Effects of post-harvest storage temperature and processing method on glucosinolate hydrolysates, myrosinase activity, and antioxidant capacity in broccoli florets

Aims: Polyscias fruticosa has been well-known as a traditional medicinal herb which shares the same function as ginseng, favorable for their antioxidant capacity. In this study, the herbal health drink had been developed based on the Polyscias fruticosa extract. The effect of preservatives and storage temperature on the total phenolic content, total flavonoid content, and total saponin content were investigated over the period of 16 weeks.
 Methodology: Polyscias fruticosa extract based herbal drinks were formulated. Potassium sorbate and sodium benzoate were used as preservatives while storage temperature was set at 4 and 250C. Determination of total phenolic content was performed by Folin-Ciocalteu method. Meanwhile, analysis of total flavonoid and saponin content was conducted by colorimetric methods.
 Results: In general, the effect of preservatives and storage temperature on the concentration of total phenolic content and total flavonoid content can clearly be seen after 6 weeks, while significant difference in concentration of total saponin content had been evidenced from week 11. Typically, The concentration of total phenolic content, total flavonoid content and total saponin content in formulas added preservatives and kept at 4°C were measured at 2.80±0.26 mg GAE/g, 8.24±0.44 mg CE/g and 20.29±0.27 mg OAE/g after 16 weeks, respectively; however, without adding preservatives and stored at 25°C, these components were found at a value of 1.77±0.1 mg GAE/g, 0.0±0.28 mg CE/g, 14.63±0.59 mg OAE/g, respectively.
 Conclusion: Overall, the presence of preservatives and fridge temperature (4°C) has been the optimal condition to maintain the quantity of biological phytocomponents in herbal health drink; however, the addition of preservatives and storage temperature should be taken into consideration depending on the storage time of herbal drink.

Broccoli is becoming increasingly popular among consumers owing to its nutritional value and rich bioactive compounds, such glucosinolates (GSLs) and hydrolysis products, which are secondary metabolites for plant defense, cancer prevention, and higher antioxidant activity for humans. In this study, 40 μmol/L methyl jasmonate (MeJA) was sprayed onto broccoli from budding until harvest. The harvested broccoli florets, stem, and leaves were used to measure the contents of GSLs, sulforaphane, total phenolics, and flavonoids, as well as myrosinase activity, antioxidant activity, and gene expression involved in GSL biosynthesis. The overall results revealed that GSL biosynthesis and sulforaphane accumulation were most likely induced by exogenous MeJA treatment by upregulating the expression of CYP83A1, SUR1, UGT74B1, and SOT18 genes. Exogenous MeJA treatment more remarkably contributed to the increased GSL biosynthesis in broccoli cultivars with low-level GSL content (Yanxiu) than that with high-level GSLs (Xianglv No.3). Moreover, MeJA treatment had a more remarkable increasing effect in broccoli florets than stem and leaves. Interestingly, total flavonoid content substantially increased in broccoli florets after MeJA treatment, but total phenolics did not. Similarly, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity, trolox-equivalent antioxidant capacity (ABTS), and ferric-reducing antioxidant power (FRAP) were higher in broccoli floret after MeJA treatment. In conclusion, MeJA mediated bioactive compound metabolism, had positive effects on GSL biosynthesis, sulforaphane, and flavonoids accumulation, and showed positive correlation on inducing higher antioxidant activities in broccoli floret. Hence, preharvest supplementation with 40 μM MeJA could be a good way to improve the nutritional value of broccoli florets.

Sulforaphane (SFN) is a health-promoting compound occurring in broccoli. It is formed by action of myrosinase in a two-step reaction that also yields undesirable compounds such as nitriles and isothionitriles. Different techniques affecting enzyme activity and tissue integrity were proposed to increase SFN content in the edible parts and discards of broccoli. Ultrasound processing is an emerging technology that produces these effects in foods, but has been poorly explored in broccoli so far. The aim of this work was to study the effect of ultrasound-assisted blanching on myrosinase activity and SFN content in broccoli florets. Myrosinase showed first-order inactivation kinetics in blanching at different temperatures with and without ultrasound processing. The inactivation rate was faster using ultrasound, with kinetic constants two orders of magnitude higher than without ultrasound. The activation energy (Ea) in traditional blanching (57.3 kJ mol−1) was higher than in ultrasound-assisted blanching (15.8 kJ mol−1). Accordingly, ultrasound accelerates myrosinase inactivation. The blanching time and temperature significantly affected myrosinase activity and SFN content. At 60 °C and 4 min of ultrasound-assisted blanching, myrosinase activity was minimum and SFN content was the highest. These findings may help to design SFN enrichment processes and will contribute to the valorization of agro-industrial wastes.

