Conagra Brands, the Chicago-based food manufacturer that makes Reddi-wip, confirmed Monday that its supply of nitrous oxide — a propellant for aerosol toppings — was affected by the blast. Spokeswoman Lanie Friedman said stores still have the product in stock, but supplies may be limited in the peak holiday season, when consumers are indulging in pies, hot chocolate and other desserts that call for whipped cream.