio Engineering offers whole-cell biomass of the marine red microalga Porphyridium purpureum as a natural red-to-brown colorant for extruded foods. The algal cells naturally contain phycoerythrin, a red phycobiliprotein, and are surrounded by a sulfated, high-molecular-weight polysaccharide capsule. The biomass can be used as a frozen paste, homogenized, or dried and fed directly into food formulations—no pigment extraction, derivatization, or chemical modification is required.

This solution addresses the demand for clean-label natural food colors. Compared with betanin, the incumbent beet-derived colorant, phycoerythrin faded more slowly at elevated temperatures and retained more red at higher pH in solution tests. The whole-cell format lowers cost and complexity by avoiding downstream processing, and the natural polysaccharide capsule may help protect the pigment during processing. The weak cell wall and low lipid content also help limit texture and off-flavor risks. Production cost is projected at roughly $1–2/kg at mature scale, supported by a valuable polysaccharide co-product.

Technical specifications

Key features:

• Whole-cell Porphyridium purpureum biomass with 2–5% phycoerythrin by dry weight
• Available as frozen 10–15% solids paste in kilogram quantities; homogenized and dried forms planned for evaluation
• Cultivated outdoors in open ponds on brackish water and waste CO2
• No extraction, derivatization, or chemical modification
• Heat-driven shift from red toward brown, suitable for brown and red-brown extruded food targets
• Co-product polysaccharide with potential value as a cosmetic hyaluronic acid analog

Planned proof-of-concept parameters:

• Inclusion rates of 0.5–5% on a dry basis in a tan extruded base
• Extrusion barrel temperatures from 75–150 °C
• Measurements include CIE Lab* color, expansion, bulk density, hardness, torque, and die pressure
• Accelerated storage testing and sensory screening
• Cost-in-use estimated at the measured inclusion level

A green microalga may also be explored as an additional color option.

Technology readiness level

The technology is at an early stage. Laboratory-scale stability testing has shown promising heat and pH performance relative to betanin, and the alga has been cultivated outdoors for 83 days without culture loss. Kilogram quantities of frozen biomass are available for evaluation.

A three-month proof-of-concept extrusion trial is planned to validate color performance, processing impact, storage stability, and cost-in-use. Success criteria include a target color shift at or below 3% inclusion, less than 10% change in expansion and hardness, and color retention after three months of accelerated storage. Follow-on work would include dried kilogram-scale supply, regulatory assessment, a 12-month ambient stability study, and scale-up planning.