Tomato Shio-Koji: An Ultra-Umami Condiment

Before diving into the tomato umami bomb we’re about to create, it's crucial to understand the foundational ingredient: shio-koji. Shio-koji, at its simplest, is a fermented mixture of koji rice (rice inoculated with Aspergillus oryzae), water, and salt. The magic lies in the koji’s enzymatic activity. These enzymes, notably amylase and protease, break down complex carbohydrates and proteins into simpler sugars and amino acids, respectively. This process unlocks an incredible depth of flavor – a concentrated savory note, or umami – that elevates anything it touches. You can learn more about how that process works in Enzyme Biochemistry: How Amylase and Protease Create Flavor.

Think of shio-koji as a living marinade and tenderizer. It not only imparts flavor but also modifies the texture of food. In our tomato shio-koji, this enzymatic activity will work on the tomato pulp, resulting in a complex, savory, and intensely flavored fermented sauce. The salt content acts as a preservative, inhibiting undesirable microbial growth while allowing the koji to work its magic. While fermentation can be a complex and sometimes intimidating process, don't forget to prioritize Safety First: How to Distinguish Koji from Toxic Mold Species. Learning this will help you keep your sauces safe and delicious.

Before we dive into the juicy details of transforming ordinary tomatoes into an umami bomb with shio-koji, let's understand the foundation of this fermented sauce: shio-koji itself. Shio-koji, literally "salt-koji," is a simple yet incredibly versatile Japanese seasoning made from just three ingredients: koji rice (Aspergillus oryzae inoculated rice), salt, and water.

But don't let its simplicity fool you. Koji rice is the secret ingredient; it’s responsible for the enzymatic activity that unlocks a symphony of flavors. The Aspergillus oryzae mold produces enzymes, primarily amylase and protease, that break down starches into sugars and proteins into amino acids. This process isn't just about sweetness; it's about creating the savory depth that we call umami. Think of it as a natural flavor enhancer, capable of transforming even the humblest ingredients into culinary masterpieces. If you're curious about the science, consider reading up on Enzyme Biochemistry: How Amylase and Protease Create Flavor.

Shio-koji is traditionally used as a marinade for meats and fish, a seasoning for vegetables, and even a tenderizer. We're taking that concept and applying it to tomatoes, creating a living sauce that boasts both the bright acidity of fresh tomatoes and the complex, savory depth of fermentation. This is a delicious, innovative take, but keep in mind that good Koji requires good technique. If you're unfamiliar with growing the culture yourself, take a look at Safety First: How to Distinguish Koji from Toxic Mold Species before beginning.

Ready to unlock an umami bomb hiding within your summer tomato harvest? This recipe transforms simple tomato pulp into a complex, flavorful, fermented sauce using the magic of koji rice. This isn't your average tomato sauce; it's a living condiment teeming with enzymatic activity, adding a depth of savory flavor unlike anything you've tasted. We're talking next-level Bloody Marys, elevated pasta sauces, and transformative marinades.

At its core, this recipe combines the sweetness and acidity of tomato with the power of koji, a rice inoculated with Aspergillus oryzae. This beneficial mold, when properly cultivated, releases powerful enzymes that break down starches and proteins into simpler sugars and amino acids – the building blocks of deliciousness. If you’re new to koji, it's important to understand the key differences between beneficial koji and potentially harmful molds; review Safety First: How to Distinguish Koji from Toxic Mold Species before starting.

While the process takes a few days, the active hands-on time is minimal. The reward is a vibrant, versatile, fermented sauce that enhances nearly any dish. We'll walk you through each step, from selecting the right tomatoes to achieving the perfect koji inoculation and fermentation. Get ready to transform your kitchen into a miniature fermentation lab!

Before diving into the specifics of transforming tomato pulp into an umami bomb, let's cover some fundamental principles of koji fermentation. Think of koji rice as a microscopic flavor factory. Aspergillus oryzae, the fungus we cultivate, produces enzymes like amylase and protease. These enzymes break down complex carbohydrates (starch) and proteins into simpler sugars and amino acids – the building blocks of flavor and key to building a delicious fermented sauce.

This enzymatic activity is the heart of the process. In our tomato shio-koji, these enzymes will work on the natural sugars and proteins present in the tomatoes, releasing their hidden depths. The umami you'll experience is largely due to glutamic acid, an amino acid unlocked by protease. This is the same compound that makes aged parmesan cheese so addictive!

