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How to make gravy (using chemistry)

<div class="theconversation-article-body"><a href="https://theconversation.com/profiles/nathan-kilah-599082">Nathan Kilah</a>, <em><a href="https://theconversation.com/institutions/university-of-tasmania-888">University of Tasmania</a></em></p> <p>“Gravy Day” is a relatively new date in the Australian calendar. Paul Kelly’s song <a href="https://theconversation.com/humbug-tinsel-and-gravy-in-search-of-the-perfect-christmas-pop-song-88924">How to Make Gravy</a> tells the story of a prisoner (Joe) writing to his brother on December 21. Joe laments missing the family Christmas celebrations and asks who will make gravy for the roast lunch in his absence.</p> <p>While a roast may not be everyone’s idea of the perfect <a href="https://theconversation.com/a-festive-feast-of-fish-and-fruit-the-creation-of-the-australian-christmas-dinner-151201">Christmas feast</a>, “Gravy Day” does give the opportunity to discuss the chemistry involved in making gravy – a thickened sauce made from drippings collected from roasted meats.</p> <h2>Give my love to Angus (beef?)</h2> <p>Roasting meat sets off a cascade of chemical reactions, producing myriad new flavour chemicals. More than <a href="https://link.springer.com/chapter/10.1007/978-1-4615-2143-3_10#:%7E:text=This%20has%20resulted%20in%20the,and%20lean%20components%20of%20meat.">1,000</a> flavour compounds have been identified in roasted meats.</p> <p>Each chemical gives its unique characteristics to the taste and smell of the finished roast. The chemical <a href="https://www.sciencedirect.com/science/article/pii/S0308814698000764">12-methyltridecanal</a> helps give roast beef its “beefy” flavour, while the sulfur-containing compound <a href="https://www.sciencedirect.com/science/article/pii/S0963996922004422">2-methyl-3-furanthiol</a> is more often found in roast chicken.</p> <p>There are three main types of chemical reactions taking place when roasting meats that produce flavour chemicals.</p> <p>The <a href="https://theconversation.com/kitchen-science-from-sizzling-brisket-to-fresh-baked-bread-the-chemical-reaction-that-makes-our-favourite-foods-taste-so-good-58577">Maillard reaction</a> is responsible for both colour and flavour. This broad reaction type takes place between amino acids from the protein and sugars and simple carbohydrates found in the meat.</p> <p>The Maillard reaction is also the chemistry responsible for many favourite flavours, including roasted coffee, chocolate, steak, toast and more.</p> <h2>A hundred degrees, even more maybe</h2> <p>The other main type of reaction occurring in a hot oven is the breakdown of fats by “<a href="https://doi.org/10.1016/j.foodres.2022.111385">lipid degradation</a>”. This can form hundreds of different chemical compounds. Many of these chemicals are described as “fatty”, “tallowy”, or smell like fried foods.</p> <p>The unique fat profiles found in different animals translate to the profile of flavour chemicals that form from lipid degradation when roasted. Further flavour compounds can arise through the third type of reactions combining products of Maillard reactions and lipid degradation.</p> <p>One specific flavour compound identified as having a “gravy aroma” is known as <a href="https://pubs.acs.org/doi/10.1021/jf9023189">3-mercapto-2-methylpentan-1-ol</a>. This compound comes from roasted vegetables, so including some veggies in your roasting pan will give you more depth of gravy flavour. Also, “cutting onions” is a useful excuse if listening to How to Make Gravy gets you feeling emotional.</p> <h2>The treasure and the trash</h2> <p>Roasting meats causes the fats to “render” and separate from the meat as a liquid. The fat pools in the tray with flavour-rich meat juices.</p> <p>While the fat and the water both carry flavour compounds, too much fat can give the finished gravy an unpleasant mouth feel, or can separate into layers when served.</p> <p>It’s worth pouring off the pan juices into a jug to allow the fat to separate from the liquid so you can control how much fat you’re adding. Be sure to dispose of the excess fat responsibly – <a href="https://theconversation.com/why-shouldnt-i-pour-oil-or-paint-down-the-sink-and-what-should-i-do-instead-206604">don’t pour it down the drain</a>.</p> <h2>Just add flour…</h2> <p>Flour (or, more specifically, starch) is the secret ingredient of a good gravy. Starches are <a href="https://www.sciencedirect.com/science/article/pii/S0168945222000474">large complex chemicals</a> that are made up of lots of sugars joined together.</p> <p>Starch granules are tightly packed and swell greatly when they absorb water. The swollen starch molecules forms a gel-like network that traps water and oil to give a thickened gravy.