Mushroom Taste: How Substrates Make A Difference

Mushrooms are a type of fungus that can be cultivated for consumption. The substrate, or growing material, that mushrooms are grown on can affect their taste. Different substrates provide varying levels of nutrients, moisture, and energy, which can impact the flavour of the mushrooms. Additionally, the type of substrate can influence the yield, nutritional composition, and mineral content of the mushrooms. Some substrates may also introduce contaminants that can affect the taste of the mushrooms. While some people prefer the taste of mushrooms grown on certain substrates, others find that the substrate does not significantly affect the flavour. Further research and experimentation are needed to determine the precise effects of different substrates on mushroom taste.

Mushrooms grown on straw vs. wood

The substrate on which mushrooms are grown can have an impact on their flavour. For instance, king oyster mushrooms grown on straw are said to be blander than those grown on wood. However, some strains of tree oyster mushrooms taste better on straw. Additionally, mushrooms grown in cooler temperatures are said to taste better than those grown in higher temperatures.

Straw is an agricultural waste product from grain crops. It is a good substrate for mushrooms that prefer humid conditions, as it has a high water retention capacity. Wheat straw, oat straw, and rice straw can all be used, and if you live in a subtropical area, sugarcane bagasse can be used as an alternative. It is important to use straw instead of hay because hay contains seed heads that are ripe for contamination and will sprout into weeds.

Sawdust, on the other hand, is a waste product from woodworking and lumber. It is a byproduct of sawing logs into boards. Sawdust is a good substrate for mushrooms that require drier conditions, such as shiitake mushrooms. It is also a good alternative for those who are bothered by the smell of straw, as sawdust does not have a distinct scent.

When it comes to the growth of mushrooms, different substrates can also affect factors such as yield, biological efficiency, nutritional composition, and mineral contents. For example, a study on the effects of different substrates on oyster mushrooms found that increasing corncob and sugarcane bagasse in the substrate formula enhanced the mineral contents of calcium, phosphorus, and magnesium. Additionally, the highest moisture content in oyster mushrooms was obtained from substrates containing 100% sugarcane bagasse or 100% sawdust.

While the substrate can impact the flavour and quality of mushrooms, other factors such as temperature and bacterial contamination can also play a role. For instance, too much nitrogen in a substrate can lead to smelly, off-tasting mushrooms, possibly due to bacterial contamination. Additionally, certain mushroom species may be inherently bitter due to their chemical composition, regardless of the substrate.

The effect of temperature

Temperature is one of the most important factors when it comes to the taste of edible mushrooms. The fruiting temperature affects the taste of the mushrooms, with cooler temperatures generally producing better-tasting mushrooms.

The drying temperature is also significant. Studies on the effects of different hot-air drying (HAD) temperatures on the taste of Suillus granulatus mushrooms found that a temperature of 60°C resulted in a significantly higher equivalent umami concentration, taste activity values of glutamic acid (Glu) and 5'-guanosine monophosphate (5'-GMP), and electronic tongue umami sensory scores. The mushroom-like and sweet odor of S. granulatus was also enhanced when dried at 60°C.

The temperature at which mushrooms are prepared can also influence the taste. For instance, a study on the effect of temperature on flavor compounds and sensory characteristics of Maillard Reaction Products (MRPs) derived from mushroom hydrolysate found that a higher reaction temperature resulted in more nitrogen and sulfur-containing compounds, while alcohols, ketones, and aldehydes were the major flavor compounds obtained at lower temperatures. The study identified an optimal temperature of 125 °C for preparing MRPs with abundant volatile compounds and favorable sensory characteristics, including a higher concentration of free amino acids and 5′-GMP, which are associated with the umami taste.

In summary, temperature plays a crucial role in the taste of mushrooms, impacting both the fruiting, drying, and preparation processes. Cooler fruiting temperatures and a drying temperature of 60°C tend to produce better-tasting mushrooms, while preparation temperatures of 125 °C can enhance the umami taste through the formation of volatile compounds.

Nitrogen content

The substrate used to grow mushrooms can have a significant impact on their taste. While there are many factors at play, one of the most important is the nitrogen content of the substrate. Mushrooms are very sensitive to the amount of nitrogen in their growing medium, and too much or too little can affect their flavour.

Nitrogen is an essential element for the synthesis of protein in mushroom fruiting bodies. The protein content of mushrooms is directly related to the nitrogen content of the substrate they are grown on. The more nitrogen available, the higher the protein content of the mushrooms. However, this can also affect the taste. Mushrooms with a higher protein content may have a stronger or more bitter flavour, which may be desirable for some varieties and less so for others.

A study by Hoa et al. (2015) found that oyster mushrooms grown on 100% sugar bagasse or 100% corncob had higher protein content than those grown on 100% sawdust. Similarly, increasing the amount of corncob and sugarcane bagasse in the substrate formula for two oyster mushroom species (Pleurotus ostreatus and Pleurotus cystidiosus) enhanced their protein content. This was due to the higher nitrogen content of these substrates.

