Stars, Tokens and Premium Items

Kitchen Scramble requires a minimum number of coins earned to be able to move on to the next level. You can see the goal on the menu that pops up before each game.  On this level, you just have to earn a minimum of 100 coins to move on to the next.  If you earn lesser than the goal, you have to repeat a level, and you have to spend 10 supplies again.

If you mouse over the stars, you can see the required number you need to earn it.

One star will give you 1 token
Two stars will give you 2 tokens
Three stars will give you 3 tokens.

Keep in mind that you can earn more coins from tips, so the faster you serve the customers, the higher tip amount they are going to give you.  More tokens earned will help you open all the other levels of the game.
Here's a sample of where you will need those tokens to open up a location:

Let's talk about the premium ingredients.

Any dish that you will make with a premium ingredient will receive bonus coins.  It greatly helps increase the value of the dishes that you prepare.  You can earn these items as rewards for some of the levels, or you can ask from friends as gifts.  You can also purchase them for coins.  I do, however, suggest that you save your money during the early levels of the game, to upgrade the appliances first, rather than spend for the premium ingredients.  If you have some of the premium ingredients, it will show you how many you have at the start of the game. Click the ingredient to use it.  During the game, the premium ingredients sparkle as a reminder that they give you more coins when used.