Most failed prototypes do not fail because the recipe was weak. They fail because nobody wrote down what “good” meant before the first batch, so every tasting moved the target. A gated method fixes that: each step ends with a pass condition that is set before the trial and decided by a test, not by opinion.
This guide sets out the six steps Food Research Lab formulators use to take a brief to a stable prototype, the gate that closes each step, and the decisions that sit behind them. For the wider journey from idea to launch, see our food product development process guide; this article covers the formulation stage in depth.
A recipe lists ingredients and steps. A formulation is an engineered formula: ingredient weights to a fixed basis, process yields, and targets for pH, water activity, texture, cost and claims, written so another team can reproduce it at scale. The difference shows up the first time a batch is made by someone else, on other equipment, with a new lot of raw material.
In food product development, formulation sits between the approved concept and the pilot batch. Stage-gate models describe what happens in each stage; the method below adds the targets, tests, documents and go/no-go decisions that sit between a brief and a prototype that holds its quality over its shelf life.
Turn every adjective in the brief into a number and a test. “Soft” becomes a hardness range on a texture analyser; “long life” becomes a shelf-life target with a storage condition and an end point. Hold the result in a specification sheet as a target product profile (TPP), give each field a tolerance (for example, pH 4.2 ± 0.1), and start the bill of materials (BOM).
pH and water activity (aw) decide the safety category and much of the stability strategy, so set them first. US rules use pH 4.6 and aw 0.85 as boundaries: low-acid foods have a finished equilibrium pH above 4.6 and aw above 0.85, acidified foods are low-acid foods with added acid that reach pH 4.6 or below at aw above 0.85, and acid foods have a natural pH of 4.6 or below.[3] Moving a product across one of these lines changes its process controls, so decide the category at the brief, not after tasting. Claims work the same way: a protein or sugar claim sets a composition threshold that the formula must meet with margin, after process losses.
| Field | Define as | Test |
|---|---|---|
| Composition and claims | Nutrient targets per serving; claim thresholds with margin | Proximate analysis |
| pH and water activity | Target and tolerance (aw = equilibrium relative humidity ÷ 100) | pH meter, aw meter |
| Texture and sensory | Range and acceptance target | Texture analysis, hedonic panel |
| Cost-in-use | Target per kg of finished product (formula in Step 2) | Bill-of-materials costing |
| Shelf life | Target, storage condition, end point | Stability plan |
Gate 1: a signed specification in which every target has a number, a tolerance and a test.
Choose ingredients by function first and supplier second, because each function decides texture, stability or cost. Hydrocolloids, for example, are used to thicken, gel and stabilise emulsions and dispersions, while most plant-protein gels are sensitive to pH, temperature and ionic strength, which is why a protein swap often needs a hydrocolloid or process change alongside it.[1]
| Function | Ingredient class | What to check |
|---|---|---|
| Structure, water binding | Hydrocolloids | Thickening, gelling and emulsion stability; plant-protein gels respond to pH, temperature and ionic strength[1] |
| Bulk, sweetness | Sugars, polyols | Effect on water activity and on hardening during storage |
| Body, nutrition | Proteins | Solubility, taste, claim threshold, hardening |
| Mouthfeel, carrier | Fats, oils | Oxidation, melting behaviour |
Model cost of goods (COGS) from the start: cost-in-use per kg of finished product = Σ(inclusion fraction × price per kg) ÷ yield fraction. Dividing by yield matters, because a formula that loses 10% of its mass in baking costs about 11% more per kg sold than its raw-material sum suggests. Use supplier quotes and file each supplier specification. For a worked view of mapping functions to ingredients, see how brands map ingredient functionality in NPD.
Gate 2: functions mapped, first bill of materials costed and supplier specifications on file.
Change one factor at a time only when you are confident the factors do not interact. Protein and hydrocolloid levels, or sugar and acid, usually do, so use a design of experiments (DOE). A full factorial tests every combination: k factors at n levels need nk runs, so cost rises quickly with each added factor.[2] A two-level design estimates main effects and interactions (y = b0 + Σbixi + Σbijxixj), and centre points show whether the response is curved. Plackett–Burman designs screen many factors in few runs; central composite and Box–Behnken designs fit curved responses for optimisation, and a central composite design needs F + 2v + nc runs (factorial points, two axial points per factor, and centre points).[2] Randomise the run order, replicate, and block by session so day-to-day drift does not look like a treatment effect.[2]
| Standard order | Protein level | Hydrocolloid level |
|---|---|---|
| 1 | Low | Low |
| 2 | High | Low |
| 3 | Low | High |
| 4 | High | High |
| 5–6 | Mid | Mid (centre points) |
Run the six trials in a randomised order. If the centre points sit well away from the average of the four corners, the response is curved and a central composite design is the next step.
