Cold Brew And Hot Brew: While we know that water temperature can alter the extraction of aromatics, caffeine concentration, total solids content, antioxidants, etc., the hot extraction process has been thoroughly investigated.
Physico-chemical and sensory aspects of several hot extraction procedures have been compared in research. In contrast, few scientific investigations on its physicochemical and organoleptic qualities have been published despite the growing popularity and interest in cold coffee.
Cold brew coffee’s physical, chemical, and sensory qualities versus hot (conventional) coffee are influenced by temperature and grain size.
This is one of the first systematic differences between cold brew and standard brewing methods.
Cold brew coffee and various methods of extraction
Various technologies have been devised to extract coffee, the majority of which involve high-temperature (near-boiling) water and a short extraction time (no more than 5 minutes).
However, in recent years, various innovative approaches have gained popularity on the market, and cold brew is also known as cold brewing.
Still, the extraction method is done at room temperature (20 to 25°C or more challenging) for a longer time than the traditional hot extraction method, for a longer time than the conventional hot extraction method, for (typically 8 to 24 hours).
A coffee-based beverage with different organoleptic and physicochemical qualities results from low temperatures and prolonged exposure. These variables impact the rate of extraction and how the flavor components in the coffee interact with the water.
Because the chemical elements in coffee have diverse chemical properties (such as polarity and solubility), their dissolution kinetics differ. In general, higher temperatures increase solubility and impact flavoring compound saturation vapor pressure.
Basics difference between hot brewed coffee and cold brewed coffee:
- Cold brewing coffee: cold brewing leaves behind some acids that hot coffee pulls out easily.
- Hot brew coffee: hot brewing extracts more antioxidants from the grind than cold brew, hot brew has a more acidic, great hot brewed coffee has a rounded flavor.
Cold brew and hot brew extract physicochemical properties.
According to coffee makers and connoisseurs, cold-brew and hot coffee from the same coffee have different flavor profiles. The physicochemical features of cold coffee account for this variation.
The physicochemical properties of cold-extracted coffee are most affected by the size of the beans after grinding, followed by the extraction time. The extraction yield (EY) and total dissolved solids (TDS) in cold brew were increased by coarse grinding and long extraction durations. Both fineness and extraction time affect the entire phenolic content (TPC) of cold coffee at the same time.
The powerful polyphenols in coffee are chlorogenic acid and related compounds, which account for 7-9 percent of the dry mass (depending on the type of coffee).
Overall, coffee polyphenols are highly bioavailable and have solid antioxidant capabilities, making them suitable for human health (according to coffee and health).
Size, timing, and temperature brewing of the particles
The grinds are placed in a filter bag for cold coffee, then placed in a water tank for a prolonged extraction time. This “packing” effect during the extraction process may have lowered the diffusivity, lowered the soluble solids (TDS) content, and lowered the coffee extraction rate (EY).
The primary criteria impacting the permeability and diffusion of solids during cold coffee extraction, according to recent studies, are particle size, particle homogeneity, and filter shape.
On the other hand, even when utilizing the coarse grind method, the extended Extraction Time used in cold extraction tended to raise the values of TDS, EY, and TPC. Water temperature can be considered the driving force behind the extraction of chemical components present in coffee powder during the preparation process.
However, because the temperature is low (below room temperature) during cold brewing, some chemicals require more time to extract and diffuse to compensate for the low temperature.
This could explain why EY and TDS are still present in a cold brew with a more extended extraction period.
Acidity in total
The titratable acidity value (TA) is measured in milligrams of chlorogenic acid and measures the acidity induced by all organic acids found in coffee.
In addition to the grinding procedure, the type of coffee has a significant impact on pH and total acidity (TA). There have been numerous investigations on cold extraction with coffee from various nations.
It was also shown that while both cold and hot-brewed had similar total acid components, their concentrations were different (cold coffee had lower concentrations).
Several acids have been found in coffee, including acetic, formic, malic, lactic, phosphoric acids, and quinic and chlorogenic acids. Because their solubility increases with temperature, some of these acids may be extracted very efficiently in the initial seconds of hot extraction, which is why brewed hot have such a high value.
The TA of hot coffee brewing is higher than that of cold coffee. All burdensome extraction procedures, on average, have lower acidity values than hot extractions.
However, various studies have found that seeds’ pH and total acidity (TA) are affected by multiple factors, including species, geographical origin, fruit maturity, harvest method, etc. planning, processing techniques, and all post-harvest processing processes, etc.
Furthermore, the degree of roasting and the exact preparation procedure impact pH and acidity.
Coffee flavor profile in hot brewed coffee and cold brewed coffee
The testing results demonstrate substantial differences in taste, aroma, aftertaste, acidity, and intensity of hot extracts compared to all cold extraction techniques in terms of flavor attributes.
On the other hand, cold-extracted coffee had a flavor profile similar to that of hot-extracted coffee.
As a result, the reviewers discovered that, while some flavor qualities in the cold brew are “poorer” than in hot brews beverages, the flavor of cold medicine may be acceptable in general. It’s okay for coffee drinks.
- More specifically, some of the flavor characteristics of cold brew can be summarized as follows:
The flavor profile of cold coffees (iced coffee) is characterized by a malt flavor, which is distinct from the flavor profile of hot brewed coffee extracts. Other flavor qualities such as almonds, flowers, red fruit, and bitterness are also high marks in cold coffee.
By flavor profile, cold coffee brewed for 18 hours was the most agreeable to customers throughout the study range. The aftertaste qualities of coffee brewed for 14 hours were all lower than those of samples produced using the hot brew method.
Cold coffee, in general, can have a higher intensity of sugar caramels, sweetness, and bitterness while yet maintaining balance and a smooth body.
Is it true that cold brew is preferable?
Many elements influence each preparation process, and we assess quality based on various criteria. A general comparison of cold brew to regular coffee would be ridiculous.
Coffee is both scientific and aesthetic. A coffee bean’s molecular science and the barista’s craftsmanship are inextricably linked. As a result, while some people who prefer hot coffee may switch to cold brew owing to brewing technique, others may discover the actual taste of a Specialty Coffee that is meticulously extracted with hot water after trying cold brew. After all, coffee has its style of influencing a “follower,” which we term “gu”/.