Berries are rich reservoirs of minerals, sugars, organic acids, vitamins, carotenoids, phenols and fatty acids. Berries include raspberries, which are highly valued and cultivated worldwide for their delicious taste.

Raspberry seed oil has a high content of polyunsaturated fatty acids (PUFAs), such as linoleic acid and alpha-linolenic acid. It is a rich source of vitamins A and E and is therefore also used in cosmetics as an effective skin moisturizer, emollient and antioxidant as well as a photoprotective agent.

The process of extracting oil from seeds generates some waste, for which reduction and recovery strategies need to be developed.

Since only about 9% of the oil is extracted by cold pressing, almost all of the starting biomass is wasted. The remaining defatted portion is a rich source of bioactive compounds.

The study

The present work, published in Pharmaceutics, examines a strategy to valorize defatted raspberry seeds and obtain valuable ingredients with potential application in skincare formulations.

The oil was extracted by taking advantage of cold-press extraction technology. The remaining portion of defatted raspberry seeds was treated with three proline-based Deep Eutectic Solvents (DES) to obtain polyphenols.

The first stage of the analysis involved chemical characterization of the cold-pressed oil, optimization of the green extraction procedure of the bioactive components from the defatted seeds, determination of total phenolic content (TPC) and radical scavenger activity (RSA) in the extracts, quantification of free ellagic acid and total ellagic acid in the extracts by liquid chromatography, and selection of the most efficient proline-based DES system for extraction of phenolic compounds.

The proline/citric acid extract was the most potent, with free and total ellagic acid contents of 52.4 mg/L and 86.4 mg/L, respectively, total phenolic content (TPC) of 550.1 mg GAE/L and radical scavenger activity (RSA) of 4742.7 mmol TE/L.

After selecting the most important extract, the experiment was aimed at obtaining the cosmetic formulation and evaluating its characteristics.

Two prototypes were set up: an emulsion by direct mixing of the selected extract into the control sample (hand cream) and a microemulsion by encapsulation with starch as vehicle.

The two preparations were characterized by evaluation of irritation potential (Zein test) and transepidermal water loss (TEWL), red blood cell (RBC) test and DPPH antioxidant test.

Both were of better quality than the control hand cream, with low skin irritation effect, lower transepidermal water loss (TEWL) and higher antioxidant potential.

Conclusions

The agribusiness sector produces a huge amount of unavoidable waste material that, in most cases, can be reused.

The above study complies with circular economy principles and green technology standards. It is therefore set up as an efficient model for the reuse of natural resources through waste minimization.

However, more detailed chemical studies are desirable to clarify the composition of by-products from raspberry seed oil processing and their value as promising raw materials for the beauty industry.

Translated with DeepL.com (free version)

Ćirić I, Dabić Zagorac D, Sredojević M, Fotirić AkÅ”ić M, Rabrenović B, Blagojević S, Natić M,Ā Valorisation of Raspberry Seeds in Cosmetic Industry-Green Solutions, Pharmaceutics. 2024; 16(5):606. https://doi.org/10.3390/pharmaceutics16050606

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