As we have previously discussed on the blog, it is possible to halt fermentation through freezing (frozen dough) to resume it later after thawing the pieces. However, this technique comes with numerous challenges. On one hand, certain conditions must be modified during processing to minimize cold damage to the yeast, and on the other hand, at the point of sale, the necessary times to finish the product are very long (thawing, fermentation, and baking), requiring different equipment.

Frozen Products

One way to overcome these drawbacks, allowing us to obtain products with a long shelf life and faster service or consumption at the final point, is to freeze the pieces once finished. However, crunchy breads such as baguettes, ciabattas, or Spanish “barras” suffer in this process, leading to a loss of final quality, primarily manifested as crust flaking. Nonetheless, it is worth noting that all products without a crunchy crust can be frozen with minimal quality loss. Therefore, items like sandwich bread, cakes, or donuts can be frozen, despite not being commonly seen in the frozen section. This is because many of these products have a sufficiently long shelf life without freezing, usually achieved through the use of preservatives, among other additives. Frozen shelf space is limited and valuable, and the cost of frozen storage and transportation would increase the selling price of these products. However, frozen donuts and muffins are available in the market. The reason is that these products are sold to hospitality, catering or distribution, which have suitable storage facilities, and they are thawed before being offered for sale, so the end consumer is usually unaware of this practice.

In Spain, frozen gluten-free sandwich bread has also been marketed. The lower turnover of these products required them to have a long shelf life, more challenging to achieve than in similar gluten-containing products. Techniques to increase shelf life reduced the sensory quality and acceptability of these breads, which was already lower than that of wheat-based products. For this reason, some companies decided to market them frozen, minimizing techniques, ingredients, or processes that, although extending shelf life, reduced quality. It is also important to consider that gluten-free products often have higher prices and can absorb a certain additional cost.

Parbaked Breads

However, as mentioned, it is not possible to freeze crunchy bread without a loss of quality. Nevertheless, these problems disappear if we freeze the pieces halfway through baking, so that only a light baking is necessary at the final point of sale. This process can be carried out very similarly to conventional baking, making it easy to adapt. In the first part of baking, the pieces expand, partly due to the action of the yeast, and the dough remains soft and delicate. However, around halfway through baking, two phenomena occur that facilitate freezing. On one hand, the expansion of the pieces ends as the yeast becomes inactive, eliminating concerns about potential cold damage to the yeast, which has already completed its function. On the other hand, starch gelatinization occurs, significantly increasing the consistency of the pieces, making them more robust and easier to handle. From this point, we could stop baking and freeze the pieces, or even keep them in refrigeration or at room temperature.

There is a current trend to prolong the “industrial” baking as much as possible so that the baking times at the point of sale are minimal. However, as we increase the initial baking times, typical problems of freezing finished bread also increase. Therefore, the optimal point to stop initial baking is after the piece completes its expansion and starch gelatinization, and before the crust begins to brown.

In this type of bread, a slight volume drop has been detected during final baking. This can be minimized with slightly shorter fermentation processes (not excessively forced in this process), with stronger flours, and with improvers that provide stability in these stages of the process, such as DATEM emulsifiers.

Refrigerated

Once the baking process is stopped, the pieces can be stored and marketed at room temperature. However, it should be noted that these pieces still have high moisture, high water activity, and therefore a high risk of microbial deterioration. This results in a very short shelf life. To extend it, modified atmospheres and refrigeration can be used, but the latter increases starch retrogradation phenomena, which must also be taken into account. The use of antimicrobial agents, discussed in the blog, is also necessary. CO₂ is known to have a fungicidal effect against molds and inhibits the development of bacteria and yeast. Therefore, the use of modified atmospheres rich in CO₂, with the presence of nitrogen, low oxygen content, and packaging materials with high gas barrier properties, along with refrigeration, can produce parbaked bread with a shelf life of over 30 days.

In addition, these pieces usually experience a certain loss of aromas generated in the first baking, which is not recovered, and they tend to dry out excessively. The pieces, coming out of the oven, have a drier surface than the interior, but over time, part of the moisture from the internal part moves to the exterior to equalize humidities. This leaves the internal part drier than in a conventional baking process, and in the second baking, the moisture that has moved to the external part evaporates. These phenomena are more significant with higher storage temperatures and a higher surface area/volume ratio, or a higher crust percentage compared to crumb. To minimize this problem, higher hydration of the dough, the use of flours with higher protein content and, therefore, more water absorption capacity, or the use of hydrocolloids such as guar gum or pregelatinized starches, which also have a high water absorption capacity, can be used. The latter (gums and pregel starches) greatly minimize moisture transfer but must be incorporated in very small amounts; otherwise, they would significantly modify the final bread. Finally, it should be considered that part of the starch will retrograde, and this retrogradation must be reversed in the final baking, requiring a minimum time.

