White Coffee is generally a light-roast coffee that a few coffee shops have started to sell. The consensus seems to be that it is simply a very under-roasted coffee bean. The advertising hype that goes with it would agree with this assumption, although the people selling this product will not say anything about how it is made.
White Coffee is actually fairly difficult to roast properly, given that roasting imparts many of the flavor changes most people associate with what a "coffee" is.
White Roast vs. Light Roast
Light roasts retain many of the prominent single origin coffee bean flavors, along with more of the plant-based chemicals and organic acids that aren't the most pleasant tasting. These nuances however, are what are used to identify the best coffee beans when quality graders do their coffee cupping. This higher volume of organic acids and other compounds is exactly what purportedly makes it healthier however, and is impacted to a great extent by the severity of the roast.
Unfortunately there's no consensus on what a white coffee really is - companies that produce their private branded coffee obscure the origin as well as roast level intentionally to create consumer lock-in. While a company may simply be selling a low-priced coffee, the lack of transparency means that they can price it as high as they want. There's also no real evidence that white coffee is substantially healthier than a regular, light-medium roasted coffee, or coffee in general.
Those who have tried it typically describe it as having nutty, almost grass-like flavor, which adequately describes the first early stages of coffee roasting.
Is a "White Coffee" actually white?
While it will be a lighter brown color than most darker roasted coffees, it will not actually be white.
White Coffee Caffeine Content
One of the common claims about white coffee is that it is higher in caffeine than normal coffee. In theory, coffee loses caffeine by volume as it is roasted so it probably does have more caffeine by volume.
This point is negligible compared to the differences between different origins - a high grown Ethiopian coffee bean for example would have more caffeine than a low-altitude Brazilian coffee because it takes more time to develop on the tree and therefore gains more nutrients.
In reality, there's only minor losses going from a light roast and a dark roast - just 5.4%. This is not enough to have a noticeable impact on caffeine levels and certainly not enough to justify choosing a coffee based on roast alone.
Caffeine did not undergo significant degradation with only 5.4% being lost under severe roasting. Source
One theory that has been proposed is that the blend may be all or mostly Robusta coffee beans to boost the caffeine. This would indeed boost the caffeine content, and cost less to manufacture as Robustas are typically less expensive.
The significant problem with this theory is that Robustas are generally not great tasting, and a light roast would do nothing to mask those flavors.
Once consideration is that the roasting process does transform Chlorogenic Acids (CGAs), which has been attributed to many of the health benefits of coffee.
It's important to note however, that different origins and blends will have different levels of CGA, and can vary so widely that a light roast of one origin may have the same levels of a medium roast of another origin. Purchasing a non-descript generic "white coffee" therefore doesn't necessarily mean it's healthier than another coffee, without the chemical analysis to back up the claim.
Flat White Coffee
In Australia a white coffee or a "flat white" can be any number of different espresso and milk of coffee and milk drinks. Starbucks has introduced the "flat white" into North America, but does not refer to it as a white coffee.
In the US and UK you will from time to time hear "coffee with milk or cream" referred to as white coffee, but has nothing to do with the coffee roast.
White coffee can also refer to a cup of instant with a dash of cold milk.
White Coffee Roast
White coffee beans are very lightly roasted coffees. A very light roast makes for a very unique drink that not everyone will appreciate, as the flavors can be very distinctive and strong. The beans are frequently denser than medium/dark roasts and that hardness can cause damage to a standard coffee grinder.
White coffee can be used in anything from a standard drip coffee maker to an espresso machine, as long as the right grind is used.
White Coffee Flavor
Lighter roasts lead to more of single-origin flavours showing through a brew, as opposed to darker roasts which give coffee it's traditional flavor. This means that there's a wide variation in flavor between different brands, who may not identify what country's coffee they use in their blends. Because of this, it's recommended to order white coffee by country, as single origins will generally share common taste characteristics.
Coffees from Colombia and Brazil will tend towards milder, nutty-like flavors. African coffees from Kenya or Ethiopia will be more earthy and Indonesian coffees from Sumatra will have more of a spice-based flavor profile.
During the roasting process, many of the healthy anti-oxidants and acids that give coffee its health benefits are burnt off - the longer (and darker) a coffee is roasted, the fewer there are. White coffee's very light roast therefore retains more of the plant-based chemicals that provide health benefits. It's a reasonable assumption therefore that white coffee is better for you than other roasts, however there has not been research done to confirm this.
However, in non-organic coffees, the roasting process also removes all traces of pesticides/herbicides and fertilizers, which makes it safe to drink. In white coffee, as with tea, trace amounts of harmful chemicals may be present, depending on the roasting temperature used.
White Rhino Coffee
White Rhino Coffee is a cafe in Cedar Hill, Texas. It has nothing to do with the "White Coffee" drink.