Effects of Irradiation on the Volatile Compounds of Garlic (Allium sativumL)

The effects of 0·15 kGy gamma irradiation on the content of volatile compounds in garlic bulbs during storage at room temperature were evaluated. The content of diallyl disulphide decreased immediately after irradiation. However, at the end of 8-month storage both irradiated and unirradiated samples showed a significant increase in diallyl disulphide.     

Effects of Gamma Irradiation Dose and Timing of Treatment after Harvest on the Storeability of Garlic Bulbs

The effect of gamma irradiation dose and time of treatment after harvest on the storage of garlic bulbs was investigated. The effectiveness of irradiation for external sprout inhibition was not affected by the treatment time within 45 days after harvest. At 285 days after harvest, irradiation of 50 - 150 Gy caused about 6% less decrease in weight loss compared with the unirradiated group, and spoilage rates of the unirradiated and irradiated cloves were 100% and 17 - 20%, respectively. For the overall storageability of garlic bulbs, 75 Gy was shown to be the minimal optimum dose, and there was no apparent effect depending upon the time of irradiation treatment after harvest.     

SENSORY QUALITY of IRRADIATED ONION and GARLIC BULBS

The radioinhibition process has shown to prolong shelf-life of "Valenciana sintética 14" onion variety and "Colorado" garlic variety. Sensory attributes of the irradiated bulbs were tested monthly by trained judges during extended storage in warehouse conditions (6-32C, R.H. 40–50%). the sensory properties observed were external and internal appearance, firmness and odor.
The irradiated bulbs were judged to be superior in quality with respect to internal and external appearance (p < 0.01) and firmness (p < 0.01), after 180 days postharvest. the irradiated bulbs showed no difference in odor (p < 0.05), when compared to unirradiated ones, through the storage period.     

Irradiation Effect on Onion Keeping-Quality After Sea-Shipment from Argentina to the Netherlands

Onion losses occur due to sprouting and rot. Onion cultivar Valenciana was irradiated with 60 Gy, shipped from Argentina to the Netherlands, and stored 6 months at 4°C. The rot in unirradiated samples increased after 4 months while rot in irradiated samples remained almost constant. Irradiation almost completely prevented sprouting. Storage losses were 50% for unirradiated and 20% for irradiated samples. Irradiated samples showed an improvement in general appearance. Irradiation reduced weight loss and damaged bulbs were more susceptible to storage rot.     

Physio-chemical behavior of γ-irradiated garlic bulbs under ambient storage conditions

The present study was undertaken to study the effect of different gamma irradiation doses on storage life of garlic bulbs under ambient storage conditions. Garlic bulbs (cv. PG-18) were irradiated with gamma rays in dose range of 0–0.2 kGy and stored under ambient conditions (Temp 27–35 °C and RH 34–76%). Physical and chemical quality parameters i.e. physiological loss in weight (plw), rotting, sprouting, total soluble solids, firmness, ascorbic acid and allicin content of garlic bulbs was determined fortnightly to assess its storage life. On 195th day of ambient storage, the weight loss of bulbs ranged from 32.22 to 38.48% in all irradiation doses. It was observed that upto 30 days and 150 days, there was no rotting and sprouting, respectively in all the treatments. Firmness, total soluble solids, ascorbic acid and allicin content were significantly different with storage period and irradiation dose levels. It is concluded that garlic bulbs irradiated @ 0.12 kGy of gamma radiation resulted in minimum post-harvest losses along with maintaining their marketable shelf life for 4 months under ambient storage conditions.     

Characterization of volatiles from cultured dairy spreads during storage by dynamic headspace GC/MS

The effect of storage time and storage temperature on the formation of volatile compounds in dairy spreads was investigated. Dairy spreads were stored for 10 weeks at -18, 5 and 20 °C, respectively, and analyzed after 0, 38, 54 and 67 days of storage. By means of a dynamic headspace GC/MS method using Tenax traps the dairy spreads were analyzed for volatile aromatic compounds. 61 components were identified and their relative content was followed during the storage period. Among these were four alcohols, 17 aldehydes, four esters, ten alkanes, 11 ketones and six lactones. A general increase in the concentration of most of the volatile compounds during storage was found. The content of volatile compounds in dairy spreads stored at -18 °C was nearly constant or showed a rather low increase in the content during the storage period. Storage at higher temperatures (5 and 20 °C) resulted in an increase in the content of most of the volatiles after 40 days of storage. The profiles obtained were subjected to multivariate data analysis to determine the volatiles potentially responsible for oxidized off-flavors in dairy spread. The volatiles were divided into three groups: one correlated with storage temperature and 5 °C, one with storage time and 20 °C and the last with storage time alone. Most of the volatiles were found in the highest concentration after storage at 20 °C, but the content of some volatiles was highest after storage at 5 °C.     

