Allium sativum L. (Garlic) bulb enlargement as influenced by differential combinations of photoperiod and temperature.

Photoperiod and temperature are vital environmental factors that regulate plant developmental processes. However, the roles of these factors in garlic bulb enlargement are unclear. In this report, responses of garlic bulb morphology and physiology to combinations of photoperiod (light/dark: 10/14 h, 12/12 h, 14/10 h) and temperature (light/dark: 25/18 °C, 30/20 °C) were investigated. For garlic cultivar G103, bulb characteristics, phytohormones (IAA, ABA, ZT, tZR, JA), allicin and phenolic acids (p-coumaric and p-hydroxybenzoic) were highest under a photoperiod of 14 h at 30 °C. Maximum GA was observed under 14 h + 30 °C for cv. G2011-5. Maximum caffeic, ferulic and vanillic acids were detected for cv. G2011-5 at 14 h + 30 °C, 12 h + 25 °C and 14 h + 25 °C, respectively. Flavonoids (myricetin, quercetin, kaempferol and apigenin) were not detected in this trial. This is the first report describing the impact of long periods of light duration and higher temperatures on garlic morphology, phytohormones, phenolic acids and allicin content.

Influence of illumination on the greening and relative enzyme activity of garlic puree.

Garlic has attracted considerable attention because of its bactericidal and anticancer effects. However, the greening of garlic purees greatly affects the product quality. This study investigated the influence of light colors and power on the greening of garlic, and determined the key substances of garlic puree greening, including γ-glutamyl transpeptidase (γ-GT), thiosulfinate, and alliinase. Results showed that purple light source greatly affects greening power, γ-GT, and thiosulfinate. Illumination using a 3-W power lamp could reduce the production of thiosulfinate and alliinase and inhibit the green transformation reaction. Illumination using a 5-W power lamp greatly affected the thiosulfinate content and greening power, whereas that using a 7-W power lamp greatly influenced the γ-GT activity, porphobilinogen content, and alliinase content. Results showed that the green color of garlic puree is greatly affected by the illumination color and intensity, which provides theoretical support for the anti-greening of light garlic puree. PRACTICAL APPLICATION: Because garlic puree easily turns green during processing, which affects the product quality and economic value, this study uses controllable light source radiation to influence the greening of garlic puree, hoping to delay or even solve this problem and provide a new simple method to prevent garlic puree from turning greening.

Effect of different light spectra on the pigmentation of stored elephant garlic.

BACKGROUND: In the present study high-brightness light-emitting diodes were used to investigate the influence of different light spectra on garlic discoloration at different humidity levels and temperature. Many processes involved in the discoloration process of garlic/leek during storage under different conditions remain unanswered. For this reason in this study the ability of specific light spectra to enhance the production of desirable pigments has been evaluated in elephant garlic. It is well known that the pigments involved in the discoloration reaction are of great interest because of their potential ability to increase the nutritional value and health benefits of the food. RESULTS: In the present study, we show how the chlorophyll content of the sprout increases directly proportionally to the wavelength of the light tested; green/blue light delays the greening process of garlic young shoots whilst red/infra-red light irradiance conditions increase the greening process at different storage temperatures and humidity. Moreover different lights in the visible spectrum have been observed to stimulate and enhance the outer layer purple coloration. CONCLUSION: The use of different lights to modulate garlic pigmentation has been demonstrated and, in particular, the utilisation of red/green/blue lights and lower temperature resulted in higher red/pink pigments production supporting the hypothesis that this process involves more than one light to be fully performed and the low temperature is a condition that influences the formation of these products. © 2017 Society of Chemical Industry.

Physical-, chemical-, and microbiological-based identification of electron beam- and γ-irradiated frozen crushed garlic.

Identification of frozen crushed garlic, commercially available in the Korean market, was performed using four different analytical techniques (three screening and one confirmation). The garlic samples produced in Korea and China were irradiated (electron-beam and γ-rays) at 0, 1, 4, and 7 kGy. Non-irradiated samples showed a relatively moderate population of aerobic bacteria and yeasts/molds around 10(5) CFU/g. Irradiation treatments unequivocally reduced the microbial/fungal populations with dose increments. Microbiological screening through direct epifluorescent filter technique/aerobic plate count (DEFT/APC) method effectively differentiated the non-irradiated and irradiated samples. An electronic nose method positively differentiated the odor patterns of samples based on chemical sensing. However, photostimulated luminescence technique (PSL) exhibited poor sensitivity. Minerals separated from irradiated samples produced thermoluminescence (TL) glow curves in the specific temperature range of 150-250 °C. In conclusion, TL confirmatory analysis gave the most promising results in detecting the irradiation status of garlic samples irrespective of the production origin and type of ionizing radiation treatment.

Identification of a gamma-irradiated ingredient (garlic powder) in Korean barbeque sauce by thermoluminescence analysis.

