Blanched Samples Research Articles

Effects of vacuum and multiflash drying on the microbiota and colour of dried yellow mealworm (Tenebrio molitor)

Larvae ofTenebrio molitor (yellow mealworm; YM) are an alternative to conventional animal protein as food and feed thanks to their high nutritional value and low environmental impact for production. Since some studies have reported high water activity (aw ) with different microbial contamination levels, blanching and drying can be employed to reduce microbial load, enzymatic activity, moisture content, and water activity, ensuring safety and preserving YM for longer periods. This study applied rinsing or blanching followed by vacuum- or multiflash drying, aiming to preserve YM by reducingaw and the microbial load, enabling its use as food and feed. The processing impact on YM colour was evaluated, and they were also subjected to anEscherichia coli contaminated wheat bran to perform a challenge test to evaluate the effectiveness of the decontamination. Drying curves were determined for each situation. Multiflash drying procedure was faster than vacuum drying for reducing YM moisture. Additionally, blanched samples required a shorter period to reach the targeted water activity (0.2-0.3) than rinsed samples. Blanching plus vacuum drying reduced more than 5 logE. coli load in YM in the challenge test. Vacuum drying preserved YM brightness the most. In conclusion, this study showed that drying could provide shelf-stable YM. Besides, only 15 s of blanching before drying gives better brightness and leads to a greater microbial reduction after a relatively short drying time.

Effect of Drying Temperature on Physiochemical Properties of Powder from Blanched and Unblanched Lemon Peel and Sensory Quality Evaluation of the Powder Fortified Biscuits

Preparation of biscuit incorporating lemon peel powder can be a new approach in formulating fortified fast food. This investigation was made to evaluate quality of prepared biscuits with lemon peel powder. The effect of temperature on drying time and physiochemical properties of lemon peel powder and their effects on biscuits were also examined. Two drying temperatures (650C and 750C) were employed for both blanched and unblanched lemon peel. The formulated biscuit samples incorporating 1 % lemon peel powder were compared with control biscuits which were prepared with 100% wheat flour. It took longer time (18 hr) for drying of blanched sample at 65 0C whereas shorter time (8 hr) was required for that of blanched sample at 750C. There was a significant decrease in the physiochemical properties of lemon peel powder with the increase of temperature except protein and fibre content. In addition, moisture content of the unblanched sample was found to be lower than the blanched sample at the same temperature. Significantly higher ascorbic acid was obtained by the unblanched samples. Protein and fibre content for both unblanched and blanched sample at the same temperature were found to be higher. All the samples were significantly different at 5% level of significance for overall acceptability. Biscuits prepared with unblanched dried lemon peel powder (at 650C) sample secured the highest score in case of all the sensory parameters. Therefore, quality fortified biscuit can be prepared commercially by incorporating 1 % lemon peel powder in wheat flour for the fast food consumer.

Impact of blanching and packaging materials on postharvest quality and storability of fresh spinach

Spinach is a widely consumed leafy green vegetable, but it exhibits short storage life due to quick loss in moisture contents during postharvest period. The present study was aimed to evaluate the effect of blanching treatment and different types of packaging on spinach quality under cold storage conditions. Fresh spinach after treatment [T0 = control, T1 = blanching, T2 = modified atmosphere packaging (MAP-1, Xtend®), T3 = MAP-2 (Bio-fresh®) and T4 = perforated polyethylene (PE)] application was stored at 4±1 °C and 90±5 % RH for 20 days. Samples were analyzed at the time of harvest (0 day) and then after 3 days interval during storage. MAP treatments performed well and had a positive effect on spinach by maintaining its freshness and quality. Decay, ion leakage and weight loss were observed lower in spinach packed in MAP-1(Xtend®) followed by MAP-2 (Bio-Fresh®) and perforated PE packaging. MA packaging maintained higher ascorbic acid content, chlorophyll, and total antioxidants of spinach during storage. Nevertheless, spinach packed in perforated PE also displayed better results in maintaining quality as compared to control and blanched samples. The maximum weight loss, poor quality, minimum ascorbic acid content with lower consumer acceptability was recorded in control samples. Overall, MAP-1(Xtend®) could be used as a promising technology to maintain the quality of spinach up to 20 days of cold storage.