Crucially, remember that koji cultivation is temperature and humidity sensitive. Maintaining optimal conditions is critical for success. For instance, Stage 20–36 Hours: Managing Metabolic Heat (Kiri-kaeshi) is a critical point where careful monitoring prevents overheating and unwanted microbial growth. We'll be applying these same basic principles when we are fermenting the tomato pulp.

And finally, while we'll be focusing on tomato, it's worth remembering that shio-koji (salt koji) is an incredibly versatile ingredient. Understanding this foundational recipe will unlock a world of potential fermented creations beyond just tomatoes.

So, why embark on the journey of making tomato shio-koji? The answer is simple: it's an umami bomb unlike anything you've ever tasted. Forget ketchup or even the most intensely sun-dried tomatoes. This fermented sauce takes the inherent savoriness of tomatoes to a completely new dimension.

Think of it as a living flavor enhancer. The magic lies in the koji (Aspergillus oryzae), a mold revered in Japanese cuisine for its enzymatic power. Koji doesn't just sit there; it actively transforms the tomato pulp. The enzymes break down complex carbohydrates and proteins into simpler sugars and amino acids. As a result, the sweetness is amplified, and the glutamates – the key components behind that "umami" sensation – are dramatically increased. Umami: The Scientific Reason Koji Makes Food Taste Better

But the benefits extend beyond mere taste. The fermentation process also creates a wealth of beneficial enzymes and potentially probiotics (though further research is needed on this specific preparation). Plus, it allows you to utilize even imperfect tomatoes – those slightly bruised or overripe specimens that might otherwise go to waste. Just be sure to discard anything with visible mold beyond the desired *Aspergillus oryzae* growth. See Safety First: How to Distinguish Koji from Toxic Mold Species for guidance.

Ultimately, tomato shio-koji is about unlocking the full potential of the humble tomato and crafting a truly unique and versatile condiment. Use it as a base for pasta sauces, a marinade for meats, or even a secret ingredient in your next batch of chili. The possibilities are truly endless!

Why tomato? Beyond their inherent sweetness and acidity, tomatoes harbor a secret weapon: glutamic acid. This naturally occurring amino acid is a primary driver of umami, the savory "fifth taste" that elevates flavors and creates a deeply satisfying culinary experience. Think of it as the foundation upon which we're building this fermented sauce, the initial spark for an umami bomb.

The beauty of fermentation with Aspergillus oryzae (koji) is its ability to unlock and amplify existing umami compounds. Koji contains enzymes that break down complex proteins into simpler amino acids, including even more glutamic acid. By applying this process to tomatoes, we're essentially supercharging their natural flavor profile. Think of a sun-dried tomato—its concentrated flavor is due, in part, to dehydration intensifying the existing glutamates. We're taking that concept a step further through enzymatic action. The resulting fermented sauce is far more than the sum of its parts.

Furthermore, different varieties of tomatoes will yield slightly different results. Experimenting with heirloom varieties, like those with dense flesh and low water content, can lead to a more intense flavor profile. Remember to always prioritize food safety and be able to identify unwanted mold growth. Safety First: How to Distinguish Koji from Toxic Mold Species

Let's transform ripe tomatoes into an umami bomb using the magic of Aspergillus oryzae! Here's a step-by-step guide to creating your own Tomato Shio-Koji:

1. Prepare the Koji Rice: This process starts with inoculated rice. If you're new to this, consider reading up on Soaking Secrets: How to Achieve 30% Hydration and Steaming vs. Boiling: Why a Traditional Steamer is Essential. A traditional steamer is key for even cooking and preventing a gummy texture that hinders koji growth.
2. Tomato Prep: Roughly chop 1 kg of ripe, flavorful tomatoes (any variety works, but heirlooms offer depth). Remove any tough cores, but the skins are fine. Blitz the tomatoes in a food processor or blender until you have a coarse pulp.
3. Combine Ingredients: In a clean bowl (sterilize it for best results), gently mix the tomato pulp with 200g of your koji rice. Add 30g of salt (sea salt or kosher salt are good choices). Ensure everything is evenly distributed.
4. Fermentation Vessel: Transfer the mixture to a sterilized glass jar or container. Leave some headspace at the top. Lightly weigh down the tomato-koji mixture to keep it submerged (a ziplock bag filled with brine works well). This helps prevent unwanted surface molds. Remember Safety First: How to Distinguish Koji from Toxic Mold Species.
5. Fermentation: Cover the jar with cheesecloth secured with a rubber band, or use an airlock system. Ferment at room temperature (ideally 70-75°F / 21-24°C) for 5-7 days. Stir the mixture daily, pushing down any floating solids. You'll notice the mixture becoming more liquid and aromatic as the enzymes break down the starches and proteins.
6. Taste and Adjust: After 5-7 days, taste the shio-koji. It should have a pleasantly savory, slightly sweet, and deeply umami flavor. If desired, you can blend the sauce for a smoother consistency. Store in the refrigerator; it will continue to ferment slowly.

