Chapter 38 — Exercises and Kitchen Labs

This chapter is unusual: many of the technologies it describes have not arrived in your kitchen yet. The labs that follow are designed to give you direct, hands-on experience with the parts of the future kitchen that have arrived — plant-based meats, microbial protein, precision-fermented rennet — and to let you see, with your own taste buds, what is actually different about these foods, what is similar, and how the science of cooking carries through.

The discussion questions extend the chapter's themes into classroom and self-study contexts. The advanced sidebars expand on the engineering and biology in more depth than the main chapter could accommodate.

Kitchen Lab 38.1 — A Three-Way Burger Tasting

Goal: Compare a conventional ground-beef patty, a high-quality plant-based patty, and (if available) a cultured-meat product, on flavor, texture, mouthfeel, and "meatiness."

Time: About 45 minutes including setup.

Materials: - Conventional ground-beef patty, 80/20 fat ratio, 4 oz / 113 g - Plant-based patty (Impossible, Beyond, or local equivalent), 4 oz / 113 g - Cultured-meat patty, 4 oz / 113 g — if available; rare in 2026, more common in 2030 - Cast-iron or heavy stainless skillet - Neutral high-heat oil (canola, grapeseed, refined avocado), 1 tablespoon (15 mL) - Salt and pepper - Plain bun, lettuce, tomato — same accompaniments for all three - Notepad and pen — or rubric sheet, classroom version below - Optional: blindfolds, aluminum foil to mask appearance

⚠️ Allergen flags. Plant-based patties typically contain soy, wheat, or pea protein, depending on brand. Some contain coconut oil. Cultured-meat products may contain mammalian proteins (beef, chicken, pork). Check labels for individual products. Anyone with severe meat or soy allergies should not participate.

⚠️ Safety. Cook all patties to safe internal temperatures: ground beef to 71°C / 160°F minimum; plant-based and cultured products per package directions, typically 74°C / 165°F. Use a probe thermometer.

Setup:

Identify the three patties to a helper, who marks them A, B, and C and brings them to the cooking station out of your sight. (Or have everyone wear blindfolds during tasting; appearance differences are obvious otherwise.)

Procedure:

  1. Heat the skillet over medium-high heat for 3 minutes.
  2. Add 1 teaspoon (5 mL) oil. Cook the first patty: 3 minutes per side, no pressing, with salt and pepper at the start of cooking. Use a probe thermometer to confirm the patty has reached safe internal temperature.
  3. Remove the patty to a plate. Wipe out the skillet. Repeat for the second and third patties, in randomized order.
  4. Construct three identical sandwiches: bun, patty, lettuce, tomato. No sauces, no cheese, nothing that would mask the patty.
  5. Sample each sandwich. Score on a scale of 1–10 for: flavor, texture, fat / mouthfeel, aroma, overall meatiness.
  6. After scoring, reveal which patty was which.

Expected results:

Most tasters find the conventional ground beef has the strongest beef-aroma signature (specifically the volatile compounds 2-methyl-3-furanthiol and bis(2-methyl-3-furyl) disulfide, which dominate beef aroma). The plant-based patty browns convincingly in the pan and has a similar (though not identical) aroma profile, mostly due to soy leghemoglobin or beet-derived heme catalyzing Maillard browning. Texture differences are usually the most noticeable: the plant patty is often slightly more uniform and less juicy, while the conventional beef has more variable texture from the fat distribution.

The cultured-meat patty (if you can obtain one in your region) typically falls between the two on most measures — meaty in flavor, but somewhat leaner than conventional ground beef, with a cleaner mouthfeel that some tasters describe as "more uniform" and others as "less complex."

Troubleshooting:

  • All three patties taste the same: You may have added a sauce or cheese that is masking the differences. Repeat plain.
  • The plant-based patty fell apart in the pan: Plant patties have less collagen, so they need less flipping and less pressing. Cook longer per side without disturbing.
  • The patties tasted dry: All three should be cooked to the safe internal temperature, not beyond. A probe thermometer matters here.

Discussion:

After the reveal, discuss: what specific qualities did each patty have? What surprised you? If price were equal, which would you choose? If price were not equal, how much premium would you pay for which?

Kitchen Lab 38.2 — Cooking with Mycoprotein

Goal: Explore mycoprotein (Quorn) as a cooking ingredient. Compare its behavior to chicken in two cooking methods.

Time: About 30 minutes.