Changes in Phenolic Metabolites and Biological Activities of Pumpkin Leaves (Cucurbita moschata Duchesne ex Poir.) During Blanching.

Pumpkin leaves (Cucurbita moschata Duchesne ex Poir.) are popularly consumed in Sub-Saharan Africa and Asia. Blanching the leaves before drying is a method of preservation during off-season. In this study, different blanching treatments and media are used to test the changes in non-targeted phenolic compounds, antioxidant capacity (FRAP and ABTS activity), in vitro α-glucosidase activity and cell cytotoxicity of pumpkin leaves. Steam blanching in plain water led to the highest retention of total phenolic content and reduced the loss of quercetin 3-glucoside 7-rhamnoside (Rutin), kaempferol 7-neohesperidoside, isoorientin 2″-O-rhamnoside, isorhamnetin-3-O-rutinoside, quercetin 3-galactoside, coumaroyl glucaric acid, isorhamnetin-3-galactoside-6″-rhamnoside, 2-caffeoylisocitric acid, quercetin 3-galactoside 7-rhamnoside by (3.04%), (7.37%), (10.65%), (10.97%), (14.88%), (16.1%), (16.73%), (18.88%), and (23.15%), respectively, and coumaroyl isocitrate increased by 14.92%. Candidate markers, 2-O-caffeoylglucaric acid, 2-(E)-O-feruloyl-D-galactaric acid, quercetin 3-galactoside 7-rhamnoside (rutin) and unidentified compounds ([(M-H) 677.28 and at RT 21.78] were responsible for the separation of the steam blanched samples in plain water from the other blanching treatments. Steam blanching in plain water increased the antioxidant capacity (FRAP and ABTS activity). There were no cytotoxic effect or inhibitory effect of α-glucosidase activity detected in the raw or blanched pumpkin leaves. Thus, this study recommends steam blanching in plain water for African cuisine, and confirms it is safe to consume pumpkin leaves frequently.

EFFECT OF ULTRASOUND AND ACID PRETREATMENTS DURING DEHYDRATION ON QUALITY PROPERTIES OF QUINCE

Several methods are employed to remove the moisture from organic or non-organic materials, in a variety of industrial applications. Among all, dehydration of fruits is an alternative to decline post-harvest loss of fruits and also a process to produce dried fruits, which can be directly consumed or become part of foodstuffs like cakes, and many others. In particular, drying provokes a series of changes in materials, such as oxidation, browning, or loss of nutritional-functional properties. Ultrasound is famous to have a significant effect on the rate of various processes. Quince is a fruit which is rich in polyphenols, organic acids, and amino acids with important health benefits. The present study examined the effect of ultrasound and blanching pre- treatments prior to convective drying on quality properties of dehydrated quince slices. A completely randomized design was used to address the effect of time of sonication (10−30 min), temperature (40−60°C), and anti-browning agents including acetic, citric, and ascorbic acids as well as distilled water on quality properties of dehydrated quince slices. The obtained results revealed that the shortest drying time (270.33±35.59 min) and the highest total phenolic content (57.29±12.72 mg GAE/ml) were recorded for samples exposed to the ascorbic acid solution. Comparison of the pre-treated and control samples indicated that the highest rehydration ratio (2.75±0.29 %) was achieved by blanched samples in acetic acid solution. The use of citric acid solution led to the highest score in the taste (3.45±1.1), color (3.84±0.9), and texture (3.47±1.02) of quince slices on the basis of a 5- point hedonic scale. The obtained results depended on both ultrasound and the type of blanching solution. Citric and acetic acid samples indicated the highest values of the sensory evaluation and water loss, respectively.