Frozen

If the product is frozen after the first baking, conservation times increase significantly, exceeding a year, and problems of drying out (though not entirely eliminated), starch retrogradation, and loss of aroma are reduced. However, production, storage, and transportation costs increase. For the freezing process, the same factors mentioned for frozen dough must be considered, and it should be carried out at the lowest possible temperature (around -40ºC) to minimize the size of the formed crystals. The centre of the pieces should reach a temperature between -7 and -10ºC. Subsequently, they should be stored at a low temperature, preferably at -24ºC, without breaking the cold chain at any time (without exceeding -18ºC).

In some of these breads, a slight separation between crumb and crust is observed, along with whitish spots near the crust. The first defect is usually attributed to differences in moisture between both parts and is more common with longer storage times. To minimize it, it is advisable to reduce storage times, not exceed the baking time in the first phase, and use additives with high water retention power, such as hydrocolloids. However, lightly moistening the crust before freezing can also help reduce this problem. The appearance of white spots is due to dryness in that area, having moved from the internal part to the external part of the pieces. They partially disappear in the final baking but may remain in part. To minimize this problem, the mentioned changes to prevent moisture migration should be adopted, along with respecting storage times and maintaining the cold chain.

Although the quality of these breads has been criticized at some point, both nutritionally and organoleptically, it must be noted that this technique hardly modifies the products. Nutritionally, they are very similar to those obtained through the traditional process. It is not true that they contain more additives than most commercial bread, although these additives may be slightly different. Organoleptic quality depends on the production process. They can be of poor quality, based on fast processes that result in low-quality bread, similar to applying them in traditional processing, with less flavour and aroma and quick hardening. However, high-quality bread can also be produced through these processes, based on slow processes, with long fermentation times, very tasty, and aromatic.

Other Products

These techniques also apply to other types of dough, such as pizzas. However, there are products where these techniques cannot be applied. The most well-known example is fermented laminated dough, such as croissants. These pieces, which cannot be frozen once finished due to their crispy nature, also cannot be frozen halfway through baking due to the excessively soft and difficult-to-handle nature of these doughs at that moment. This is related to the high-fat content and the melting of these fats during baking. Therefore, in the case of croissants, frozen dough is usually used. This implies the need for a proofing chamber at the final point. Although this equipment is common in bakeries, it is not as prevalent in some points of sale that only have a small oven. To solve this problem, frozen croissants that do not require proofing have been developed. This statement is somewhat deceptive, as the goal is for fermentation to occur in the early stages of baking. For this, the amount of yeast is increased, and even the use of leavening agents or baking powders can be considered. This way, the volume increase achieved with fermentation can be achieved more quickly at the beginning of baking before the dough reaches the yeast’s inactivation temperature. However, other fermentation characteristics, such as a greater aroma and flavour, and a longer shelf life, would not be achieved. Therefore, these products are suitable for a certain type of consumer but with lower organoleptic quality.

Final Baking of the Pieces

A final aspect to consider is the final baking process. When done correctly, it can maintain the quality of the bread, but if not done properly, it can compromise it. Thus, the pieces cannot go directly from the freezer to the oven and must be thawed beforehand. Otherwise, significant differences between the temperatures of the centre and the exterior occur, resulting in white spots. Additionally, it is crucial to adhere to recommended times and temperatures, and it is not advisable to increase the temperature to speed up the bread or shorten baking times. These issues are very common in the hospitality industry, and catering, where due to poor planning, there is a need for bread in record time.

In Spain, par-baked bread has become prevalent due to its convenience and speed in finishing at the point of sale. However, in other countries like France, frozen dough still has a good market. Some users of this type of dough claim to prefer it for the possibility of distinguishing themselves more from the competition that may acquire similar products.

Today, some companies have chosen to produce fully baked bread that can be frozen at home without a significant loss of quality. They are not promoting it heavily, but consumers are discovering it, and often, they appreciate it. Since the major problem with freezing crispy bread is the flaking due to the dryness of the crusts, we can reduce this issue by slightly reducing the dryness of these crusts and sacrificing some crunchiness. To achieve this, we can use oil in the formulation or employ hydrocolloids. A smaller final volume of the pieces can also facilitate this process. We must reach a balanced solution where we facilitate freezing but do not completely lose the characteristics of these bread types.