Ready to transform simple tomato pulp into an umami bomb? This fermented sauce is surprisingly simple, but meticulousness is key to a successful koji fermentation. Here's how:

1. Prepare the Koji Rice: This is the foundation of your tomato shio-koji. Start with about 200g of short-grain rice. The steaming process is critical; do not boil the rice. We're aiming for an "al dente" texture – firm on the outside, soft inside. Why? This encourages the koji fungus to dig deep for moisture, boosting enzyme production. Think of it like this: if the rice is too mushy, the fungus has no reason to work hard, and you risk surface matting. This "Al Dente" Rule ensures maximum flavor potential.
2. Inoculate the Rice: Once the rice has cooled to around 95°F (35°C), gently mix in about 5g of your chosen koji-kin spores. A good quality yellow koji-kin provides a classic, balanced flavor profile. Consider researching Koji-kin: A Detailed Guide to Strains (Yellow, White, Black) to find the variety best suited to your taste.
3. Ferment the Koji Rice: Maintain a consistent temperature of 86-95°F (30-35°C) and high humidity (70-80%) for 48-72 hours. A fermentation chamber, or even a carefully controlled oven, will be helpful here. See DIY: Building a Fermentation Chamber from an Old Refrigerator for tips. Check regularly to ensure proper growth. The rice should be covered in a fluffy, white mycelium.
4. Combine with Tomato: Blend or process approximately 500g of ripe tomatoes into a smooth pulp. Gently mix the fermented koji rice with the tomato pulp. Add a pinch of sea salt (around 1-2% of the total weight).
5. Ferment the Tomato Mixture: Transfer the mixture to a clean jar or container. Leave about an inch of headspace. Allow to ferment at room temperature (68-77°F or 20-25°C) for 5-7 days, stirring daily. Taste regularly to monitor the development of flavor. It should become increasingly complex and savory.

Ready to unleash a fermented umami bomb? This recipe uses the natural enzymes in koji to transform humble tomato pulp into a complex, savory condiment.

Ingredients:

• 1 kg ripe tomatoes, any variety. Roma and San Marzano work beautifully.
• 100g dried Aspergillus oryzae koji rice (approximately 10% of the tomato weight).
• 20g sea salt (approximately 2% of the tomato weight).
• Optional: 1 clove garlic, minced.

Procedure:

1. Prepare the tomatoes: Wash and core the tomatoes. Roughly chop them and then blend them into a pulp. You can use a food processor or an immersion blender. We want a smooth consistency.
2. Combine ingredients: In a sanitized bowl, thoroughly mix the tomato pulp, koji rice, and salt. Ensure the koji is evenly distributed throughout the tomato mixture. The salt is crucial for inhibiting unwanted bacteria, as well as controlling the enzymatic activity that produces the final flavor profile. See Temperature Pauses: 'Programming' Koji for Sweetness vs. Salt for more detail on salt concentrations.
3. Fermentation: Transfer the mixture to a clean glass jar or container. Cover loosely with a lid or cheesecloth secured with a rubber band. This allows gases to escape.
4. Incubate: Ferment at room temperature (ideally 25-30°C or 77-86°F) for 5-7 days. Stir the mixture daily to prevent mold growth and encourage even fermentation.
5. Taste and adjust: After 5 days, taste the fermented sauce. It should have a noticeable tang and a depth of flavor. If desired, ferment for a day or two longer for a more intense flavor. Pay careful attention to any off smells as you do this. See Safety First: How to Distinguish Koji from Toxic Mold Species.
6. Blend (optional): For a smoother consistency, blend the finished tomato shio-koji.
7. Store: Store in the refrigerator. The flavor will continue to develop over time. Use within 2-3 months.