Give every batch a version number, weigh every ingredient, record the process yield and keep an unchanged control in each session. Measure pH and water activity before anyone tastes, so a version that has drifted out of its safety category is rejected on data, not after a panel likes it.
Gate 3: a version that meets the water activity, pH and texture targets in replicated runs, with the control.
Texture profile analysis (TPA) compresses a sample twice, imitating two bites, and reports hardness, cohesiveness, springiness, gumminess, chewiness, adhesiveness and resilience.[4] In the standard definitions, hardness is the peak force of the first compression, cohesiveness is the ratio of the second to the first compression area, and chewiness is hardness × cohesiveness × springiness. Report the probe, compression level and speed with every result, because TPA values are only comparable under the same settings.
The 9-point hedonic scale is the most widely used scale for consumer acceptance testing; in one study, the number of scale categories did not change acceptance scores for attentive assessors, but attentiveness to the task did affect how the scales were used.[5] Panel size follows training: about five to ten trained panellists, 25 semi-trained, and at least 100 untrained consumers.[2] For method choice, see our note on food sensory evaluation.
Set the pass criteria before the panel sits. For the protein bar example below, the example targets are aw ≤ 0.65, day-30 hardness ≤ 2,200 g and a mean hedonic score of at least 7.0. Every trial goes in the iteration log.
| Version | Change | Yield | aw / pH | Hardness day 0 → 30 (g) | Hedonic (1–9) | Decision |
|---|---|---|---|---|---|---|
| v1 | Baseline (control) | 94% | 0.64 / 6.2 | 1,850 → 3,050 | 6.9 | Reject: hardens |
| v2 | Polyol swapped | 93% | 0.63 / 6.2 | 1,820 → 2,400 | 7.2 | Iterate |
| v3 | Hydrocolloid +0.3% | 93% | 0.62 / 6.1 | 1,800 → 2,150 | 7.4 | Pass: meets all targets |
Note how v1 meets the hardness target on day 0 but fails it by day 30: a release-day texture test alone would have passed it.
Gate 4: results meet the specification, or the log names the next change.
Prototype development ends when the product holds its safety, sensory and physical properties across its intended life, not when it tastes right on day 0. Hardening of high-protein bars is a typical failure, and it is a formulation problem as much as a moisture problem. In an accelerated study at 32 °C, bars made with whey protein isolate started at about 3.4 N and reached almost 100 N by day 37, while bars made with partially hydrolysed whey protein stayed at 10–15 N; the authors linked hardening to phase separation between protein and carbohydrate during storage.[6] The decision this supports: if a bar hardens, review the protein and sugar or polyol system before simply adding moisture, which raises water activity.
Plan shelf-life work with end points and a margin. UK food-safety guidance advises storing test product under reasonable worst-case conditions, testing beyond the intended shelf life to show a margin of error, and testing chilled products at around 8 °C rather than assuming a consumer’s fridge stays below 5 °C. It also notes that accelerated shelf-life testing, which raises temperature and humidity to speed deterioration, may suit long-life ambient products better than standard durability studies.[7] In FRL practice, accelerated runs screen versions and real-time runs confirm the claim. Methods, timelines and cost drivers are in our guide to real-time vs accelerated shelf-life testing.
Gate 5: end points, storage conditions and margin agreed before the shelf-life claim is set.