Materials: - Quorn frozen pieces or fillets, 8 oz / 227 g — available in roughly 30 countries; check freezer aisle of a midsize grocery - Boneless skinless chicken breast or thigh, 8 oz / 227 g - Skillet - 2 tablespoons (30 mL) neutral oil - Salt - 1 cup (240 mL) chicken or vegetable broth - 1 sprig fresh thyme or herb of choice

⚠️ Allergen flags. Quorn contains mycoprotein (Fusarium-derived). Some Quorn formulations also contain egg white as a binder; check label. Chicken is, of course, chicken.

Procedure A — pan-sear:

  1. Cut both proteins into similar bite-size pieces (about 2 cm cubes).
  2. Pat dry with paper towels.
  3. Heat the skillet over medium-high heat. Add 1 tablespoon (15 mL) oil.
  4. Sear the Quorn pieces, single layer, undisturbed for 2 minutes. Flip; sear another 2 minutes. Salt to taste. Remove.
  5. Wipe skillet, add another tablespoon oil. Sear the chicken pieces, 3–4 minutes per side, until internal temperature reaches 74°C / 165°F. Salt to taste.

Procedure B — simmer:

  1. Bring the broth to a simmer with the herb. Add half of the remaining Quorn pieces; simmer 8 minutes. Remove with slotted spoon.
  2. Add half the remaining chicken pieces to the same broth; simmer 10 minutes or until cooked through.

Compare:

  • Pan-sear: Did the Quorn brown? (It should — the Maillard reaction works on mycoprotein because it contains free amino acids and reducing sugars, similar to meat.) How does the texture compare to the chicken? Most tasters report the Quorn is slightly more uniform in texture, less variation in fiber direction, but recognizably "meat-like."
  • Simmer: How did each protein absorb the broth? Mycoprotein, with its filamentous fungal structure, often absorbs flavor very well because the surface area and pore structure of fungal hyphae provides excellent absorption. Some tasters prefer the simmered Quorn to the simmered chicken in this comparison.

Discussion:

The mycoprotein in Quorn is the same fungus (Fusarium venenatum) used since 1985, grown in continuous-culture bioreactors. The product has a very long track record. What surprises you about how it cooks? Does it change your impression of "alternative protein" from a marketing concept to a real ingredient?

Kitchen Lab 38.3 — Cultured Rennet vs. Animal Rennet Cheese

Goal: Make two side-by-side ricotta-style cheeses, identical except for the rennet source. Test whether you can taste the difference.

Time: About 90 minutes including resting; very simple procedure.

Materials: - Whole milk (not ultra-pasteurized; standard pasteurized works), 2 quarts / 1.9 L total — split into two 1-quart / 950 mL portions - 2 tablespoons (30 mL) lemon juice or white vinegar — for the acidification step; both batches use the same acid - Microbial / vegetarian rennet tablet, ¼ tablet — available at homebrew/cheesemaking suppliers; this is precision-fermented chymosin from Aspergillus or yeast - Animal rennet liquid, ¼ teaspoon — from a cheesemaking supplier; calf-stomach extract - 2 thermometers - 2 fine-mesh strainers lined with cheesecloth - 2 large bowls - Salt - Notebook for tasting notes

⚠️ Allergen flag. Dairy. Anyone with milk allergy or severe lactose intolerance should not participate.

🔗 This lab connects directly to chapter 32 (cheese, yogurt, cultured foods) and chapter 13 (enzymes). The whole point of the chapter 38 framing is that most cheese on supermarket shelves in 2026 is already made with precision-fermented chymosin, and almost no consumers can tell. This lab tests that claim with your own palate.

Procedure:

  1. Label two pots: BATCH A (microbial rennet) and BATCH B (animal rennet).
  2. Heat both pots of milk to 85°C / 185°F, stirring gently to prevent scorching.
  3. Remove from heat. Add 1 tablespoon (15 mL) lemon juice to each pot. Stir once.
  4. Dissolve the microbial rennet tablet in 1 tablespoon (15 mL) cool unchlorinated water; stir into Batch A.
  5. Add the liquid animal rennet (1/4 teaspoon, no dilution needed) to Batch B.
  6. Cover both pots; let stand undisturbed for 30 minutes.
  7. The milk should have separated into curds (white solids) and whey (pale yellow liquid).
  8. Pour each batch through its own cheesecloth-lined strainer over its own bowl. Let drain 15 minutes.
  9. Salt each batch lightly (¼ teaspoon / 1 g per batch). Refrigerate.

Tasting:

  1. Taste both fresh, in random order, ideally with a helper revealing identities only after scoring. Score on flavor, texture, "milkiness," and any other descriptors.
  2. Repeat tasting after 24 hours of refrigeration.

