Our first quarter revenue of $1.06 billion declined only 2.5% from last year's sales.
We estimate that last year's first quarter benefited by $66 million as consumers navigated the early days of the pandemic.
In the first quarter, we made solid progress in expanding adjusted EBITDA margins, which improved 20 basis points versus last year.
Adjusted earnings per share of $0.36 was also strong and just shy of last year's first quarter.
These categories represent about 40% of our portfolio and are characterized by strong consumer trends, defined pockets of growth and existing depth where we have meaningful opportunities to go further.
The cash engine categories comprised another 40% of our portfolio.
The remaining 20% consists of categories where we are reviewing our opportunities to either revitalize the businesses or to deploy that capital elsewhere.
When you compare March of 2021 to two years ago, or 2019, total edibles grew 14%, and private label grew 13% in measured channels.
We've also restored service levels back to the pre-pandemic levels in the 98% range.
Meal Prep net sales grew 0.7% versus the first quarter of 2020.
Riviana contributed approximately $40 million, more than offsetting the comparison to last year's COVID-related food demand surge and continued weakness in food-away-from-home consumption.
Snacking & Beverages declined 7.9% driven by the comparison to the initial wave of pantry stocking in the last few weeks of March and our sale of two in-store bakery plants.
Excluding that impact of that divestiture, which will be behind us in April, revenue declined 3.9%.
After excluding the sales associated with the two in-store bakery plants, total sales in the retail channel declined $18 million versus last year.
We also estimate that the net revenue headwind in the quarter related to weather totaled about $4 million, which we do not expect to recover, we are encouraged by the progress as Riviana acquisition and base business growth nearly offset the $66 million related to pantry stocking last year.
Volume and mix, including absorption, were negative $0.15.
Pricing net of commodities, or PNOC, was a $0.28 drag on the quarter as we faced significant inflation across commodity and freight complex.
Operations added $0.27 in the quarter due primarily to planned performance as well as the benefit of the Riviana Pasta business in the quarter.
SG&A contributed $0.09 year-over-year due to the timing of lower expenses.
Other income added $0.06 driven by investment gains as we lap the market volatility from last year.
As I noted on our February earnings call, we have begun the redemption process of our 2024 notes, calling $200 million.
Following that, we successfully upsized and extended the maturity of our term loans and used the proceeds to redeem the remaining $403 million of our 2024s.
For those of you that track our financial leverage ratio, we finished the quarter at 3.6 times.
I will point out, that represents a more straightforward net debt to last 12 months adjusted EBITDA calculation versus our bank covenant leverage ratio, which is more complex.
We continue to target our financial leverage ratio in the range of three to 3.5 times.
In our guidance for the year, we estimated agricultural commodity inflation of between $100 million and $110 million as well as higher freight and labor costs.
As we sit here in May, we are now facing commodity inflation of about $60 million: $40 million which relates to ingredients and another $20 million in freight.
On Slide 16, we shared our detailed full year guidance, reaffirming our ranges of $4.4 billion to $4.6 billion of revenue, $2.80 to $3.20 for adjusted earnings per share and free cash flow of approximately $300 million.
As we consider the higher cost environment and the timing for pricing recovery, we have revised our expectations and now anticipate about 20% of our earnings to come in the first half with the remaining 80% in the second half.
This compares to our original expectation for 30-70 first half, second half split.
While this does put a bit more pressure in our second half earnings delivery, I will point out that our 20-80 cadence is not dissimilar to 2018 when we took similar actions to offset inflationary headwinds.
We're anticipating $1.02 billion to $1.07 billion of revenue and $0.20 to $0.30 in adjusted earnings per share as inflationary pressure will not yet be offset by our pricing actions.
In the first quarter, we invested $16 million, and we anticipate these investments to total $75 million in 2021 as we enhance our commercial capabilities and advance our supply chain so that customers view us as their partner of choice.
As I mentioned earlier, the learnings we have accumulated from our strategy and the pandemic are shaping how we'll position ourselves for the future, including how we'll invest in the 40% of our portfolio that represents our growth engine businesses and leverage the cash that we generate from our cash engine categories.

Summary:
Our first quarter revenue of $1.06 billion declined only 2.5% from last year's sales.
Adjusted earnings per share of $0.36 was also strong and just shy of last year's first quarter.
On Slide 16, we shared our detailed full year guidance, reaffirming our ranges of $4.4 billion to $4.6 billion of revenue, $2.80 to $3.20 for adjusted earnings per share and free cash flow of approximately $300 million.
We're anticipating $1.02 billion to $1.07 billion of revenue and $0.20 to $0.30 in adjusted earnings per share as inflationary pressure will not yet be offset by our pricing actions.