Antioxidative activities of some peptides isolated from hydrolyzed potato protein extract

Three peptides (5A, 5C and 6C), purified from potato protein hydrolysate fractions, possessed antioxidative activities. Isolation and purification were carried out using gel permeation chromatography and successive reverse-phase HPLC. These three peptide fractions were sequenced and identified as Phe-Gly-Glu-Arg, Phe-Asp-Arg-Arg and Phe-Gly-Glu-Arg-Arg, respectively. The fractions 5A, 5C and 6C inhibited linoleic acid oxidation by 55.3%, 58.5% and 61.7% using β-carotene decolorization assay system, while the inhibition ratio was 32.1%, 93.0% and 93.4% in the ferric thiocyanate assay system, respectively. The peptide fractions 5A, 5C and 6C also repressed lipid oxidation by 24.2%, 14.7% and 26.4% in the erythrocyte membrane ghost assay system, respectively. Oral administration of 100 mg/kg of body weight of the chemically synthesized peptides, 5A, 5C and 6C to rats (male Wistar) 30 min prior to ethanol injection reduced ethanol-induced gastric mucosal damage by 67.9%, 57.0% and 60.3%, respectively. Conclusively, these peptides have shown real potent antioxidative activities and could further be investigated for potential use as food additives.     

Variation of Fructooligosaccharides and their Metabolizing Enzymes in Onion Bulb (Allium cepa L. cv. Tenshin) During Long-term Storage

ABSTRACT: The objective of this study was to assess the status of fructooligosaccharides (FOS) in onion bulbs ( Allium cepa L. cv. Tenshin) and their metabolizing-enzymes—1-fructoexohydrolase (1-FEH), 1-kestose hydrolyzing enzyme (1-KH), fructan:fructan 1^F-fructosyltransferase (1-FFT) and fructan:fructan 6^G-fructosyltransferase (6G-FFT)—during storage at 15°C. Fructose varies slightly, whereas 1-kestose peaked after 6 wk and then decreased progressively during the last 18 wk of storage. Lower degree of polymerization (DP) 3 to 6) FOS, higher (DP 7 to 12) FOS, total FOS, and total carbohydrates showed similar and close patterns during 24 wk. They varied slightly at the beginning of the storage period; afterward they decreased progressively and regularly during the last 20 wk of storage. 1-FEH and 1-KH activities were low but peaked abruptly after 12 and 16 wk, respectively, after which they decreased to levels higher (1-FEH) or similar (1-KH) to those observed at the beginning of the storage. Surprisingly, 1-FFT activity showed similar pattern to the variation of 1-KH hydrolyzing activity; on the other hand, 6G-FFT, although higher, was stable during 16 wk but decreased after that. The results allowed us to associate FOS to the dormancy and sprouting states, and the peaks of the degrading enzymes were shown to signal the release of dormancy of onion bulb.     

Potato Glycoalkaloids: occurrence,biological activities and extraction for biovalorisation – a review

Potato tuber (Solanum tuberosum L.) is the fourth most important agricultural product after wheat, rice and maize. With a total production of 388 million in 2017, c.a. 70% of this total production is processed in developed countries, producing a large amount of potato peel waste (PPW) as by-product. Although PPW is considered as a zero-value by-product by the feed industry because it is too fibrous, for other recycling industries it is an inexpensive by-product due to its significant contents of some interesting nutrients particularly polyphenols and glycoalkaloids. In potato, and Solanum species in general, many glycoalkaloids, predominantly α-chaconine and α-solanine, have been chemically and structurally identified. However, further research is needed to expand the knowledge of the biological values of potato glycoalkaloids in order to develop a recycling process to extract these technologically and nutritionally interesting bioactive ingredients for different sectors, in particular, the agricultural, food and pharmaceutical ones, which are demanding natural, safe and eco-friendly ingredients.     

Storage technology of onion bulbs c.v. Rouge Amposta: effects of irradiation, maleic hydrazide and carbamate isopropyl, N-phenyl (CIP) on respiration rate and carbohydrates

The effects of γ-irradiation, maleic hydrazide (MH) and carbamate isopropyl, N-phenyl (CIP) on the carbohydrate content, respiration rate (RR) sprouting and rotting of red onion bulbs ( Allium cepa L.) c.v. Rouge Amposta stored at 4, 10 and 20 °C were investigated. Between 6 and 8 weeks soluble sugars increased in concentration and varied between 6.0 and 6.5% fresh weight both at 10 and 20 °C. However, this peak did not exceed 6.0% fresh weight at 4 °C. The basal amount of soluble sugars was about 3% fresh weight. The content appeared to be influenced by temperature, with greater accumulation at 10 and 20 °C than at 4 °C. The RR increased when the bulbs sprouted, whereas it was reduced by the following treatments: irradiation, MH and CIP, the respiration of irradiated bulbs decreased during the final stage of storage because of the death of the sprouts. The chemical treatment used were effective in controlling sprouting of the bulbs during storage, although not as effective as irradiation and chilling.     