Expected results:

Most tasters cannot reliably distinguish the two cheeses in blind tasting. The chymosin produced by precision fermentation is biologically identical to calf chymosin in its enzymatic action; the resulting cheeses have very similar protein structure, texture, and flavor. Differences, if any, are usually small enough to fall within the noise of batch-to-batch variation in milk.

The point:

The point is not that the two cheeses are exactly identical — there may be subtle differences. The point is that an entire global cheese industry transitioned to precision-fermented chymosin over the last forty years, and almost no consumers noticed. This is the future of food technology happening in a way that is mostly invisible.

Kitchen Lab 38.4 — Reading a Food-Tech Press Release

Goal: Develop the skill of distinguishing what a food-technology company is actually claiming from what its marketing language sounds like it is claiming.

Time: 30–60 minutes.

Materials:

A recent press release from a food-technology company — cultured meat, precision fermentation, plant-based, vertical farming, anything in this space. Many are easily found via the company websites or via search terms like "cultured meat press release 2025."

Procedure:

  1. Read the press release once, normally.
  2. Read it again, with a highlighter. Mark every quantitative claim (numbers, percentages, comparisons) in one color, every qualitative claim (descriptions of taste, sustainability, etc.) in another, and every quotation from an executive in a third.
  3. For each quantitative claim, ask: what is the source of this number? Is it cited? Is it from peer-reviewed research, an internal company analysis, or a third-party consultant?
  4. For each qualitative claim, ask: what would falsify this? If the claim is "as good as conventional meat," what test, in principle, would prove the claim wrong?
  5. For each executive quotation, ask: would a competitor disagree with this? Aspirational statements that no one would oppose are usually decorative.

Expected results:

Most food-tech press releases contain a small number of substantive technical claims, embedded in a large amount of marketing language. The substantive claims are often quite specific (a particular cost reduction, a particular regulatory milestone, a particular partnership) and often quite modest. The marketing language is what generates headlines.

This skill — distinguishing the hard claims from the soft language — is the same skill chapter 37 tried to build for nutrition headlines. It applies broadly.

Discussion Questions

  1. The Aroon question. Aroon Sornprasit's line in this chapter is new ingredient, same cook. What does that mean to you? Does it generalize? Are there any new food technologies that genuinely change what cooking is, rather than just adding ingredients to it?

  2. Precision fermentation and consumer perception. Recombinant chymosin has been the dominant rennet in cheese for decades, and most consumers don't know. Is the lack of disclosure ethically appropriate, given that the final product contains no genetically modified organisms? Or should every product disclose its production technology, even when the technology produces a chemically identical molecule?

  3. The land-use argument. If cultured meat were genuinely produced with renewable energy and used a tenth the land of conventional beef, would you switch? At what price premium? At what flavor cost?

  4. Indigenous food sovereignty. The chapter raised the question of whose voices are at the table when "the future of food" is designed. What would it mean, concretely, for cultured meat or precision fermentation to be deployed in a way that respects food sovereignty? Whose decision is it?

  5. The grandmother question. Aroon and Maya both bring up the figure of the grandmother — a person who fed a family from local sources, knew the producers by name, and did not consult studies or bioreactors. Is the grandmother nostalgic, or is she a model? What survives, in the kitchen of the future, of the kitchen of the past?

  6. The arithmetic problem. Agriculture occupies 50% of habitable land, uses 70% of fresh water, and contributes about 25% of greenhouse gas emissions, while feeding everyone. If you had to choose three interventions to bring those numbers down, which would you choose, and why? (Cultured meat? Reduced meat consumption? Climate-adapted crops? Vertical farming? Reduction in food waste? Something else?)

  7. Generational change. Maya's nephew Tobi, eleven years old in 2026, is enthusiastic about cultured meat. Maya's mother, eighty-three in 2026, finds it disorienting. What conversations should happen in households across this generational gap? What can each generation teach the other?

  8. Regulatory divergence. The United States and the European Union have classified CRISPR-edited foods very differently. The science is the same; the regulations differ. Should regulators harmonize, and if so, around which approach? Or is regulatory divergence a feature, not a bug?

  9. The chef's role. Aroon predicts that future chefs will work with new ingredients and continue to cook traditional foods alongside them. Is that a sustainable model, or will the new ingredients eventually displace the old? What economic and cultural conditions favor preservation of traditional foods?

  10. Ultra-processed foods, again. Many of the technologies in this chapter — plant-based meats, precision-fermented dairy proteins, microbial protein — produce highly processed foods. Chapter 37 discussed the evidence on ultra-processed foods. How do you reconcile the environmental advantages of these products with the (still-uncertain) nutritional concerns about ultra-processing?