The fermentation process is where the magic happens, transforming your humble tomato pulp into an umami bomb. After mixing the tomato with the koji rice and salt, transfer the mixture to a clean, airtight glass jar, leaving about an inch of headspace.

The ideal fermentation temperature for this fermented sauce is between 80-85°F (27-29°C). This range encourages the koji to thrive. Consistency is key; monitor the temperature closely. An accurate thermometer is essential, and you might consider using a dedicated fermentation chamber, especially if your ambient temperature fluctuates. DIY: Building a Fermentation Chamber from an Old Refrigerator is a great way to maintain a stable environment.

During the first 24-48 hours, you may observe increased activity. This is the koji releasing enzymes like amylase and protease, breaking down the tomato’s complex carbohydrates and proteins. These enzymes release free amino acids like glutamate, directly contributing to the umami. Enzyme Biochemistry: How Amylase and Protease Create Flavor can give you a much deeper understanding of the process.

Stir the mixture daily. This helps to aerate the ferment and distribute the koji evenly. After about 5-7 days, taste the tomato shio-koji. The flavor should be savory, complex, and intensely umami-rich. The texture will also change, becoming softer and almost creamy. If it's not quite there, let it continue to ferment for another day or two, tasting it daily until the desired flavor is achieved.

Once the flavor is to your liking, transfer the shio-koji to the refrigerator. Refrigeration will slow down the fermentation process significantly, preserving the flavor and preventing it from becoming overly sour.

Successful fermentation of your tomato shio-koji hinges on precise temperature control. Koji, like any living culture, thrives within a specific range, and deviating too far can lead to undesirable results – or even complete failure. For this recipe, we're aiming for a sweet spot between 80-88°F (26-31°C) for optimal enzymatic activity and flavor development.

Here's the tricky part: After about 24 hours, the koji starts generating significant metabolic heat as it digests the tomato substrate. This can lead to what's known as "thermal runaway," where the temperature spirals upwards. Research shows that koji can easily drive the tomato mass above 113°F (45°C), at which point the culture begins to die off, halting fermentation and potentially leading to off-flavors. This is one of the main reasons why some batches turn into an umami bomb, while others are simply *blah*.

To counteract this, you'll need a way to regulate the temperature. A dedicated fermentation chamber is ideal. Many professional (and home) fermenters utilize an Inkbird temperature controller with the probe inserted directly into the tomato pulp. This allows the controller to activate cooling mechanisms, such as a small fan, when the temperature exceeds your target. If you're interested in building your own, check out DIY: Building a Fermentation Chamber from an Old Refrigerator. You may also be interested in Setting Up Inkbird Controllers for Koji Cycles.

Keep the tomato-koji mixture fermenting for 5-7 days, monitoring the temperature daily. You'll notice a gradual increase in aroma and a softening of the tomato pulp. The fermentation is complete when the mixture has a pleasantly funky, slightly sweet, and intensely savory aroma.

Achieving a truly exceptional tomato shio-koji requires attention to detail beyond the basic recipe. Think of it as crafting an umami bomb, where even small improvements compound into a more complex and delicious fermented sauce. Here are a few best practices:

• Tomato Selection is Key: Use ripe, flavorful tomatoes. Roma or San Marzano varieties, known for their meaty texture and lower water content, tend to yield a thicker, more concentrated end product. Avoid bland, watery tomatoes.
• Salt Levels Matter: While the recipe provides a guideline, taste and adjust the salt after the initial fermentation phase (around day 3). The salt not only controls microbial activity but also influences the final flavor profile.
• Temperature Consistency: Inconsistent temperatures can lead to off-flavors or inconsistent fermentation. Use a reliable incubator, such as one controlled with an Inkbird, and consider Setting Up Inkbird Controllers for Koji Cycles for optimal control.
• Watch for Pichia: This yeast can sometimes appear as a white film on the surface. While generally harmless, it can contribute a slightly bitter flavor. Skimming it off early in the fermentation can help.
• Mastering the Koji: Using homemade *Aspergillus oryzae* koji is preferable, allowing you complete control over the strain and quality. Pay attention to your koji, observing metabolic heat and perhaps implementing Stage 20–36 Hours: Managing Metabolic Heat (Kiri-kaeshi)

By focusing on these details, you'll significantly elevate the quality and complexity of your tomato shio-koji, creating a truly unforgettable condiment.

