The deal, which was announced Friday, will see Richmond go to the US subsidiary of Oaktree Capital Management for £182m (€266m).
Ruby Acquisitions already owns European ice cream producer Roncadin. Richmond Foods will sit alongside current operations as the equity firm gathers a portfolio of frozen desserts businesses.
Oaktree's MD Caleb Kramer said: "Our goal is for Richmond to remain focussed on its core geographical market but, once combined with Roncadin, to leverage both companies' strong market positions and reputation for high-quality products to enable us to serve customers on a pan-European basis."
Richmond has been at the forefront of sector consolidation for some time, buying up fringe brands from other leading producers. In 2001 the firm bought part of Nestlé's ice cream business, acquiring leading ice lolly brands Orange Maid and Strawberry Mivvi.
The latest move represents a continuation of the increased merger and acquisition activity in Europe and worldwide, as companies shuffle their portfolios within the global food industry.
Chilled and frozen foods divisions provide the best options for companies looking to consolidate their reach, said PricewaterhouseCoopers food sector leader Neil Sutton.
Earlier this year he told FoodandDrinkEurope.com that the global food market is still in the midst of ongoing merger and acquisition activity.
"There's still a lot happening in the sector. It's a very unconsolidated market relative to the retail sector it supplies. Manufacturers are constantly getting beaten up by retailers," he said.
"So I think there will be lots of movement in frozen and chilled foods in the coming months," he added.
Sutton sees investment in the frozen foods industry as a fairly solid venture for companies looking to consolidate their interests in this area.
"In Europe there is a general trend towards chilled foods, and this is most prominent in the UK. But a frozen foods brand can move to chilled, much like the Marie brand in France," he said.
However Unilever, Heinz, and Kraft have been eking low or negative returns from their frozen food divisions in a generally stagnant European market. The companies have either been reorganising or selling off the underperformers in a bid to boost their overall returns on the continent.
This is providing prime opportunities for investment firms to buy up off-cut brands and build pan-European and global portfolios that may become attractive to the larger manufacturers, like Nestlé, in the future.
Earlier this year Nestlé achieved full ownership of Dreyers Grand Ice Cream Holdings, giving it a 23 per cent share of the US ice cream market, according to figures from AC Nielsen.
The move consolidates Nestlé's position in America, where it has recorded strong sales growth since merging its ice cream division with Dreyer's in 2003. Nestlé took a 67 per cent share of the merger company.
Nestlé also claimed that ownership of Dreyer's, together with its takeover of Delta Ice Cream in Greece, would fetch it a 17.5 per cent share of the global ice cream market.
The purchases have seen the firm, already the world's biggest food producer, taking the number one spot in ice cream off Unilever for the first time.