This study was conducted to determine the effects of postharvest storage temperatures on the antioxidant capacity, anthocyanin compounds, phenolic constituents, and physico-chemical properties of black raspberries. Fresh `MacBlack' berries were stored at 4, 12, 20, and 28 °C for up to 11, 6, 4, and 3 days, respectively. Results showed that higher storage temperatures promoted tissue deterioration (cellular leakage), fungal growth, and moisture loss. The levels of the two major anthocyanins, cyanidin 3-rutinoside and cyanidin 3-xylosylrutinoside, increased by up to 2.7- and 1.9-fold, respectively, with increasing storage temperatures. The antioxidant capacity of berries, as measured by FRAP and ABTS assays, increased by up to 1.5- and 1.4-fold, respectively, which was accompanied by increases in soluble solids, total sugars, total phenolics, and total anthocyanin contents. Our findings indicate that postharvest storage at higher temperatures increases the level of bioactive compounds and antioxidant capacity in black raspberries, but this increase may be due in part to moisture loss and sugar metabolism. Storage at 4 °C maintained the level of bioactive compounds and antioxidant capacity present at harvest and prolonged the effective shelf life of the product. Further studies of black raspberry bioactive components as influenced by postharvest conditions and processing procedures (e.g., IQF, freeze-drying, air-drying) are warranted.

Broccoli is increasing consumed with phytochemicals level. Thermal processing may alter food antioxidant properties by initiating destruction, release or transformation of antioxidant components. Effects of thermal processing methods (boiling, steaming, stir-frying, microwaving, and baking) and duration on antioxidants and total antioxidant capacity (TAC) in broccoli florets have been estimated. Boiling 2 min, steaming 4 min, stir-frying 6 min, microwaving 2 min, and baking 25 min were optimized according to sensory quality evaluation and total ascorbic acids (TAA) retention. Stir-frying resulted in highest total phenolic content (TPC) and total flavonoid content (TFC) with increasing by 47.56 and 67.93%, respectively, followed by boiling (increasing by 28.25 and 44.93%, respectively) and steaming (increasing by 24.90 and 27.49%, respectively). Boiling, steaming, and stir-frying significantly elevated TAC values. Strong positive correlations between TAC and TPC and TFC were found. TAA drastically deteriorated regardless of processing methods. Microwaving and baking displayed destructive effect on broccoli quality. Practical applications Most vegetables have to be thermal processed before eating. It is important to optimize processing methods and duration to promote beneficial effects and to counteract, to the best possible, undesired effects. This study has optimized five common thermal processing methods (boiling, steaming, stir-frying, microwaving, and baking) and duration of broccoli florets. Meanwhile, the effect of these thermal processing methods at defined duration on antioxidants and total antioxidant capacity was estimated. Data obtained are expected to offer both modern food industry and consumers optimum conventional processing methods with the highest nutrients retention in vegetables.

Myrosinase activity on broccoli glucosinolates has been widely and extensively discussed. Purpose Studies on cruciferous vegetables, especially broccoli, have gained significance in the fight against cancer. Glucosinolates in broccoli transformation into sulforaphane occur after its exposure through chewing. However, the relationship between individual chewing patterns linked to denture morphology has not been studied extensively. Research on human digestion has demonstrated how the mechanical breakdown of larger food particles into smaller ones is a crucial precursor to chemical food breakdown. This study is a comparative analysis of how chewing on broccoli tissues by different individuals enables the enzyme myrosinase to break down broccoli glucosinolates chemically. Individual chewing patterns linked to the surface anatomy of the pre-molars and molars and the myrosinase activity on broccoli glucosinolates will be investigated. Methods Three individuals chew a 4-millimeter broccoli floret four times sequentially into a four-millimeter-long broccoli floret (2 grams), and the floret length was measured at each bite until the sample was ground. Then the chewed broccoli was combined with distilled water, filtered, and myrosinase activity was measured using photospectrometric measurements and an agar diffusion test. Human pre-molars and molars are measured in millimeters. Results Data from the three human chewing mechanisms compared to the mechanical breakdown performed by an automatic mixer shows different values and is individually specific. Conclusion Individual chewing patterns link to the unique surface anatomy of the pre-molars and molars, subsequently impacting the myrosinase activity on broccoli glucosinolates’ breakdown individually.