Tomato Shio-Koji is more than just a sauce; it's an umami bomb ready to elevate your cooking. Think of it as a fermented, intensely flavored tomato paste with probiotic benefits. Its complex flavor profile unlocks new dimensions in familiar dishes.

Here are just a few creative ways to use your homemade tomato shio-koji:

• Pasta Sauce Booster: Stir a tablespoon into your favorite marinara to deepen the flavor and add a subtle sweetness.
• Meat Marinade: Marinate chicken, pork, or beef for at least 30 minutes (longer is better!). The enzymes in the koji will tenderize the meat while infusing it with that characteristic fermented depth. Remember that Enzyme Biochemistry: How Amylase and Protease Create Flavor can dramatically affect taste and texture.
• Soup Base: Add a spoonful to soups and stews as a base for instant depth. It works especially well in tomato soup, vegetable broth, and even miso soup for a surprisingly delicious twist.
• Pizza Sauce: Use it straight as a pizza sauce for a more complex flavor than traditional tomato paste.
• Bloody Mary Mix: A teaspoon or two adds an incredible layer of umami to your Bloody Mary.
• Dip Enhancement: Mix it into hummus, guacamole, or other dips to boost their savory appeal.
• Compound Butter: Blend with softened butter and herbs for a flavorful compound butter to top grilled meats or vegetables.

Experiment! Once you taste the magic of this fermented sauce, you'll find endless ways to incorporate its rich tomato and koji-derived flavors into your cooking. The naturally-occurring glutamates, a key component of umami, will transform even the simplest dishes.

Tomato shio-koji is relatively forgiving, but problems can arise. Understanding the underlying fermentation process helps immensely. If your shio-koji is too thick, it might be due to insufficient moisture. Next time, try adding a tablespoon or two more of the tomato pulp. Conversely, if it's too thin, you may have added too much water from overly juicy tomatoes. Consider using a thicker tomato paste as a base.

Occasionally, you might notice an ammonia smell. This indicates protein breakdown going too far, often because the fermentation temperature was too high or it was left for too long. Lower your fermentation temperature and check it more frequently. See Troubleshooting: Why Koji Becomes Sticky or Smells of Ammonia for more help.

For enhanced flavor, experiment with different fermentation times. A shorter fermentation (3-5 days) will yield a brighter, more acidic profile, while a longer fermentation (7-10 days) will produce a deeper, more savory flavor – an absolute umami bomb! Remember that enzyme activity dictates flavor development, and you can gently influence that process by adjusting time and temperature. You may find that, just like with miso, aging your fermented sauce for a month or more in the refrigerator after the initial fermentation period really unlocks deeper flavor complexity.

Finally, to coax out even *more* umami, consider adding a small amount of glutamic acid-rich ingredient like kombu or dried shiitake mushrooms to the initial mix. These additions provide an extra boost for the koji enzymes to work on.

Tomato shio-koji is deceptively simple to make, but a few common pitfalls can prevent you from achieving that umami bomb you're craving. Here's what to watch out for:

• Insufficient Moisture: Koji needs moisture to thrive. If your tomato pulp is too dry, the koji won't properly inoculate. You'll end up with mold issues or simply a bland, unfermented mixture. Ensure your tomato pulp is juicy enough, or add a small amount of filtered water to achieve a slightly soupy consistency. Related to this, Humidity Management: Ultrasonic Humidifiers vs. Wet Cloth will be essential for the early stages.
• Incorrect Temperature: Koji has a narrow temperature range for optimal growth. Too cold, and it won't activate. Too hot, and you risk killing the culture. Invest in a reliable temperature controller like an Inkbird to maintain a consistent environment, or monitor the heat closely. If the temperature rises too high during Stage 20-36 hours you may want to consider Stage 20–36 Hours: Managing Metabolic Heat (Kiri-kaeshi).
• Using the Wrong Salt: Iodized salt can inhibit the growth of koji. Always use non-iodized sea salt or kosher salt.
• Impatience: Fermentation takes time. Don't be tempted to cut the process short. A full fermentation cycle is essential for developing the complex flavors of your tomato shio-koji. This allows the enzyme biochemistry of Koji to take full effect.
• Poor Sanitation: Introducing unwanted bacteria or mold can ruin your batch. Always use sterilized equipment and maintain a clean workspace. And if in doubt, familiarize yourself with Safety First: How to Distinguish Koji from Toxic Mold Species.

