Beverage Pasteurization Methods

08 Sep Beverage Pasteurization Methods

1. Tunnel / Flash Pasteurization

• Process: Coffee is heated rapidly to ~160–180°F (71–82°C) for a short time as it passes through a tunnel or flash pasteurizer.

• Effect on coffee compounds:

  • The heat can accentuate existing acids, especially chlorogenic acids, making the coffee taste sour or sharp.

  • The rapid heating can cause partial degradation of some sugars, which normally balance acidity, leading to a perception of sourness.

  • Proteins and oils in coffee can also denature or oxidize quickly, subtly changing mouthfeel and bitterness.

• Net result: The coffee can taste “bright” but also sour or acidic because there isn’t enough time or temperature control to stabilize the flavor.

2. Retort Processing

• Process: Retort involves heating the sealed product (often in a pouch or bottle) at higher temperatures (~250–270°F / 121–132°C) for a longer period to achieve commercial sterility.

• Effect on coffee compounds:

  • Longer, controlled heat allows Maillard reactions and mild caramelization, which smooths the acidity.

  • Acidity is balanced because the sugars and other flavor compounds have time to react and mellow the sharp acids.

  • Since the product is sealed, there’s minimal oxidation, which preserves flavor stability better than an open flash tunnel.

• Net result: Coffee tastes fuller, less sour, and often “rounder” because the heat has redistributed and mellowed acids and sugars.

Plate Pasteurization

• Process: Coffee flows through heated metal plates on one side, while cold water or the coffee itself flows on the other, creating direct heat transfer. Typical temps: 160–175°F (71–80°C) for short holding times (seconds to a few minutes).

• Effect on coffee flavor:

  1. Acidity: Similar to flash pasteurization, the rapid heating can accentuate acidic compounds (chlorogenic acids), giving some sourness, but usually less harsh than a tunnel pasteurizer because heat exposure is more controlled.

  2. Sugar balance: Minimal time for Maillard reactions or caramelization, so the coffee may lack the “rounded sweetness” that retort provides.

  3. Oils & mouthfeel: Because it’s gentle and precise, plate pasteurization preserves more of the coffee’s natural oils and body than flash tunnel pasteurization.

  4. Oxidation: Short exposure and closed piping minimize oxygen contact, so flavor degradation is limited

Impact of 12 oz Sleek Cans on Plate Pasteurization

1. Thermal Mass & Heat Transfer

   • Sleek cans have thin walls, so the coffee heats faster and more evenly than in glass or thick PET bottles.

   • Faster heat transfer can accentuate acidity if holding time isn’t carefully adjusted.

2. Headspace Considerations

   • Cans typically have very small headspace, which limits oxygen exposure—good for flavor stability.

   • Less oxygen means less oxidation-related sourness or off-flavors during storage.

3. Sealed Environment

   • Because cans are hermetically sealed immediately after filling, you get better preservation of volatile aroma compounds compared to bottles or pouches.

   • This helps maintain a “fresher” taste, even if acidity is slightly high.

4. Shelf Life

   • Plate pasteurization in cans can achieve 2–4 weeks of refrigerated shelf life, depending on temp and holding time.

   • Retort is overkill for a 12 oz cold brew can unless you need room-temperature shelf stability.

1. Why Plate Pasteurization Isn’t Enough for Room Temp

• Plate pasteurization is typically 160–175°F for seconds to a few minutes.

• At this temp, you kill most pathogens, but some spoilage microbes (like thermophilic bacteria or mold spores) can survive.

• Refrigerated shelf-life: 2–4 weeks—not room temperature.

2. Options for Room-Temp Shelf-Stable Cold Brew

A. Retort / Aseptic Filling

• Process:

  1. Cold brew is hot-filled or retorted in cans.

  2. High heat (~250°F / 121°C) kills all pathogens and spores.

• Pros:

  • 6–12+ months shelf-stable at room temp.

  • Smooths acidity (less sour).

• Cons:

  • Can slightly “cooked” the coffee flavor if not optimized.

B. Ultra-High Temperature (UHT) / Aseptic Coffee

• Coffee is heated above 275°F / 135°C for seconds and then filled into sterile cans or pouches.

• Preserves more coffee flavor than retort while still room-temp stable.

C. Preservatives + Mild Heat

• Adding natural preservatives (like ascorbic acid or potassium sorbate) and mild pasteurization can extend shelf life a few months.

• Limitation: Not truly long-term RTD; flavor may degrade over time.

3. pH Consideration

• Cold brew is naturally around pH 4.5–5.0, which is moderately acidic.

• Lowering pH slightly to ~4.3–4.5 helps inhibit bacterial growth in room-temp products.

• Combined with retort/UHT, this ensures safety without needing chemical preservatives.

4. 12 oz Cans Specific Notes

• Thin cans are excellent for heat transfer—retort/UHT is very efficient.

• Minimal headspace + hermetic seal = excellent flavor preservation.

• Heat treatment must be carefully controlled to avoid sour or “cooked” flavors.