Effect of irradiation, active and modified atmosphere packaging, container oxygen barrier and storage conditions on the physicochemical and sensory properties of raw unpeeled almond kernels (Prunus dulcis)

BACKGROUND: The present study investigated the effect of irradiation, active and modified atmosphere packaging, and storage conditions on quality retention of raw, whole, unpeeled almonds. Almond kernels were packaged in barrier and high‐barrier pouches, under N₂ or with an O₂ absorber and stored either under fluorescent lighting or in the dark at 20 °C for 12 months. Quality parameters monitored were peroxide value, hexanal content, colour, fatty acid composition and volatile compounds. Of the sensory attributes colour, texture, odour and taste were evaluated. RESULTS: Peroxide value and hexanal increased with dose of irradiation and storage time. Irradiation resulted in a decrease of polyunsaturated and monounsaturated fatty acids during storage with a parallel increase of saturated fatty acids. Volatile compounds were not affected by irradiation but increased with storage time indicating enhanced lipid oxidation. Colour parameters of samples remained unaffected immediately after irradiation. For samples packaged under a N₂, atmosphere L* and b* values decreased during storage with a parallel increase of value a* resulting to gradual product darkening especially in irradiated samples. CONCLUSION: Non‐irradiated almonds retained acceptable quality for ca. 12 months stored at 20 °C with the O₂ absorber irrespective of lighting conditions and packaging material oxygen barrier. The respective shelf life for samples irradiated at 1.0 kGy was 12 months packaged in PET‐SiOx//LDPE irrespective of lighting conditions and 12 months for samples irradiated at 3 kGy packaged in PET‐SiOx//LDPE stored in the dark. Copyright © 2010 Society of Chemical Industry     

Total volatile acids content as a quality index of irradiated hake (Merluccius merluccius hubbsii) fillets

Irradiation of hake (Merluccius merluccius hubbsii) fillets with 500 krad (5 k Gy) of Co⁶⁰ gamma rays caused a delay in the formation of volatile acids during storage under refrigeration at 4–5°C. Loss in organoleptic acceptability could be correlated with the increase in volatile acids both in the unirradiated and irradiated fish stored at 4–5°C, suggesting that the volatile acids number (VAN) can be a useful tool for the quality evaluation of hake fillets.     

Storage quality of chopped garlic as influenced by organic acids and high‐pressure treatment

The storage quality of chopped garlic from bulbs in both dormant and dormancy‐terminated states with or without citric and/or ascorbic acids was investigated. The chopped garlic plus acids was also treated under high hydrostatic pressure (600 MPa, 1 min). Quality attributes of processed garlic during storage at 10 °C were evaluated in terms of colour, pH, polyphenol oxidase (PPO) activity, glucose content and viable cell count. Overall, the combined treatments with organic acids and high pressure conferred the best storage stability of chopped garlic, but the results depended on the physiological state of the raw garlic bulbs. For garlic from dormant bulbs, addition of citric acid rather than ascorbic acid or a mixture of the two inhibited browning more effectively. However, garlic from dormancy‐terminated bulbs, treated with organic acids or high pressure, turned green and then yellowish‐brown or brown. While the PPO activities of chopped garlic treated with organic acids or high hydrostatic pressure were reduced nearly to zero, other possible factors may affect the discolouration of chopped garlic. Concerning microbiological stability, the total viable cells in chopped garlic decreased significantly during storage owing to its own antimicrobial activity and the synergistic effect of high pressure. © 2001 Society of Chemical Industry     

Chemical Changes After Irradiation and Post-Irradiation Storage in Tilapia and Spanish Mackerel

Influence of gamma irradiation (1.5–10 kGy) and post-irradiation storage up to 20 days at 2 ± 2°C on some chemical criteria of tilapia and Spanish mackerel were studied. Total volatile basic nitrogen formation was lower in irradiated fish than in the unirradiated. Irradiation also caused a larger increase in thiobarbituric acid values which continued gradually during storage. Some fatty acids decreased by irradiation treatments at all doses. Thiamin loss was more severe at higher doses (≥4.5 kGy), whereas riboflavin was not affected. Alpha and gamma tocopherols of tilapia and alpha, beta, gamma, and delta tocopherols, in Spanish mackerel, decreased with increased dose and continued to decrease during 20-day post-irradiation storage.     