UNLABELLED: Thermoluminescence (TL) analysis was applied to identify gamma-irradiated garlic powder in Korean barbeque sauce before and after pasteurization (85 °C, 30 min), when blended in different ratios (1%, 3%, and 5%). The sauce sample with nonirradiated garlic powder gave a background glow curve. However, the sample blended with irradiated ingredient (1 and 10 kGy) showed typical TL glow curves at temperatures of 150 to 200 °C. The identification properties of sauce samples were more influenced by blending ratios than by irradiation doses, showing that 3% and 5% added samples produced glow curves at 150 to 250 °C. After pasteurization of the samples containing the irradiated ingredient, TL glow intensity decreased but did not change its shape or temperature range. As a result, the pasteurization of Barbeque sauces containing irradiated ingredients had reduced TL glow intensity, but the shape and temperature range of glow curve were still able to provide information required for confirming irradiation treatment. PRACTICAL APPLICATION: To monitor the irradiated food in international market, thermoluminescence (TL) analysis is considered most promising identification technique because of its sensitivity and long-term stability. In this study the applicability of TL analysis to detect an irradiated ingredient (garlic powder) added in low quantity to a food matrix (sauce) was investigated. The effect of processing (pasteurization) on TL results was also evaluated.

Comparison of distillation and ultrasound-assisted extraction methods for the isolation of sensitive aroma compounds from garlic (Allium sativum).

A comparative study of traditional simultaneous distillation extraction (SDE), microwave assisted hydrodistillation extraction (MWHD) and ultrasound-assisted extraction (USE) is presented, for the extraction of essential oils from fresh garlic (Allium sativum) cloves. Each method is evaluated in terms of qualitative and quantitative composition of the isolated essential oil. The highly reactive sulfur molecules of the garlic volatile fraction show variable response to the different isolation methods. The application of ultrasound for the extraction of the essential oil is considered to cause a lesser damage of thermal-sensitive molecules, thus, providing a better approach of the compounds primarily responsible for the characteristic odor and taste of freshly chopped garlic. All heat-involving isolation procedures have been shown to differentiate the volatile-fraction profile as analyzed by GC-MS. Especially when grouping the compounds into cyclic and acyclic, the percentage concentrations drop from 77.4% to 8.7% for the acyclic while that of the cyclic compounds increase from 4.7% to 70.8%. The observed fact may be attributed to the effect of the heat applied, which changes from harsh thermal treatment (SDE) to short time thermal (MWHD) and room-temperature isolation (USE). The use of USE proves to be crucial in order to provide reliable insight into garlic's chemistry.

Allixin induction and accumulation by light irradiation.

Allixin, a phytoalexin isolated from garlic, was induced by irradiating fresh garlic cloves with sunlight or UV light. Induced allixin was analyzed by HPLC, and the accumulated amounts of allixin were 3.1-6.3 microg/g under experimental conditions.

Effects of gamma irradiation on the flavor composition of food commodities.

Fifteen food products including potato, sweet potato, shallot, onion, garlic, ginger, papaya, mango, rice, tobacco, small red bean, mungbean, soybean, wheat, flour and spices have been approved for irradiation by the National Health Administration in Taiwan. Market tests (Wu et al., 1996) provided strong proof that Taiwanese consumers would accept irradiated foods. However, researchers in the food industry are concerned about the possibility of chemical changes, especially in volatile composition, during irradiation processing. This study considers several food commodities, including garlic, ginger, shiitake, onion, potato, day-lily, tilapia, silver carp and shrimp. Food samples were irradiated with optimum doses and then studied for possible occurrence of chemical changes and effects on compositional characteristics of foods.

Biochemical changes in garlic (Allium sativum L.) during storage following gamma-irradiation.

The aim of this paper was to evaluate an acute dose of gamma-rays (10 Gy) on post-dormant garlic seed cloves in terms of total DNA, total RNA, total protein and soluble carbohydrates in order to correlate these levels with sprouting inhibition induced by gamma-irradiation. Decreases in total DNA content were found in inner sprouts immediately and 100 days after irradiation. The total RNA and protein contents and the carbohydrate content of the storage leaf or the inner sprout were not affected by gamma-irradiation. The results support the notion that in post-dormant garlic seed cloves, DNA content and its behaviour seem to be among the sensitive cellular responses to radiation.

Changes in peroxidases associated with radiation-induced sprout inhibition in garlic (Allium satiyum L.).

The effects of an acute dose of gamma-rays (10 Gy) to post-dormant garlic cloves on inner sprout growth and changes in peroxidases and soluble proteins were evaluated up to 100 days of storage in darkness at 19 +/- 1 degree C and 42 +/- 2% relative humidity. Radiation-induced inhibition of sprout growth became evident after 25 days of treatment and was synchronous with a marked increase in peroxidase activity. Thin-layer isoelectric focusing revealed that radiation induced an increase in the number of anodic peroxidase isoenzymes at 100 days, suggesting modifications in the vascularization process. Neither the soluble protein content nor the protein pattern were affected by irradiation. These results are discussed in terms of a possible mediating effect of peroxidase on radiation-induced sprout inhibition in garlic.