New startup business - to compare different food brands

See What you're trying to do is fine as long as you are comparing the fact based Information which is available in the public domain. You can showcase two products their contents, their ingredients, the way they are manufactured, the way they are marketed and anything which is based on the fact and information. The moment you start giving judgmental views on the product which can turn into defamatory statements then the product owner might go against you and file a case of defamation.
Having said that As long as you're comparing two brand and It's not breaching any prevailing laws or not committing defamation you are safe to do this.

Dear Client,

For an online food-brand comparison platform, you may generally use purely factual, non-creative information from brand websites such as product names, ingredients lists, nutritional values, prices (if publicly listed), pack sizes, allergens, certifications, and objectively verifiable claims, provided the data is accurate, not misleading, and properly attributed; independently collected or verified data is safest.

However, you cannot copy or reproduce copyrighted content such as product descriptions, marketing text, images, videos, layout, slogans, or comparative charts, nor can you use logos or trademarks in a way that suggests endorsement or affiliation. Scraping data may violate a brand’s Terms of Use, so review and comply with them, consider APIs or permissions where available, and avoid bypassing technical protections.

Dear client,

When starting an online platform to compare different food brands, it is important to comply with intellectual property laws, data protection rules, and unfair competition regulations.

Data that can generally be used:

Publicly available factual information, such as product name, ingredients list, nutritional values, price, weight/quantity, shelf life, and certifications (FSSAI number, vegetarian/non-vegetarian mark), provided it is reproduced accurately and without alteration.

Independent analysis, reviews, ratings, and comparisons created by your platform, based on your own methodology.

User-generated reviews and feedback, subject to proper moderation and compliance with IT rules.

Brand names and trademarks, only to the limited extent necessary for identification and comparison, without suggesting endorsement or association.

Data that should NOT be used without permission:

Copyrighted content such as brand website text, marketing descriptions, slogans, images, videos, brochures, or packaging designs.

Logos, brand creatives, or trade dress in a manner that may cause confusion or imply partnership.

Proprietary or confidential information not publicly disclosed by the brand.

Scraped data in violation of a brand’s website terms of use.

Legal precautions recommended:

Ensure comparisons are objective, verifiable, and non-defamatory.

Avoid misleading claims or rankings that cannot be substantiated.

Publish clear disclaimers stating that the platform is independent and not affiliated with the brands listed.

Comply with IT Act, Consumer Protection Act (misleading advertisements), Copyright Act, Trademark Act, and FSSAI advertising norms.

Before launch, it is advisable to consult an advocate to review the platform’s content structure, disclaimers, and data sourcing model to reduce the risk of IP infringement or unfair trade practice claims.