Respiratory parameters of onion bulbs (Allium cepa) during storage. Effects of ionising radiation and temperature

The O₂ and CO₂ respiration rates of untreated and irradiated onion bulbs (Allium cepa) at 0.15 and 0.30 kGy were measured at 4, 10 and 20 °C. The O₂ respiration rate increased for 24 h after treatment from 0.19 mmole kg⁻¹ h⁻¹ at 20 °C for control samples up to 0.26 and 0.39 mmole kg⁻¹ h⁻¹ for 0.15 and 0.3 kGy irradiated onions respectively. Respiratory quotient (RQ) increased with temperature. The Q₁₀ of the respiration of the control samples (1.61) was lower than that of any other plant tissue, but it increased with storage duration and irradiation dose. The respiration rate of control onions increased steadily over 25 weeks of storage at 4 °C, while that of the irradiated samples decreased during the same period after a peak observed after irradiation treatment. The apparent K_m for the Menten–Michaelis equation was determined on a new respirometer and averaged 1.6 kPa at 10 °C and 6.3 kPa at 20 °C. However, at this higher temperature (20 °C) apparent K_m varied with O₂ partial pressure, proving that the respiration of onion bulbs does not follow a Menten–Michaelis‐like process. The Fermentative Index (FI) of onions was measured under anoxic conditions as CO₂ production rates in mmole kg⁻¹ h⁻¹ at 4, 10 and 20 °C. © 2000 Society of Chemical Industry     

Postharvest physiology and technology of loquat (Eriobotrya japonica Lindl.) fruit

Loquat (Eriobotrya japonica Lindl.) is a subtropical evergreen tree whose fruit is consumed both fresh and processed. Loquat fruit is a good source of minerals and carotenoids, while the kernel is rich in protein and carbohydrates. It has been considered a non‐climacteric fruit, but there is evidence that some cultivars have a ripening pattern similar to that of climacteric fruits. The fruit has a short postharvest life at ambient temperatures and is susceptible to physical and mechanical damage, loss of moisture and nutrients, and decay. Low‐temperature storage extends the shelf life of loquat fruit, but some cultivars are severely affected by chilling injury and flesh browning during cold storage. Purple spot, browning and leatheriness are major postharvest disorders. The shelf life of loquat can be extended by modified or controlled atmosphere storage as well as by postharvest treatment with 1‐methyl cyclopropene or methyl jasmonate. © 2014 Society of Chemical Industry     

Assessment and profiling of the fatty acids in two ackee fruit (Blighia sapida Köenig) varieties during different ripening stages

BACKGROUND: The ripening of fruits is characterized by physical, chemical and biochemical compositional changes such as color, sugars and phenolic compounds. Ackee fruit is famous in Jamaica and the Caribbean. This study aimed to assess the variation of fatty acids in two varieties (cheese and butter) ackee (Blighia sapida) fruits during five different ripening stages. RESULTS: The total fatty acid content of ackee fruit was much higher in arils and ranged from 283.4 to 465.1 g kg^?1 dry weight (DW), while in husk they ranged from 235.2 to 465.1 g kg^?1 DW in both varieties. Total fatty acid content declined in the arils and the husks as the fruit ripened. Five major fatty acids were found: palmitic acid (C16:0) and stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2) and linolenic acid (C18:3). In the arils, oleic acid was found at the highest concentration, followed by palmitic, stearic, linoleic and last linolenic acid. The unsaturated:saturated ratio of fatty acids varied from 1.23 to 3.26 in the arils of both varieties, and from 1.03 to 5.05 in the husk. Monounsaturated:polyunsaturated fatty acids ranged from 8.56 to 25.19 in the arils and from 0.62 to 2.33 in the husk. CONCLUSION: The results show that ackee arils contain much higher levels of fats than the husk and the major fatty acid in the arils was oleic acid (Δ9‐cis‐oleic acid, an omega n‐9), while in the husk unsaturated fatty acids were higher than the saturated ones. Oleic acid was the major fatty acid in both varieties, and aril fatty acid content was 10–20 times higher than in the husk. In both varieties, unsaturated fatty acids were relatively higher than saturated ones; however, total fatty acids showed a decline with ripening for arils and husk tissues. © 2012 Society of Chemical Industry     

Variation in 1‐fructo‐exohydrolase (1‐FEH) and 1‐kestose‐hydrolysing (1‐KH) activities and fructo‐oligosaccharide (FOS) status in onion bulbs. Influence of temperature and storage time

Effects of storage temperature and duration on 1‐fructo‐exohydrolase (1‐FEH) and 1‐kestose‐hydrolysing (1‐KH) activities and trisaccharide (Tri) and fructo‐oligosaccharide (FOS) status in onion bulbs var Tenshin kept for 24 weeks at 10 and 20 °C were investigated. 1‐FEH activity peaked sharply after 10 weeks and seemed to be triggered by a decrease in sucrose content. 1‐KH activity increased during the first 8 weeks and remained stable during the last 8 weeks. Contents of Tri, FOS and total FOS decreased abruptly during the first 8 weeks; however, at 10 °C, contents of Tri, FOS (DP 3–12) and total FOS were lower than those at 20 °C. The consumption rate of fructo‐oligosaccharides also appeared to be higher at 20 °C than at 10 °C, despite the slight degradation in activities observed at this low temperature. 1‐FEH seems to be under the control of a triggering signal which induces its activity, and sucrose seems to be this biochemical signal which initiates dormancy release and the onset of sprouting, as found previously. Thus changes in carbohydrates seem to be a strong indicator of the end of the dormant state of the bulb and the beginning of the sprouting period. Copyright © 2004 Society of Chemical Industry