Effect of Aloysia citrodora Essential Oil on Biochemicals, Antioxidant Characteristics, and Shelf Life of Strawberry Fruit during Storage.

Strawberry fruits are highly susceptible to cold burning, resulting in low storage periods at low temperatures. Plant extracts or essential oils (EOs) can potentially be used as preservatives in fruits throughout the refrigerated period. In the present study, the biochemicals, antioxidant characteristics, and shelf life of treated strawberries with Aloysia citrodora essential oil (ACEOs) were evaluated during keeping time. The treatments were produced as follows: T1, control; T2, 250 ppm ACEOs; T3, 500 ppm ACEOs; and T4, 750 ppm ACEOs. Total soluble solids (TSS), weight loss, titratable acidity (TA), antioxidant activity (DPPH assay), total phenolic (TPC), flavonoid and anthocyanin contents (TFC), and enzymes activity (peroxidase and ascorbate peroxidase) were evaluated during the refrigerated period (5 °C with relative humidity of 85-90% for 20 days). The results revealed that weight loss and TA were reduced in all treatments during storage, being that the rates were lower in samples treated with ACEOs. TPC, TFC, TSS, antioxidant, and enzymes activity were higher in treated fruits than control.

ɛ-polylysine coating with stinging nettle extract for fresh beef preservation.

Combination effects of ɛ-polylysine coating (0.5 and 1%) and stinging nettle extract (3, 6 and 9%) on quality properties and shelf life of beef meat (2 × 2 × 2 cm) was evaluated at 4 °C for 12 days. The results indicated that ɛ-polylysine (ε-PL) coating with stinging nettle extract (SNE) had no significant effects on ash, fat, protein and moisture content among packaged beef samples in polyethylene bags (in atmosphere condition). At the end of storage, beef samples coated with 1% ε-PL and 9% SNE had significantly lower TBARS and TVB-N values compared to those found in control. Furthermore, 1% ε-PL coating with SNE 9% showed the highest inhibitory effects against molds and yeast, total viable counts (TVC) and coliforms during storage. However, sensory evaluation showed that samples coated with 1% ε-PL and 6% SNE had the highest scores for overall acceptability compared to the other groups. Based on the obtained results, ε-PL coating with SNE could be effectively used for extending the beef meat shelf life without negative effects on sensory attributes.

Combined effects of ε-polylysine and ε-polylysine nanoparticles with plant extracts on the shelf life and quality characteristics of nitrite-free frankfurter-type sausages.

In this study, ɛ-polylysine (ɛ-PL) or ɛ-polylysine nanoparticle (ɛ-PLN) combined with plants extracts (including green tea, olive leaves and stinging nettle extracts) were used as nitrite replacers in frankfurter-type sausages. The sausage samples were wrapped in polyethylene bags (in vacuum conditions) and their physicochemical, microbiological and sensory properties were evaluated during 45 days of refrigerated storage. The results showed that the incorporation of ɛ-polylysine had no significant effects on proximate composition of sausages. However, ɛ-PL and ɛ-PLN sausages had significantly (P < 0.05) lower lightness, redness and higher yellowness compared to control samples. At the end of storage, sausages formulated with ɛ-PLN had significantly (P < 0.05) higher contents of phenolic compounds and lowest TBARS values. Microbiological counts also indicated that ɛ-PLN displayed significantly higher inhibitory effects. Higher sensory indices were obtained in ɛ-PLN sausages. Based on the obtained results, ɛ-PLN was effective to improve frankfurter-type sausages shelf life. Therefore, these ingredients could be useful for frankfurter-type sausages production as nitrite replacers.