In February, Senator Nash demanded a website for the Health Star Rating system be taken down a day after it was published. The controversy sparked claims of conflict interest that ended with the resignation of Senator Nash's then chief of staff, Alastair Furnival after Fairfax Media revealed he was the co-owner of a lobbying firm which had represented junk food clients.

On Saturday, health groups who had been critical of Senator Nash's earlier decision to pull the website appeared beside her outside a Canberra shopping centre to celebrate its rebirth.

Senator Nash said the rating system, the product of more than two years of collaboration between federal, state and territory governments, health and consumer groups and the food industry, would make it easier for shoppers to make informed choices about healthier food options.

"The five-star ratings clearly displayed on packaged foods will allow consumers, especially parents, to Healthymake healthy food choices for the whole family without spending hours reading labels at the supermarket," she said.

Under the system, products are assigned a score of between half a star and five stars according to their energy, fat, sugar and salt content.

The healthier the food, the higher the number of stars it will receive.

Eleven companies have signed up to the voluntary system so far, and seven already include the star ratings on their products. Sanitarium, SPC and Coles are among the brands which are already displaying star ratings on their products.

Senator Nash has dropped the threat, made by federal, state and territory food ministers during the former Gillard government, to make the scheme mandatory if an insufficient number of manufacturers voluntarily adopt it.

Companies will be encouraged to add the ratings to their products over the next five years, and a review of the level of take up will be conducted in June 2016.

Senator Nash said she had been encouraged by the interest companies had shown in adopting the rating system, and said they should be given time to apply it to their products.

"I think we need to give them the benefit of the doubt for a while," she said.

Appearing beside Senator Nash, Public Health Association chief executive Michael Moore acknowledged the development of the rating system had been a "rocky process" but paid tribute to Senator Nash for steering it through to completion.

"We thank Minister Nash for her determined work to make this a reality," Mr Moore said.

The chief executive of the National Heart Foundation, Mary Barry, who also joined Senator Nash at the launch, congratulated the minister for delivering the scheme, which she said would encourage companies to reformulate their products to make them healthier.

Obesity Policy Coalition executive manager Jane Martin welcomed the launch but said she was disappointed that companies would be allowed to continue using the "potentially misleading" daily intake guide favoured by some manufacturers in addition to the star rating panel. She said it was crucial that there was widespread and consistent adoption of the system by food makers, so that people could compare the nutritional value of similar products across brands.