STORAGE BEHAVIOR of an EARLY GARLIC (ALLIUM SATIVUM L.) SUBJECT to GAMMA-RAY RADIOINHIBITION

Garlic bulbs of an early cultivar (Rosado Paraguayo) were irradiated with a dose of 50 Gy of Co-60 gamma rays at 30 days after harvest. Experimental lots were stored up to 300 days in a commercial warehouse (6-32°C; R.H. 40-50%). the treatment reduced the weight loss of the bulbs and increased the percentage of both marketable bulbs and cloves without affecting organoleptic properties. the results show that both the raw/fresh market for this early cultivar and the garlic processing industry would profit from the radioinhibition process.     

不同颜色蒜泥的风味及挥发性物质分析

以打破休眠期的大蒜为原料,制备白色、蓝色、绿色和黄色4 种颜色蒜泥,采用电子鼻和气相色谱-质谱（gas chromatography-mass spectrometry,GC-MS）联用技术揭示其风味及挥发性物质的变化。电子鼻检测中,不同颜色蒜泥对传感器的响应值雷达图和主成分分析（principal component analysis,PCA）结果显示各个样品间的风味存在显著差异。GC-MS结果显示4 种颜色蒜泥共检测出83 种挥发性物质,其中蒜泥的主要挥发性物质是硫醚类和醛类化合物,此为蒜泥的主要风味物质。使用PCA实现对蒜泥样品挥发性物质的区分,明确4 种蒜泥风味差异的挥发性物质,为研究不同颜色蒜泥的风味差异提供理论依据。     

Investigation of the volatile aroma components of garlic leaves essential oil. Possibility of utilization to enrich garlic bulb oil

The volatile aroma components of Egyptian green garlic leaves essential oil was investigated for the first time. After the utilization of garlic bulbs to prepare garlic oil or after drying the bulbs to produce garlic powder, garlic leaves are considered to be waste material, which is disposed of without any benefit. In this investigation, green garlic leaves were distilled and the essential oil was subjected to GC and GC-MS identification. The yield of the oil was 0.06% (based on wet weight of the leaves). The most prominent compounds of the essential oil were diallyl trisulfide (32.32%), followed by diallyl disulfide (31.35%) and methyl allyl trisulfide (11.40%); these compounds are the same as those found in garlic bulb oil. This means that garlic leaf oil is a rich, renewable and priceless source of garlic aroma compounds which could be utilized in fortification and enriching of garlic bulb essential oil to increase its quantity without changing the quality. Utilization of green garlic leaves for production of essential oil will also save, to some extent, the costs of disposing of large amounts of leaves in garlic possessing factories, transforming them into profits.     

Effects of gamma irradiation and storage temperature on carotenoids and ascorbic acid content of mangoes on ripening

Synthesis and accumulation of carotenoids in the flesh of Alphonso mangoes on ripening was found to be maximal in fruits stored at tropical ambient temperatures (28–32°C). Gamma irradiation of preclimacteric fruits at 25 krad did not affect the formation of carotenoids. Storage of preclimacteric fruits either irradiated or unirradiated at 7–20°C for 16–43 days caused a substantial reduction in carotenoid formation even when these fruits were subsequently ripened under optimal conditions. Regardless of storage temperature, carotenes always exceeded xanthophylls in the ripe fruits and, in general, irradiated fruits showed higher levels of carotenes in comparison with unirradiated samples. Ascorbic acid loss during ripening was maximum at ambient temperatures while lengthy storage at low temperatures caused a net increase in ascorbic acid levels. Irradiation seemed to accentuate the loss in ascorbic acid during ripening.     

