Implications of the Mechanical Development of Bread Dough by means of Sheeting Rolls (1974)
Authors: R H Kilborn, K H Tipples

1. Introduction
2. The Authors
3. Hypothesis
4. Evidence base
5. Design and Method
6. Results
7. Interpretation

Introduction

This paper is interesting because it looks at the question of stretching and folding bread vs. kneading it. It does it in a commercial setting which is much more easily controlled and but it can be applied to the home kitchen.

The Authors

Killborn and Tipples wrote a number of papers, including this one, for the Canadian Grain Commission (CGC) in the 1970s & 80s. The CGC is a Canadian state run research institute. This is probably why it is available outside of a paywall. I find it likely that Kiillborn and Tipples are both well qualified research scientists, although I’ve not found specific biographies. The rest of their work appears to be related to grain and the manufacture of bread. I don’t think bias is likely.

Hypothesis

That sheeting rolls are a more efficient method of introducing structure to a dough than commercial mixers. The outcome they look at is energy used to work the dough by these machines.

Evidence base

The study itself references unpublished work of the lab used to find an optimum arrangement for the sheeting rolls. It also acknowledges using a sheeting roll is not a new development, just that it had not been studied in detail before.

Design and Method

Each step is shown in the process. Every variable is controlled including recipe, flour type, temperature and baking method. How the doughs are divided and transferred is not described, there is I suppose a small chance this could introduce variation. How the energy is measured is quite technical, they take the wattage from the machines and adjust for mechanical efficiency in a way I don’t follow. They disregarded the work needed to move the dough to the “top” of the sheeting machine and actually folding the dough.

The outcomes measured are a bit subjective but with the pictures in the figures can be clearly seen.

Results

Mixing and Sheeting can clearly provide the same outcome (similar volume and quality) but with sheeting requires a lot less energy. Mixing (kneading) took 2.8 watt hours per lb of weight (whr/lb) to provide the same result as sheeting with 0.39 whr/lb. 14% of the energy in fact.

If over 20 folds there would be air bubbles trapped in the dough

15-20 Folds with their specific set up was the optimum amount of work for volume and quality.

Interpretation

In my opinion this paper is clearly applicable to the practice of kneading vs repeated stretch and folds in the home kitchen. It is likely to be far more efficient to stretch and fold dough than knead it. This has also been my anecdotal experience.

Is the 15-20 fold ballpark applicable to home baking? Hard to say, it does surely show that overworking a dough as well as underworking a dough is possible even with more gentle methods. Finding that goldilocks zone with home baking might require some trial and error, why not start with 15 folds and see what happens.

Should we be rolling and folding though? In this paper they do not rest the dough in between each fold. When i fail to rest the dough between stretch and folds at home the dough seems to gain too much resistance and often tears, would a roller help?

The appearance of air bubbles after 20 folds is interesting too. Artisanal sourdough tutorials often include many folds in their dough handling steps, often later in the process. Could this be the source of the much sought after “open” crumb? Trapped air bubbles? Interesting to see that commercial bakers see these as serious defects.