My friend Michelle called me last week from the grocery store to ask if it was OK to buy some Mott's Applesauce that featured a K inside a triangle. My answer, like so many answers to Jewish questions, was, "it depends."
Over the years, the debates swirling around various Kosher symbols (hashgacha) have focused on one or another designation's strictness, level of observance, etc. Among the most controversial is the very same Triangle-K my friend found. The same symbol appears on products like Del Monte canned vegetables and Hebrew National hotdogs and it seems that there's no good answer to the Triangle-K question.
Baruch on Chowhound writes, "So with the case of Triangle K, some things are fine for people due to the inherent nature of the product, while others are more complex. For some, the hashgacha may be able to handle the supervision of simpler products like applesauce, but meat is too complex a product and some people are not comfortable with that hashgacha handling it."
Vague enough for you?
My best advice for kosher-keeping neophytes or those who simply want to avoid any snafus at their next Shabbat dinner or Passover seder, is to check out this Website: http://www.kashrut.com/agencies/.
It offers a pretty comprehensive list of what is and what isn't a widely-accepted stamp of rabbinical approval and includes everything from the nearly ubiquitous OU and Star-K to the obscure Kosher Kiwi of New Zealand. That said, it does not include Triangle K.