Pre-screen the formula against the target market’s rules before it is frozen, because a late allergen, additive or approval problem forces reformulation.
| Market | Checkpoint | Basis |
|---|---|---|
| India | A non-specified food or food ingredient (one without a standard under the regulations, other than a proprietary food) needs FSSAI’s prior approval before manufacture or import; see our note on approval of non-specified foods | Approval for Non-Specified Food and Food Ingredients Regulations, 2017, reg. 3(1)[8] |
| US | Major food allergens, including sesame, declared on the label; see lessons from undeclared-allergen recalls | FDA allergen labelling Q&A, Edition 5[9] |
| US | Low-acid, acidified or acid food category at pH 4.6 and aw 0.85 | 21 CFR 114.3[3] |
| EU | The 14 allergen groups in Annex II emphasised in the ingredient list | Regulation (EU) No 1169/2011, Article 21 and Annex II[11] |
Then prove the formula on a pilot batch. Scale-up is not arithmetic: mixing, shear and heat transfer change with batch size. In one study of grape products for older adults, pilot-scale hardness rose significantly in one texture grade but fell in the other two, and pH and sugar acidity differed between lab and pilot scale at every grade.[10] Because the direction of change is not predictable, re-run texture, pH and water activity on the pilot batch against the same specification.
Gate 6: pre-screen cleared, and a pilot batch reproduces the targets.
FRL Inside the Lab: choosing a thermal treatment for a cold-pressed juice
Brief: develop a cold-pressed juice prototype and compare thermal treatments for shelf life without losing fresh taste.
Approach: a tropical, citrus and berry blend was standardised for °Brix, titratable acidity and pH, adjusted to 3.5 ± 0.1. Three treatments were compared: LTLT (63 °C, 30 min), HTST (72 °C, 15 s) and UHT (135–140 °C, 2–5 s), with storage at 4 °C and 25 °C and a 15-person hedonic panel on a 9-point scale.
- HTST was preferred: it balanced microbial safety with retention of fresh taste.
- Freshly prepared juice scored 8.3 for appearance, 8.0 for flavour, 7.5 for mouthfeel and 8.0 overall.
- The processed juice was stable for 21–28 days refrigerated with no microbial growth reported; ambient storage was limited to 3–5 days.
Source: FRL Inside the Lab, Cold-Pressed Juice (15 October 2025). The page does not give fruit ratios, microbial counts, the ambient temperature or which treatment each shelf-life figure refers to.
The example maps onto Steps 1, 3, 4 and 5: a fixed pH target at the brief, a structured comparison of three process conditions, a hedonic panel against a 9-point scale, and storage at chilled and ambient conditions. It was a treatment comparison, not a replicated DOE. The 3–5 day ambient limit is the kind of result that should feed back into the brief: it tells the brand that this product needs a cold chain.
Most failures in the food formulation process come from skipped controls, not weak recipes. Common pitfalls (FRL view) and their fixes:
Formulator’s note: write the gate before the trial
A gate set after the data tends to fit the data. Write down the metric, the test method, the threshold and tolerance, the number of replicates, and what you will do on a pass or a fail. For example: “aw ≤ 0.65 on three replicate batches; if not met, change one factor and re-run with the control.” A gate written this way decides the trial, so a near-miss cannot be argued into a pass.
A prototype is ready to move on when it meets a written specification in replicated runs, holds that specification over a stability study with a margin, clears the target market’s rules and reproduces on a pilot batch. Each of the six gates exists to catch one failure early: a moving target, an untested ingredient interaction, a release-day pass that fails at day 30, or a texture shift at scale. Writing the gates before the trials is the cheapest way to avoid rework later.
If you have a product brief and a target market, FRL’s formulation team can run this gated method with you, from specification to pilot batch.
Start with FRL’s new food product development service, add a shelf-life study for the finished prototype, or contact the team to scope the work.
It converts a product brief into a reproducible formula that meets set targets for composition, pH, water activity, texture, sensory quality, cost and shelf life. It runs through specification, ingredient selection, benchtop trials, sensory and analytical evaluation, stability planning, and a regulatory pre-screen with a pilot batch, each closed by a gate.
A recipe lists ingredients and steps. A formulation is a documented, versioned formula with weights, yields, targets and tolerances for pH, water activity, cost and claims, and the test methods that prove them, so it can be reproduced at scale.
Convert the brief into measurable specifications, select ingredients by function, and run benchtop trials using a structured design with controls and replicates.[2] Evaluate each version against the specification, then confirm stability and repeat the key tests on a pilot batch.
A stable prototype keeps its safety, sensory and physical properties throughout its intended shelf life under realistic, worst-case storage. Shelf-life work should run beyond the intended life to show a margin,[7] and should track the failure most likely for the product, such as hardening in high-protein bars.[6]