There are more than 100 bottles of mostly tequila, mezcal and other Mexican spirits by independent and craft producers on offer in the 10-seat bar, which is open from 7pm to midnight from Wednesdays to Saturdays.
"It's a platform to educate people on agave spirits because that's an up-and-coming category of spirits. It has been rising for the last 11/2 years globally and has really started to catch on," says Mr Zachary De Git, 28, who runs the programme with co-head barman Peter Chua, 29.
"We see it as an opportunity to bring the world of agave spirits to Singapore and show that these are not just drinks you have a shot of in a club."
AGAVE SPIRITS 101
Agave plants are harvested by farmers called jimadors when they reach full maturity, which can range between eight and 25 years.
The heart of the agave, the pineapple-shaped pina, is removed from the ground and taken to a distillery, where it is cooked to convert its high starch content to sugar for fermentation.
Juice is extracted from the cooked pinas, fermented, then distilled into concentrated alcohol before being aged in oak barrels.
Tequila and mezcal are regulated by Norma Oficial Mexicana, with tequila under the Consejo Regulador del Tequila and mezcal under the Consejo Regulador del Mezcal.
He notes that like whisky, wine and beer, agave spirits have "their own history and culture, and the way they are produced is very unique".
Although tequila and mezcal are both made from agave, they have different flavour profiles owing to their production processes. Tequila is largely manufactured on an industrial scale, but mezcal remains an artisanal distillate.
With Junior, it is also about making the spirits accessible.
"We wanted to create a programme where experienced drinkers can appreciate and enjoy agave spirits, but which wouldn't scare away people who are not familiar with them," says Mr Chua.
The bar's collection of tequila, for instance, includes familiar names such as Don Julio Reposado, which costs $16 for a 30ml shot. There is also premium stuff such as the Fuenteseca 21-year Extra Anejo, which is among the world's longest aged tequilas and will set you back $72 for a 30ml pour.
Agave spirits are already used in cocktails in Crackerjack, such as the mezcal negroni, but there is an entirely agave spirits-focused cocktail menu in Junior, with prices ranging from $20 to $25. Drinks include Raicilla When I See Ya, made with La Venenosa Raicilla Costa de Jalisco, passionfruit shrub, fino sherry and fresh mint; and the more traditional Paloma, typically made in Mexico with tequila, grapefruit soda, lime and salt.
But with so many variables in terms of production and interpretations of the spirits, Mr De Git's recommendation is to "find one you like and keep enjoying it".
"Be adventurous and try different things. If you don't like it, move on and try something else."
By law, tequila can be made from only the blue weber agave plant.
Flavour: Clean, easier-going flavours since agave hearts are steamed, or kilned, under high pressure. The best tequilas are 100 per cent blue agave, which is usually indicated on the label. Lower-quality tequilas made with fillers or additives are called mixto tequila. They have to be made with minimum 51 per cent blue agave distillate and the remaining amount can be filled with cane or neutral grain spirits. These are what give really bad hangovers.
Tequila also differs in taste, depending on whether it comes from the highlands (fruitier) or lowlands (earthier, more vegetal).
Produced in these Mexican states: Jalisco (most tequila is made here), Michoacan, Guanajuato, Nayarit, Tamaulipas
Production methods: More modern methods are used, such as steam cooking inside ovens (autoclaves). Fermentation involves starters (from a fermented batch) to kick-start the process or a proprietary yeast added by the distillery.
Distillation: Most are made in column or copper-pot stills and distilled at least two or three times, producing a cleaner product.
•Blanco (silver, white) - zero to 60 days of resting (in oak, but more commonly in plastic tubs/glass)
•Reposado (rested) - 60 days to a year, usually in larger oak barrels
•Anejo (aged) - one to three years in smaller oak barrels
•Extra anejo (extra aged) - three years and above
Like tequila, mezcal is made from pina, the heart of the agave plant, but it is produced using any of the 30-odd varieties of agave plants. Most are made with agave espadin.
Flavour: Mezcal traditionally has a smoky flavour that makes it distinguishable from tequila. It comes from the agave hearts being roasted in rocklined pits.
Produced in these Mexican states: Oaxaca (about 90 per cent is made here), Durango, Guanajuato, Guerrero, San Luis Potosi, Tamaulipas, Zacatecas, Michoacan, Puebla
Production methods: There are variations depending on the category: mezcal, artisanal mezcal or ancestral mezcal.
In "commercial" mezcal, processes such as autoclaves, fermentation in wood or stainless steel tanks, and column-still distillation are used.
But for artisanal or ancestral mezcals, pinas are typically cooked in underground earthen pits lined with hot rocks or elevated stone ovens. Along with an open-air fermentation process during which natural yeasts are typically used, the agave juice could be fermented in animal skins, hollowed-out tree trunks and other objects.
Distillation: Column stills or direct fire on copper/steel stills, clay pots.
•Joven (blanco, abacado) - zero to 60 days
•Reposado or madurado - 60 days to a year in oak
•Anejo - at least one year
Raicilla and Sotol
The less-known cousins of tequila and mezcal are raicilla and sotol. Raicilla is the sweeter, softer version of mezcal, and sotol is the grassy equivalent.
Like tequila, raicilla is made in Jalisco state, Mexico, but instead of blue agave, it is made of up to 18 varieties of wild or cultivated agave.
Pinas (the heart of the agave plant) are cooked in above-ground ovens or underground pits, depending on which region the raicilla is made in.
The spirit was once considered cheap, local moonshine, but agave advocates such as chef Esteban Morales of La Venenosa Raicilla are working towards having it officially recognised. La Venenosa Raicilla is stocked at Junior, a pocket bar at the back of restaurant Crackerjack.
Sotol is not made from agave, but from a sub-species succulent called the Desert Spoon. The plant is typically found in northern Mexico (Chihuahua, Coahuila and Durango) and grows in the wild.
Like tequila and mezcal, Desert Spoon hearts are steamed or roasted, but they take on the flavours of the terroir they grow in, such as forests or deserts. There is a lone Sotol La Higuera from Chihuahua available at Junior.
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