Advanced Sidebars Expanded

Bioreactor scale-up: the engineering numbers

A working brewery fermenter holds 200,000 to 1,000,000 liters and produces beer at densities approaching 50 grams of yeast solids per liter. The cells are tolerant of moderate shear, low oxygen, ethanol concentrations up to 12% v/v, and temperatures up to 35°C. The whole system is designed around the cells' robustness.

A mammalian cell bioreactor at production scale today is typically 2,000 to 20,000 liters and produces cells at densities of 5 to 20 grams of cell solids per liter at peak. The cells require pH buffering (typically by sparging CO₂), dissolved oxygen control (40–60% saturation), temperature control to 37°C ± 0.5°C, low shear (specialized impellers, surface aeration via silicone membranes), and continuous removal of metabolic waste products via perfusion. Each of these requirements adds capital cost and operational complexity.

The fundamental ratio: a kilogram of yeast can be produced in a brewery for a few cents in feedstock cost. A kilogram of mammalian muscle cells, in 2025, costs on the order of tens of dollars in feedstock and process costs combined, mostly driven by growth medium. The trajectory is downward, but the floor is set by biology — cells doubling every 24+ hours cannot, in principle, be made to double in 90 minutes.

CRISPR-Cas9 in food applications: mechanism

The CRISPR-Cas9 system has two components:

  • A guide RNA (gRNA), typically 20 nucleotides long, designed to be complementary to a target DNA sequence in the genome.
  • The Cas9 protein, a DNA endonuclease that uses the gRNA to recognize and bind to its target, then cleaves both strands of the DNA at a defined position.

The cut DNA triggers the cell's repair machinery, which can take two paths:

  • Non-homologous end joining (NHEJ) is fast and error-prone; it usually rejoins the DNA with small insertions or deletions at the cut site. This is how gene knock-outs are made (you disrupt the gene's reading frame).
  • Homology-directed repair (HDR) is slow and accurate; if a template DNA matching the cut site is provided, the cell can use it to make a precise edit (a single base change, or insertion of a defined sequence). This is how precision edits are made.

In food applications:

  • The non-browning button mushroom uses NHEJ-based knock-out of polyphenol oxidase. No foreign DNA is inserted.
  • Low-acrylamide potatoes use NHEJ-based knock-out of asparagine synthetase, reducing the precursor that forms acrylamide during high-temperature cooking.
  • Several CRISPR-edited tomatoes target genes affecting fruit ripening, color, or shelf life.

Regulatory frameworks have differed sharply on whether to classify these foods as conventional GMOs:

  • The US Department of Agriculture has generally taken the position that NHEJ-based edits without inserted foreign DNA are not subject to GMO regulation.
  • The European Union, after a 2018 European Court of Justice ruling, classified all CRISPR-edited crops as GMOs, requiring full regulatory approval.
  • Several other jurisdictions have intermediate or evolving positions.

The regulatory question is, fundamentally, about whether to regulate the process (how the change was made) or the product (what the resulting organism is). The process-vs-product debate has been running in biotech regulation for over thirty years. CRISPR has made it more urgent.

Growth media and the serum problem

The growth medium is the most expensive part of cultured meat production, historically, and it remains the dominant cost driver in 2026. Understanding what is in a growth medium and why explains a great deal about why cultured meat costs what it costs.

A working mammalian cell growth medium contains, in approximate order of mass:

  • A basal salt solution providing balanced osmolarity and physiological pH (sodium chloride, potassium chloride, calcium chloride, magnesium sulfate, sodium bicarbonate, sodium phosphate). Cheap; pennies per liter.

  • Glucose as the primary carbon and energy source. Cheap. Cells consume glucose during growth.

  • Amino acids — typically all twenty proteinogenic amino acids in defined concentrations. Cheap when produced industrially. Some are sourced from microbial fermentation themselves (lysine, threonine, glutamic acid).

  • Vitamins and trace elements — biotin, riboflavin, B12, folate, choline, inositol, iron, copper, zinc, selenium, and a long list of others. Modestly expensive but well-defined.

  • Buffering capacity — sodium bicarbonate or HEPES buffer to maintain pH around 7.4 against the cells' production of lactic acid.