Comparison of phenolic acids and flavonoids in black garlic at different thermal processing steps

The phenolic acid and the flavonoid constituents of garlic subjected to different thermal processing steps were examined. Black garlic was produced in a ripening chamber by using a programmed stepwise heating schedule, as follows. Step 1: 90 °C and 100% RH for 34 h; Step 2: 60 °C and 60% RH for 6 h; Step 3: 75 °C and 70% RH for 48 h; Step 4: 70 °C and 60% RH for 60 h; Step 5: 65 °C and 50% RH for 192 h. The results of the present investigations showed that thermal processing affected quantities of each phenolic acid and flavonoid component. The total phenolic content (TPC) and total flavonoid content (TFC) of the garlic subjected to different thermal processing steps were higher than those of fresh garlic. In particular, the black garlic cloves ripened using Step 1 (BG1), black garlic cloves ripened using Step 2 (BG2), black garlic cloves ripened using Step 3 (BG3), and black garlic cloves ripened using Step 5 (BG5) samples exhibited levels of TPC that were higher than the TFC, while the TFC in the fresh garlic (FG) and black garlic cloves ripened using Step 4 (BG4) samples were higher than the TPCs. Hydroxycinnamic acid derivatives were found to be the major phenolic acids of garlic at different processing steps. Among the four major flavonoid subgroups in garlic, flavanols were found at the highest concentrations followed by flavanones and flavones, except in the FG sample.     

Role of precursors on greening in crushed garlic (Allium sativum) bulbs, and its control with freeze-dried onion powder

BACKGROUND: Lachrymatory factor (LF) synthase in onion bulbs reacts with S‐1‐propenyl‐L ‐cysteine sulfoxide (1‐PeCSO), a key compound in garlic greening. In this study, freeze‐dried onion powder containing LF synthase was used in treatments to control garlic greening. Prior to the use of freeze‐dried onion powder to treat greening garlic bulbs, model reactions were conducted to confirm the reactivity of 1‐PeCSO in onion bulbs to garlic greening. RESULTS: While pink pigments were generated from 1‐PeCSO, green pigments were produced from the combination of 1‐PeCSO and S‐2‐propenyl‐L ‐cysteine sulfoxide (2‐PeCSO). However, pigments were formed in the systems containing 1‐PeCSO, amino acid and alliinase. Even non‐greening garlic bulbs stored at 20 °C turned green with the reaction of 200 g L^?1 1‐PeCSO; therefore 1‐PeCSO isolated from onion bulbs had the same role as 1‐PeCSO in garlic bulbs in terms of greening. Onion bulbs turned green after the addition of 600 g L^?1 2‐PeCSO. The addition of freeze‐dried onion powder inhibited garlic greening, and treatment with 15 g kg^?1 onion powder gave the best storage stability of crushed garlic bulbs. CONCLUSION: The addition of freeze‐dried onion powder inhibited the greening in crushed garlic bulbs, and treatment with 15 g kg^?1 onion powder gave the best storage stability of crushed garlic bulbs. Copyright © 2011 Society of Chemical Industry     

Chemical Characteristics and Storage Stability of Pickled Garlic Prepared Using Different Processes

Three processes for preparing peeled pickled garlic were studied: (P) packing directly with an acidified brine, followed by pasteurization (90°C, 8 min); (B) blanching with hot water (90°C, 15 min) before packing, followed by a preservation treatment (pasteurization, preservatives + refrigeration); and (MB) same as B, except that microwave blanching was used (120g garlic cloves, 825W, 1.5 min). All products were microbiologically stable but fructans were hydrolyzed during storage at 27°C. A green pigment was also apparent in (P). Products from (B) or (MB) had better quality than that from (P). Most stable and best quality products resulted from the blanching treatments and water blanching resulted in the product with best color.     

Effect of different drying methods on the volatile components of parsley (<Emphasis Type="Italic">Petroselinum crispum L.</Emphasis>)

The effect of different drying treatments on the volatiles in parsley (Petroselinum crispum L.) was studied. Air drying at ambient temperature resulted in few losses in volatile compounds compared with the fresh herb, whereas oven drying at 45 °C and freeze-drying caused a decrease in the concentrations of the majority of the volatile components, especially those with the greatest impact on parsley aroma: p-mentha-1,3,8-triene and apiole.     

Volatiles in Skin of Low Dose Irradiated Fresh Chicken

Fresh chickens were irradiated with up to 1200 krad at 0–5°C. Volatile compounds from the skin and subcutaneous fat of these chickens, and from unirradiated controls, were analyzed by gas chromatography. Acceptability of the odor of the chickens was also evaluated. Other samples (0 and 300 krad) were evaluated by chemical and sensory analysis after storage at 4°C. Analysis of volatiles indicated that levels of octane, l-octene, hexanal, and nonane increased regularly with radiation dose. Amount of total volatiles was greater in unstored irradiated samples than in controls, but this was reversed after storage. After 14 days, the irradiated sample still had acceptable odor, while the control ahd severely deteriorated.