Rosemary (Rosmarinus officina/is L.) is a plant of the genus Rosmarinus in the family Labiatae, native to the Mediterranean coastal region. As a natural spice plant, rosemary has a long history of cultivation and consumption.

Studies have confirmed that rosemary is rich in many polyphenolic substances such as salvianic acid, salvinorin, rosmarinol, rosmarinic acid, etc., and has a variety of physiological active functions such as antioxidant, antibacterial, anti-inflammatory, anti-tumor, and anti-gastric ulcer.

As a natural, safe and efficient antioxidant and antimicrobial agent, rosemary extract has been approved to be used as a food additive in China as well as in the European Union and other countries and regions, and its application in the field of food preservation and safety control has received wide attention.

Application of rosemary extract in fats and oils

Unsaturated fatty acids in fats and oils are highly susceptible to oxidation during processing and storage, which significantly reduces their nutritional value and organoleptic quality. In addition, oxidation products such as malondialdehyde, propionaldehyde and 4-hydroxynonenal (4-HNE) produced by the oxidation of fats and oils can cause serious health hazards.

Currently, the addition of antioxidants is one of the effective measures to prevent the oxidation of fats and oils. Compared with synthetic antioxidants, rosemary has been widely recognized for its antioxidant activity and safety.

As reported in the literature:
1. The addition of rosemary extract and rosemary essential oil to algal oil in the range of 0.02%-0.04% can effectively inhibit the oxidation reaction of algal oil and inhibit the elevation of thiobarbituric acid reactants and peroxide value.

2. The additive amount of rosemary extract in macadamia oil was about 0.02-0.1%, and when the additive amount was 0.08%, rosemary was able to prolong the induction time of macadamia oil by 2 times, which could effectively prolong its storage time.

3. Rosemary extract in soybean oil at 1000mg/kg, the addition of rosemary extract was able to inhibit the oxidation of soybean oil at 180℃, which could prolong the stability of soybean oil from 7.52h to 13.5h, and reduce the content of polar compounds from 17.35% to 7.99% of the control group.

4. The amount of rosemary extract added to linseed oil is about 200mg/kg, the addition of rosemary extract (400mg/kg) can inhibit linseed oil in the process of high-temperature storage (60 ℃, 0-7 days) peroxide value, anisidine value and other oxidation indexes increased, and its antioxidant effect is better than that of 100mg/kg of α-tocopherol and 200mg/kg of BHT.

The addition of rosemary extract can effectively inhibit the lipid oxidation reaction and prolong the shelf life of edible vegetable oils such as soybean oil, rice bran oil, rapeseed oil, linseed oil and animal fats such as fish oil and ghee during processing and storage.

In addition, the addition of rosemary extract (400mg/kg) can improve the stability of α, β, γ-tocopherol during high temperature storage (62℃, 24 days).

In addition to effectively inhibiting the oxidation of fats and oils, rosemary extract was also effective in improving the quality of fried foods.

According to Lalas and Dourtoglou, the addition of rosemary extract to blended oils significantly enhanced their antioxidant activity, inhibited color change and rancidity during use and significantly improved the sensory quality of potato chips.

Rosemary extract
Application in meat preservation

Due to its high fat content and rich nutrition, meat products are very susceptible to oxidation and microbial contamination during processing and storage, which not only cause the reduction of nutritional and sensory quality of the products, but also lead to foodborne diseases.

In recent years, scholars at home and abroad have conducted a lot of research on the application of rosemary extract in the preservation of meat products. Relevant studies have confirmed that the addition of rosemary powder, extract or essential oil can effectively inhibit the generation of lipid oxidation products such as thiobarbituric acid reactive substances (TBARS) and hexanal during the storage process of meat and meat products, effectively inhibit the oxidation of proteins and better maintain the organoleptic quality of the products, and have a good effect of color protection.

In addition, the addition of aroma is also enough to inhibit the growth and reproduction of pathogenic bacteria and spoilage-causing bacteria on the surface of meat products in the process. For example, Zhang et al. found that the addition of 1% (V/W) of rosemary extract had a good preservation effect on fresh chicken, and the total number of surface colonies of chicken samples, lactobacilli, enterobacteria, and Pseudomonas spp. of the rosemary extract-treated group were lower than those of the blank control group.