However, it is important to note that too much nitrogen can lead to smelly, off-tasting mushrooms. This may be due to bacterial contamination or other factors that are not yet fully understood. Therefore, finding the optimal nitrogen level is crucial for producing mushrooms with desirable flavours.

In addition to protein content, the nitrogen level in the substrate can also influence other aspects of mushroom growth and quality. For example, the C/N ratio (carbon to nitrogen ratio) affects the overall yield, biological efficiency, and quality of mushrooms. A lower C/N ratio, indicating higher nitrogen content, generally supports better mushroom yield and quality. This relationship was observed in a study by Mintesnot et al., where organic residues with a greater C/N ratio reduced the yield and quality of three oyster mushroom species.

Furthermore, the nitrogen content of the substrate can interact with other factors to influence the taste of mushrooms. For example, the temperature at which mushrooms are fruited can affect their flavour, with cooler temperatures generally producing better-tasting mushrooms. The interaction between nitrogen levels and temperature may be complex, and further research is needed to understand how these factors collectively impact the taste of mushrooms.

Type of tree

The type of tree used as a substrate can indeed influence the taste of mushrooms. Mushrooms absorb the compounds present in their growing environment, which can affect their flavour. For instance, king oyster mushrooms grown on straw are blander than those grown on wood. Similarly, some strains of tree oyster mushrooms taste better when cultivated on straw, while others develop superior flavour profiles when grown on wood.

Furthermore, specific tree varieties may impart distinct flavours to mushrooms. For instance, lion's mane mushrooms grown on a combination of coffee and cocoa bean shells were described as very bitter and inedible, possibly due to the absorption of bitter alkaloids from coffee and cocoa. This suggests that different tree substrates could result in varying flavour profiles in mushrooms.

The choice of tree substrate can also influence the mineral content of mushrooms. For example, a study on oyster mushrooms (Pleurotus ostreatus and Pleurotus cystidiosus) found that increasing the proportion of corncob (CC) and sugarcane bagasse (SB) in the substrate enhanced the mineral content, including calcium, phosphorus, and magnesium. Therefore, the type of tree used as a substrate not only affects the taste but also the nutritional composition of mushrooms.

Additionally, the moisture content of mushrooms can be influenced by the type of tree substrate. Oyster mushroom (Pleurotus cystidiosus) grown on 100% corncob (CC) substrate had the lowest moisture content, possibly due to the poor water-holding capacity of corncob. In contrast, the same mushroom species attained the highest moisture content when grown on sugarcane bagasse (SB) or sawdust (SD) substrates, which have superior water retention properties.

While the type of tree substrate plays a role in mushroom taste and quality, other factors also come into play. For example, the temperature at which mushrooms are fruited can impact their flavour. Mushrooms fruited in cool temperatures tend to taste better than those fruited in high temperatures. Moreover, excessive nitrogen in the substrate can lead to smelly, off-tasting mushrooms, possibly due to bacterial contamination.

Type of straw

Straw is a versatile substrate that can be used by both home-based mushroom growers and commercial mushroom farms. It is the most common substrate for oyster mushroom cultivation. Wheat straw, oat straw, and rice straw can all be used, with wheat and oat straw being the most popular choices in North America. Straw is easy to prepare and provides good nutrition for mushrooms.

To prepare straw for mushroom cultivation, it is recommended to wash the straw with a small amount of dish soap to remove dust and debris. This step also reduces the bacteria on the straw and lowers the risk of contamination. After washing, the straw must be thoroughly rinsed to remove any soap residue. Pasteurization is then carried out to further reduce the chances of contamination. There are two common methods for pasteurizing straw:

• For smaller batches: Place the straw in a pillowcase, nylon mesh laundry bag, or similar container and submerge it in water heated to 160-170 degrees Fahrenheit for about an hour. Drain the straw well, squeezing out any excess water.
• For larger batches: Use a 55-gallon drum, a wire mesh basket, and a butane burner to pasteurize a whole bale of straw outdoors.

After pasteurization, the straw is ready for inoculation with spawn. The wet straw can be spread on a clean surface and inoculated with spawn. This process of exposing wet straw to air destroys anaerobic organisms, resulting in straw that is pasteurized and ready for mushroom growth.

Oyster mushrooms are one of the easiest mushrooms to grow on straw, and they often produce high yields. All oyster mushroom strains will grow on straw, including blue, golden, pink, pearl, phoenix, and king oyster varieties. King oyster mushrooms grown on straw have a bland taste compared to those grown on wood, but they still have a great texture. Additionally, some strains of tree oyster mushrooms taste better when grown on straw.

The type of straw used can influence the mineral content of the mushrooms. For example, increasing the amount of corncob (CC) and sugarcane bagasse (SB) in the substrate formula enhances the mineral content of oyster mushrooms, specifically calcium, phosphorus, and magnesium.

Frequently asked questions