So, there you have it: your own homemade tomato shio-koji. It might seem a little intimidating at first, but the payoff is immense. You've created a living, breathing condiment teeming with enzymes and microbial activity, a true umami bomb. This isn't just another sauce; it's a testament to the power of fermentation.

Experiment! Use it as a marinade for chicken, a secret ingredient in your pasta sauce, or a flavor enhancer for grilled vegetables. Don't be afraid to adjust the fermentation time based on your own taste preferences. Remember that longer fermentation equals a more intense flavor. Keep detailed notes so you remember which parameters worked best, particularly if you modified the humidity or temperatures described in Setting Up Inkbird Controllers for Koji Cycles.

Beyond the deliciousness, you've also unlocked a deeper understanding of food and the amazing processes that shape its flavor. Consider further study of Enzyme Biochemistry: How Amylase and Protease Create Flavor to expand your knowledge on this fascinating process. This fermented sauce is a springboard to more complex culinary adventures. Enjoy!

Tomato shio-koji is more than just a condiment; it's an umami bomb ready to explode with flavor in your favorite dishes. The fermentation process unlocks the natural sweetness of the tomato and deepens its savory profile, making it incredibly versatile.

Here are some culinary applications to get you started:

• Marinades: Use tomato shio-koji as a marinade for chicken, fish, or tofu. The enzymes break down proteins, resulting in incredibly tender and flavorful results. A small amount goes a long way!
• Sauces: Add a spoonful to pasta sauces, stews, or soups for an instant boost of umami. Consider experimenting with different amounts based on your preference for a more or less intense flavor.
• Dressings: Whisk it into vinaigrettes or creamy dressings for salads and slaws. The subtle acidity balances the richness of oils and adds a complex savory note.
• Dips: Blend it with cream cheese, yogurt, or avocado for a unique and flavorful dip for vegetables or chips.
• Flavor Enhancer: Use it as a finishing touch to grilled vegetables, roasted meats, or even scrambled eggs. A small dab can elevate a simple dish to something extraordinary.

Don't be afraid to experiment! Think of it as a fermented tomato concentrate, packed with flavor and ready to transform your cooking. If you're looking for tips to manage the humidity level in your fermentation, check out Humidity Management: Ultrasonic Humidifiers vs. Wet Cloth.

Tomato shio-koji is a surprisingly adaptable condiment. Don't be afraid to experiment! Once you've mastered the basic recipe, consider these variations:

• Spice It Up: Add a pinch of chili flakes, a finely minced jalapeño (seeds removed!), or a dash of your favorite hot sauce to the tomato pulp before mixing with the koji. Start small; you can always add more heat later.
• Herb Infusion: Fresh herbs, finely chopped, can add another layer of complexity. Basil, oregano, or even a bit of rosemary can work well with tomato. Remember that rosemary can be overpowering, so use it sparingly.
• Sweetness Adjustment: If your tomato shio-koji is too salty for your taste, try a temperature pause during the koji fermentation process to encourage the saccharification of starches into sugars. Temperature Pauses: 'Programming' Koji for Sweetness vs. Salt
• Garlic Boost: Roasted garlic is a fantastic addition. Roast a head of garlic until soft, then mash a few cloves into the tomato pulp. Raw garlic is also an option, but its pungency will be more pronounced.
• Experiment with Koji Strains: Different koji-kin will produce different flavor profiles. Koji-kin: A Detailed Guide to Strains (Yellow, White, Black) Yellow koji is commonly used, but white koji might yield a slightly milder, fruitier result. Black koji might offer a more complex, funky umami flavor, but be cautious as its strong proteolytic activity can lead to overly intense flavors if not monitored.

Important Tip: Always taste your tomato shio-koji as it ferments. This allows you to adjust seasonings and catch any off-flavors early. And remember, safety first! If you see any signs of mold that aren't fluffy and white, err on the side of caution and discard the batch. Safety First: How to Distinguish Koji from Toxic Mold Species