Rosemary extract can also be used in combination with other processing techniques to enhance its preservation effect. For example, Huang et al. found that the addition of 2.5% and 5.0% (W/W) of rosemary extract during supercritical CO2 treatment of minced meat was effective in reducing the physicochemical indexes such as total colony counts, pH, and volatile salt base nitrogen (TVB-N) during storage, which was better than supercritical CO2 treatment alone.

According to the literature:
1. The amount of rosemary ethanol extract added to pork meatballs was about 1%-1.5%, and the addition of rosemary extract could effectively inhibit the increase of MDA content in pork meatballs during storage and better maintain the sensory quality of the products.

2. The amount of rosemary essential oil added to chicken breast meat was about 2%, and the addition of 2% rosemary essential oil combined with vacuum packaging could inhibit the number of lactic acid bacteria and Pseudomonas aeruginosa in chicken breast meat samples during the storage process (4℃, 16 days).

3. The use of rosemary extract in chicken meat at an amount of about 0.02% was able to effectively inhibit the increase of TBARS content in the samples during storage (4℃, 21 days), and its effect was similar to that of 00.01% BHT.

Rosemary extract
Application in aquatic products processing and preservation

Due to high protein content, high water content, rich in unsaturated fatty acids, aquatic products are easily contaminated by microorganisms in the process of storage, transportation, processing and sales, causing spoilage and even foodborne diseases. The application of natural extracts with good antibacterial effect in the preservation of aquatic products has received wide attention.

Research has confirmed that the use of rosemary extract, rosemary essential oil and other pre-treatment and combined with vacuum packaging, refrigeration and other technologies can effectively inhibit sardines, finfish, Pacific white shrimp and other aquatic products in the storage process, TBARS, volatile saline nitrogen (TVB-N), peroxide value (PV), free fatty acids (free fatty acids) and other indicators. Free fatty acids (FFA) can effectively delay oxidative deterioration and microbial growth, and improve the sensory quality of the product and extend its shelf life.

In addition, rosemary essential oil and other essential oils are also used in the preparation of food packaging film, especially edible film, which has been proved to have a good effect on the preservation of aquatic products.

According to the literature:
1. 10g/L aqueous solution of rosemary extract was used to soak and treat sardine fillets for 4 minutes, and after vacuum packaging, it could effectively inhibit the elevation of indicators such as TBARS, TVB-N, PV, FFA and the growth of microorganisms of samples during storage, and prolonged the shelf-life of the products from 13 days to 20 days.

2. The rainbow trout was soaked in 4% rosemary essential oil nanoemulsion solution for 3 minutes, and then stored at 2℃ for 24 days after stretch film packaging.

Rosemary extract
Application in other food preservation

Rosemary and its extracts are also widely used in the preservation of fruits and vegetables, cheese, fresh pasta products, etc. Moradian et al. found that rosemary extract/bacterial cellulose film could effectively reduce the weight loss rate and the total number of surface chilling bacteria of double-hugged mushrooms during the storage process, and at the same time maintain the sensory quality and nutritional value of the products well.

Teodoro et al. prepared microencapsulated rosemary essential oil and applied it to fresh dough preservation. The experimental results showed that the addition of microencapsulated rosemary essential oil could effectively inhibit the growth of yeasts and molds in raw dough during storage (25°C, 12 days), and its inhibitory effect was superior to that of rosemary essential oil treatment.

Conclusion.

Because of its good antioxidant, anti-microbial and other active functions, rosemary extract has a broad application prospect in the field of food preservation. In recent years, scholars at home and abroad have conducted a lot of research on the application of rosemary extract in food preservation.

The experimental results showed that rosemary and its extracts can effectively inhibit the oxidation and spoilage of fats and oils, meat products, aquatic products, etc., and maintain the nutritional value and organoleptic quality of the products better. In the future work, we should optimize the treatment process parameters and focus on the research and development of the composite preservation technology of rosemary extract for the nature difference of various food materials to achieve the best preservation effect.