  • Growth factors — small protein hormones that signal cells to divide. The major ones for muscle stem cells include FGF (fibroblast growth factor, several variants), TGF-β (transforming growth factor beta), insulin or IGF (insulin-like growth factor), and several others. Each is normally present at nanogram-per-milliliter concentrations. Their production cost, by recombinant-protein methods, has been the major focus of cost reduction in cultured meat over the past decade. Five years ago, growth factors were tens of thousands of dollars per gram; today, leading suppliers are pricing in the hundreds of dollars per gram, and several are working toward dollar-per-gram targets.

  • Albumin (typically bovine serum albumin or recombinant human albumin) as a stabilizer and lipid carrier. Modestly expensive.

The replacement of fetal bovine serum with chemically-defined alternatives is one of the field's biggest victories. FBS used to dominate the cost of cell culture media (often 50–90% of total cost) and was the major obstacle to scaling cultured meat. Companies including Future Fields (Canada), Defined Bioscience, and others have developed precision-fermentation-based alternatives that produce the key growth factors at a fraction of the historical cost. The current trajectory has cultured meat media costs falling from thousands of dollars per liter (10 years ago) to single-digit dollars per liter (within five years, projected). At a few dollars per liter, the math starts to work for some products.

Fermentation biology, revisited

Chapter 30 introduced the basic biology of fermentation. In the context of precision fermentation and microbial protein, several points are worth emphasizing:

  • Engineered microbes are not "fermentation" in the classical sense. Classical fermentation produces a desired end product (alcohol, lactic acid, vinegar) as a metabolic byproduct of the microbe's normal life. Precision fermentation uses microbes as factories: the microbe is engineered to produce a protein it would not naturally produce, and that protein is the desired product. The "fermentation" is a misnomer of convenience.
  • Microbial protein (Quorn, Solein) is closer to classical fermentation in spirit: the microbe itself is the product. The fungus or bacterium is grown, harvested, and consumed.
  • The host organisms of choice for precision fermentation include Saccharomyces cerevisiae (baker's yeast, well-understood, food-safe), Pichia pastoris (a yeast favored for high-density growth), Trichoderma reesei (a mold with very high secretion capacity), and Escherichia coli (a bacterium with the most-developed genetic toolkit, though some food applications avoid it for regulatory or perception reasons).
  • The choice of host matters for regulatory pathway (what is considered "food-safe"), for cost (different organisms have different growth rates and yields), and for the structure of the final protein (post-translational modifications differ between organisms, which can affect protein function and immunogenicity).

Mastery Food Checkpoint

The mastery food tracks for chapter 38 are: chocolate, cheese, bread, fermented vegetables, coffee.

🥖 Bread track: The future of bread is partly conservative — sourdough baking, ancient grains, regional flours — and partly engineered. CRISPR-edited wheat varieties with reduced gluten reactivity are in research. Climate-adapted wheat varieties are critical for bread security in a warming world. Precision-fermented enzymes (amylases, proteases) are already standard in industrial bread production; "clean label" is a regulatory category, not a chemistry one.

🥖 Cheese track: Forty years of precision-fermented chymosin has given us this chapter's most concrete example. The next wave is whole-protein dairy — Perfect Day's casein and beta-lactoglobulin enable cheeses without cows. The cheesemaker's craft applies; the milk is the variable. Aged cheeses based on precision-fermented proteins are an open research question. Many fresh and short-aged styles already work.

🥖 Chocolate track: Chocolate is not yet a major target of cell-cultured production, but two developments matter. First, several startups are working on fermenter-grown cocoa — using microbial fermentation of cocoa-pulp-equivalent media to produce chocolate flavors without cocoa beans. Second, the underlying problem of cocoa is climate: cacao requires specific tropical conditions, and climate change is shrinking the viable cacao-growing zone. Climate-adapted cacao varieties are being developed by the Costa Rica-based research center CATIE and others.

🥖 Fermented vegetables track: Lacto-fermentation is, from one angle, the original "natural alternative protein" — using microbial communities to transform plant matter into nutritionally and microbiologically distinct foods. The future of fermented vegetables is partly a return to traditional methods (small-batch ferments with diverse microbiota) and partly a forward-looking integration with the gut-microbiome science discussed in chapter 37.

🥖 Coffee track: Lab-grown coffee, produced by culturing coffee plant cells in bioreactors, has been demonstrated by Finnish researchers (VTT) and is at pilot scale. The cultured coffee compares favorably to conventional in early sensory tests but is not yet at commercial scale. The ethical complexity is significant: coffee is grown by an estimated 25 million smallholder farmers worldwide, primarily in Latin America, Africa, and Southeast Asia, and a successful lab-grown alternative could displace livelihoods. The future-of-food question, in coffee's case, is unusually loaded.