The present investigation aimed to enhance the postharvest shelf-life of broccoli using vacuum impregnation (VI). Broccoli florets were impregnated with physiologically active chemicals, i.e. calcium chloride and ascorbic acid. Post-impregnation broccoli florets were packed in three different packaging materials (poly(ethylene terephthalate) punnets, low-density polyethylene pouches and shrink-wrap film) and stored at two temperatures (5 and 25 °C). The effects of impregnation solutions, packaging materials and storage temperature on physicochemical attributes (weight loss, total soluble solids, ascorbic acid, total chlorophylls and carotenoid content), antioxidant and phenolic contents, and shelf life were studied. The changes in the chemical structure post-impregnation and during storage were investigated using Fourier transform infrared (FTIR) spectroscopy. Results showed that impregnated broccoli florets exhibited significantly (P < 0.05) higher levels of biochemical attributes immediately after impregnation. During storage, the physicochemical and antioxidant properties of broccoli florets declined for all the samples. However, the reduction in these properties was significantly (P < 0.05) lower in impregnated florets as compared to untreated control samples. Principal component analysis and FTIR results also indicated a clear difference in the impregnated and control samples. The shelf-life of broccoli florets stored at 25 °C was assessed as 4 and 3 days for impregnated and control samples, respectively; whereas the samples stored at 5 °C had a shelf-life of 12 days for impregnated samples and 5 days for the control samples. The findings of the study elucidate the potential of VI in enhancing the initial quality and shelf-life of broccoli. The deterioration during storage is primarily due to physiological weight loss, a natural loss of water and volatile compounds that occur following harvest due to transpiration and respiration. Excessive transpiration can lead to dehydration, which reduces the quality and shelf-life of the product. © 2024 Society of Chemical Industry.

PurposeA healthy and easy-to-use orange snack obtained from the freeze-dried orange pulp puree is proposed. Once the commercial packaging of the snack has been opened, the effect of conventional home storage temperature on its physicochemical properties and on the content of bioactive compounds has been studied. This research aims to recommend the consumer, and therefore the manufacturer, the best conditions for home storage of this product, keeping its nutritional quality and antioxidant capacity, as well as maintaining its colour and crispness.Design/methodology/approachThe water content, water activity, hygroscopicity, crispness, colour, vitamin C, β-carotene, total phenolic compounds and antioxidant activity were characterised both when the orange snack was newly obtained and after one, two and six months of storage inside zipper bags, at 4 and 20 ºC.FindingsThe results indicated that, in these conditions, the orange snack increased its water content, causing a loss in both its porosity and its characteristic crispness. Nevertheless, the bioactive compounds remained stable throughout the storage period, with the exception of β-carotene, the content of which decreased markedly when the orange snack was stored at 20 ºC.Originality/valueFew studies have evaluated the stability of food products during home storage. The findings showed that the maximum storage time to ensure a proper texture of the orange snack studied is between two and six months, both at 4 and 20 ºC. However, from the point of view of the conservation of both vitamin C and, especially, of β-carotene, it is recommended that this product be stored in refrigeration.

The influence of two Spanish growing locations with well-differentiated climatic conditions (northern and eastern areas) on the main bioactive compounds, glucosinolates (GLS), total phenolic compounds (TPC), and vitamin C, as well as myrosinase activity and antioxidant capacity in five white cabbage ( Brassica oleracea L. var. capitata) cultivars was investigated. Cabbages with the highest concentration of total GLS presented the highest vitamin C level (r = 0.75, P ≤ 0.05) and the lowest antioxidant capacity (r = -0.76, P ≤ 0.05). The cultivars with the highest vitamin C content had the lowest myrosinase activity (r = -0.89, P ≤ 0.05) and antioxidant capacity (r = -0.86, P ≤ 0.05), whereas those with the largest TPC amount showed the highest antioxidant capacity (r = 0.71, P ≤ 0.05). Cabbage cultivars grown in the northern area of Spain with low temperatures and radiation led to higher mean values of myrosinase activity (29.25 U/g dm), TPC (10.0 GAE mg/g dm), and antioxidant capacity (81.6 μmol Trolox/g dm), whereas cultivars grown in the eastern area with high temperature and radiation led to larger mean values of GLS (14.3 μmol/g dm) and vitamin C (5.3 mg/g dm). The results of this investigation provide information regarding the most suitable Spanish growing location to produce white cabbage with an optimized content of health-promoting compounds.

Effect of storage time and temperature on the viability of E. coli O157:H7, Salmonella spp., Listeria innocua, Staphylococcus aureus, and Clostridium sporogenes vegetative cells and spores in vacuum-packed canned pasteurized milk cheese

Influence of hormetic heat treatment on quality and phytochemical compounds of broccoli florets during storage

Heating decreases epithiospecifier protein activity and increases sulforaphane formation in broccoli

Heating decreases epithiospecifier protein activity and increases sulforaphane formation in broccoli

Optimization of a blanching step to maximize sulforaphane synthesis in broccoli florets

Effect of storage temperature on crystal formation rate and growth rate of calcium lactate crystals on smoked Cheddar cheeses