Delta Tostadoras
Production drums, Campana, Buenos Aires Province, Argentina.
History
Delta Tostadoras is a small Argentine firm based in Campana, in the province of Buenos Aires. It presents itself as a company for developing and manufacturing roasting machines. The production workshop is in Campana, and the machine is announced as an entirely national development. The site tells of more than ten years of passion for coffee, then years of studying the science of roasting. This long development explains a late timeline. The first machine, the gas-fired DT250G, reached the market only in 2023. The electric version, the DT250E, followed. The target is stated plainly: the micro-roaster, and the neighborhood café that wants to develop its own product. This also says why the firm stops at two kilos per batch. It does not sell only machines, moreover. It gives a course on the fundamentals of roasting, roasts to order and welcomes visitors in its own roasting workshop. The price is displayed in dollars, at the official exchange rate, and the manufacturer takes care to say so. The mention is not trivial in a country where several dollar rates coexist. Without it, the figure would mean nothing. Each machine is built to order, in forty-five days, against a sixty percent down payment. The balance is due before shipment. The data sheet gives only one name, that of the engineer Mariano E. Santillan, as contact.
What it makes
A horizontal drum, heated by a radial gas burner on the DT250G, by electric resistances on the DT250E. On the gas version, the flame does not lick the sheet metal. The data sheet bears the notation apantallamiento de llama, that is, word for word, a flame screen. The drum of the DT250G is double-walled, in SAE 1010 steel of 4 mm. The layer of air trapped between the two walls limits the temperature of the inner wall. Conduction, that is, the heat the bean takes from contact with the metal, is therefore deliberately restrained. The stated aim is to avoid surface defects at full power. The Productos page gives the DT250E a single drum of 5 mm, which the data sheet does not confirm. The front and rear end plates are 5 mm thick and serve as a heat reservoir. The manufacturer says why: they give back their heat during charging, which makes it possible to charge at a lower temperature. The body is insulated with rock wool. The contribution by convection, the heat carried by moving air, is adjusted separately. It goes through an air inlet and a variable-flow fan. The rotation is adjusted too, from 0 to 80 revolutions per minute, with a 90 W motor on a variable-speed drive. A cyclonic separator holds the chaff of the bean in a removable bin. Five measurement points feed a liquid crystal display and the Artisan software: bean temperature, air temperature, preheating percentage, gas pressure, speed.
The models
A single platform, the DT 250, in two versions. The gas DT250G, radial burner, with pressure measurement from 0 to 40 mbar and a safety valve that cuts the supply if the flame goes out. Its drum is announced as double-walled, 4 mm. The electric DT250E, adjustable 4,500 W resistances, on a 25 amp outlet. The Productos page gives it a single 5 mm drum. Nominal capacity of 2 kg per batch, maximum charge of 2.3 kg. The manufacturer announces an even roast from 250 g to 2 kg, a ratio of one to eight between the smallest and the largest batch. Up to 40 kg of green per day, on seven-hour days. The first crack, that cracking of the bean that opens the usable roasting range, comes at ten minutes on gas with 2 kg, and at fifteen minutes on electric. Cooling 2 kg takes four minutes. Both versions require a four-inch air outlet. Displayed public price, 6,100 dollars excluding tax, installation, commissioning, roasting course and twelve-month warranty included. Travel costs are negotiated separately. No other machine is documented, neither a larger one nor a sample one.
What you gain
On the gas version, the double wall and the flame screen restrain conduction. The inner wall therefore stays cooler than a single drum placed over a flame. A 250 g batch becomes workable in a 2 kg machine, without burning the surface of the bean. That is the whole point of the announced ratio of one to eight. The 5 mm end plates give back their heat during the temperature drop that follows charging. One therefore charges less hot, and the bean takes a gentler shock. Convection is dosed separately, through the airflow and the drum speed, without touching the burner. Two separate levers are better than a single one. And the 2 kg cool in four minutes, which stops the roast instead of letting it run on.
What you lose
What protects the bean slows the machine. Heat must pass through a screen, a layer of air and two walls before reaching the charge. A power correction therefore arrives late. One must anticipate instead of catching up. The power remains modest, 6,000 kcal/h, or about 7 kW for 2 kg. The electric pays even more dearly. Its 4,500 W amount to only 4.5 kW, and the first crack comes at fifteen minutes instead of ten. If its drum is indeed single-walled, it also loses the air layer that protected the bean on the gas version. The 40 kg per day fit in about twenty batches over seven hours, hardly more. The range stops there: nothing bigger takes over when the shop grows.