</p> <p>Wheat flour is most often used as the starch source. Corn and arrowroot starch can also be used. They have a higher percentage of starch than flour and a more neutral flavour.</p> <p>Wheat starch typically requires a larger quantity to be added and longer cooking to form a paste. Whichever starch you use, don’t add it too quickly or without mixing as you’ll form lumps.</p> <h2>…salt, red wine, and a dollop of tomato sauce</h2> <p>Salt is a common ingredient when preparing roast meats, both on the surface of the meat to draw out moisture and as a flavouring agent. The pan juices are typically concentrated as part of the gravy making process.</p> <p>Make sure you taste the gravy before seasoning, as salt will be concentrated by heating.</p> <p>Additional flavour components can be introduced by adding red wine, sherry, stock, or tomato sauce. These ingredients will broaden the flavour profile through sweetness (sugar), acidity (vinegar, citric and malic acids), and umami in the case of tomato sauce (natural glutamates, such as those found in MSG). Some folk even add Vegemite to their gravy for an extra umami boost.</p> <h2>I bet it will taste the same</h2> <p>If you happen to have screwed up your gravy this time, or are after convenience, then you can turn to an instant gravy powder. The main ingredient is typically maltodextrin or another corn-derived (and possibly chemically modified) starch.</p> <p>Shelf-stable powdered fats, salt, colours, and a range of <a href="https://theconversation.com/busting-the-myth-that-all-food-additives-are-bad-a-quick-guide-for-label-readers-82883">flavour additives</a> will be present in varying amounts depending on the style and price point of the product.</p> <p>The advantages of the instant version are speed and uniformity due to the carefully controlled commercial production.</p> <p>So unlike Joe’s concerns for his family’s gravy, an instant gravy will be more likely to taste the same, regardless of who ends up making it.<!-- Below is The Conversation's page counter tag. 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More info: https://theconversation.com/republishing-guidelines --></p> <p><em><a href="https://theconversation.com/profiles/nathan-kilah-599082">Nathan Kilah</a>, Senior Lecturer in Chemistry, <a href="https://theconversation.com/institutions/university-of-tasmania-888">University of Tasmania</a></em></p> <p><em>Image credits: Shutterstock </em></p> <p><em>This article is republished from <a href="https://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/how-to-make-gravy-using-chemistry-219589">original article</a>.</em></p> </div>

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How to make the perfect gravy

<p>Great gravy is the crowning glory of the festive meal.  Rich, brown, smooth and deeply flavoured, it somehow pulls together all the different things on the plate into one celebratory whole.</p> <p>Here are three ways to make gravy that will be loved by everyone at the table.</p> <p><strong>1. THE ULTIMATE GRAVY</strong></p> <p>Classic gravy comes from the classic roast, combining the fat in the roasting pan with flour, to form a roux that is the thickening agent.</p> <p><strong><span style="text-decoration: underline;">Serves:</span></strong> 6</p> <p><strong><span style="text-decoration: underline;">Ingredients:</span></strong></p> <ul> <li>3 tbsp. fat from the roast </li> <li>3 tbsp. plain flour</li> <li>750ml chicken or vegetable stock, heated</li> <li>2 tsp. Vegemite or dark soy sauce (see tips at bottom of article) </li> <li>3 sprigs of fresh thyme</li> <li>Sea salt and pepper</li> </ul> <p><strong><span style="text-decoration: underline;">Method:</span></strong></p> <ul> <li>Pour off all but 3 tbsp. of the fat in the roasting pan and place over low heat. When hot, scatter the flour over the top and stir with a wooden spoon over low heat, scraping up all the meaty bits, for 3 to 4 minutes. The idea is to cook the flour until lightly golden, so it doesn't taste raw.</li> <li>Add the hot stock slowly, stirring quickly to incorporate the flour.  Bring to the boil, then transfer to a saucepan. </li> <li>Add the Vegemite and thyme, whisking well until smooth. Simmer gently for a good 15 minutes.</li> <li>If too thin, continue to simmer and reduce. If too thick, add more stock or the resting juices from the roast. Taste for salt and pepper. </li> <li>Strain the gravy through a sieve, pressing the remains against the mesh with a wooden spoon. Reheat and serve hot.</li> </ul> <p><strong>2. CHEAT'S GRAVY</strong></p> <p>No roast required – which means you can make this quick gravy immediately before serving your feast and it's good to go. You can make a vegetarian version of this gravy by using meat-free stock.</p> <p><strong><span style="text-decoration: underline;">Serves:</span></strong> 4</p> <p><strong><span style="text-decoration: underline;">Ingredients:</span></strong></p> <ul> <li>2 tbsp. butter </li> <li>2 tbsp. plain flour</li> <li>500ml chicken or vegetable stock, heated</li> <li>2 tsp. Vegemite or dark soy sauce </li> <li>3 sprigs of fresh thyme</li> <li>Sea salt and pepper</li> </ul> <p><strong><span style="text-decoration: underline;">Method:</span></strong></p> <ol> <li>Melt the butter in a saucepan. Scatter the flour over the top and stir with a wooden spoon over gentle heat for 3 to 4 minutes. The idea is to cook the flour until lightly golden, so it doesn't taste raw.</li> <li>Start adding the hot stock slowly, stirring quickly to incorporate the flour. Add the Vegemite and thyme and whisk until smooth, then simmer for a good 15 minutes. </li> <li>If too thin, continue to simmer and reduce. If too thick, add more stock.  Taste for salt and pepper.  Strain the gravy through a sieve, and serve hot.</li> </ol> <p><strong>3. GLUTEN-FREE GRAVY</strong></p> <p>Rice flour takes the place of wheat flour, smoked paprika and tamari add depth, and a touch of cornflour gives a smooth, glossy finish.</p> <p><strong><span style="text-decoration: underline;">Makes:</span> </strong>300ml</p> <p><strong><span style="text-decoration: underline;">Ingredients:</span></strong></p> <ul> <li>2 tbsp. butter or fat from the roasting pan</li> <li>2 tbsp. rice flour</li> <li>500ml chicken or vegetable stock, heated</li> <li>2 tsp. tamari (wheat-free soy)</li> <li>Half tsp. smoked paprika</li> <li>3 sprigs of fresh thyme</li> <li>Sea salt and pepper</li> <li>1 tsp. cornflour mixed with 1 tsp butter</li> </ul> <p><strong><span style="text-decoration: underline;">Method:</span></strong></p> <ol> <li>Heat the butter or fat in a pan, and scatter with the rice flour. Cook over low heat for 3 minutes, stirring constantly with a wooden spoon, until lightly tanned. Slowly and carefully (it's hot), start adding the stock, stirring constantly, keeping the mixture at a gentle boil.</li> <li>Add the tamari, smoked paprika, sea salt and pepper, and gently simmer for a good 10 minutes, stirring occasionally.</li> <li>Strain the gravy through a sieve, and reheat. Add the cornflour mixed with butter and bring to the boil, whisking constantly. Simmer for a further minute as the gravy thickens, and serve hot.  </li> </ol> <p><strong>MORE HOT GRAVY-MAKING TIPS</strong></p> <ul> <li>A teaspoon or two of Vegemite or soy sauce adds colour and seasoning.</li> <li>On Christmas Day, roast your turkey with rashers of bacon over the breast to protect it from drying, then toss the roasted bacon into the simmering gravy for extra flavour. Strain before serving.</li> <li>If you're cooking darker, gamier meats, start your gravy off with a glass of red wine. Allow it to bubble and burn off the alcohol, then finish with stock.</li> <li>As a general rule, allow for 1 cup (250 ml) of stock for each tablespoon of flour.</li> <li>Add in anything that will add flavour – rosemary, bay leaves, chicken wing-tips, roasted carrots, garlic, fried onions. Allow to simmer, then strain before serving.</li> <li>Got lumps? Use a whisk or a potato masher, then strain through a sieve before serving</li> </ul> <p>Got a winning gravy recipe of your own? Share it with us in the comments below!</p> <p><em>Written by Jill Dupleix. First appeared on <a href="http://Stuff.co.nz" target="_blank"><strong>Stuff.co.nz.</strong></a></em></p> <p><em><strong>Have you ordered your copy of the Over60 cookbook, The Way Mum Made It, yet? Featuring 178 delicious tried-and-true recipes from you, the Over60 community, and your favourites that have appeared on the Over60 website, <span style="text-decoration: underline;"><a href="https://shop.abc.net.au/products/way-mum-made-it-pbk" target="_blank">head to the abcshop.com.au to order your copy now</a></span>.</strong></em></p> <p><strong>Related links:</strong></p> <p><a href="/lifestyle/food-wine/2016/04/roast-chicken-with-persimmons-and-puy-lentils/"><span style="text-decoration: underline;"><em><strong>Roast chicken with persimmons and puy lentils</strong></em></span></a></p> <p><a href="/lifestyle/food-wine/2015/12/chunky-steak-pie/"><span style="text-decoration: underline;"><em><strong>Chunky steak pie</strong></em></span></a></p> <p><a href="/lifestyle/food-wine/2015/12/diy-barbecue-sauce/"><span style="text-decoration: underline;"><em><strong>DIY barbecue sauce</strong></em></span></a></p>

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