High humidity air-impingement blanching (HHAIB) improves drying characteristics and quality of ground-cover chrysanthemum heads

Abstract Effects of high humidity air-impingement blanching (HHAIB) temperature, relative humidity over a range of application time and drying temperature on air-impingement drying kinetics, colour attributes, browning index, blanching weight loss and total flavonoids content of chrysanthemum heads were studied. HHAIB could shorten the drying time of chrysanthemum heads significantly (p < 0.05) by up to 52% compared to the control group without blanching. Meanwhile blanching humidity has a greater influence on drying kinetic than other blanching parameters. D eff values of samples declined first and rose later with the growth of blanching humidity, while increased continuously with the growth of blanching temperature. The highest growth of total flavonoids content can be up to 21.6% under the HHAIB blanching conditions (110 °C of blanching temperature, 45% of relative humidity, 150 s of blanching time) in comparison with the control group. Lightness of all blanched samples was lower than the control group, and redness and total colour difference under different blanching conditions showed significant differences compared to the control group, while no obvious variation was observed in terms of yellowness values.

High pressure and thermal processing on the quality of zucchini slices

In response to the market demand for low processed vegetables, high-pressure treatments (400,600 MPa; 1,5 min) were applied on zucchini slices and compared to a traditional blanching treatment. Histological observations, texture and color analysis, pectinmethylesterase (PME) and antioxidant (DPPH) activities were measured and compared to untreated samples. The histological observations revealed that the longer high-pressure treatments (5 min) led to more extended cell lysis and dehydration than the shorter ones (1 min) and blanching. High-pressure treatments resulted less effective than blanching on PME inactivation, with the best results obtained at 400 MPa for 1 min. Comparable texture parameters were observed for high-pressured and blanched samples. The negative correlation found between PME activity and the texture parameter ‘distance of the first peak force’ revealed an effect of PME on the texture recovery after treatments. High pressure led to a general browning of zucchini parenchyma and to DPPH drop. The correlations found between DPPH and color suggest the common nature of the phenomena. The influence of pressure and time on the studied parameters was revealed by two-way ANOVA. Principal component analysis clustered together the four high-pressure-treated samples, being clearly divided by blanched and untreated ones.

Effect of pretreatment on physicochemical, microbiological, and aflatoxin quality of solar sliced dried ginger (Zingiber officinale Roscoe) rhizome.

Pretreatment of fruit and vegetables is necessary to reduce microbial proliferation and to preserve color of the produce. The effect of drying and pretreatment with potassium metabisulfite (KMBS) of concentrations 0.0%, 0.1%, 0.15%, 0.2%, and 1.0% and blanching at 100°C and 50°C using a tent‐like concrete solar (CSD) dryer as compared to open‐sun drying (OSD) of yellow ginger rhizomes was investigated using routine methods. The total color change and residual sulfur dioxide (SO2) were analyzed. KMBS reduced the yeast and mould load significantly from 3.6 × 104 ± 1.4 × 103 CFU/g in 0.0% (control) to <10 CFU/g in 1.0% KMBS and 100°C blanched fresh samples. Drying of the fresh samples for 5 days increased the yeast and mould load of all the treatments to as high as 1.15 × 105 ± 2.12 × 104 CFU/g for the 1.0% KMBS. Overall, the CSD had fewer microbial loads than the OSD but it was not significant. Aflatoxins and Salmonella sp. were not detected in any of the samples. The sulfur dioxide residue (SO2) for KMBS pretreated samples increased as the concentration of KMBS increased with the CSD retaining slightly higher amount than the OSD. The total color change index increased with increase in KMBS, and drying further increased the total color change index. On the whole, the blanched samples had the least color change among the pretreatments with 100°C CSD showing the least change among the dried samples.

Development of Instant Chutney Powder with Incorporation of Blanched Carrot and Green Leafy Vegetable Powders

Instant chutney powder, a palatable functional food adjunct, was developed by using carrot (Daucus carota L), basella (Basella alba L) and spinach (Spinacia oleracea) leaves and other selected spice ingredients. The carrot, basella and spinach were blanched for 1 to 3 minutes and dried. The dried powders were subjected to assessment of colour parameters to standardize the time period for blanching. The Hunter (a*) values of blanched samples became more positive, indicating that those samples were greener and intensity of greenness was more in samples blanched for 3min. Hunter (a*) values of carrot were significantly lower (P &lt; 0.05) for blanched samples than for unbalanced samples which show the intensity of carotenoids. The dried carrot, basella and spinach powders were added to standard chutney powder in different ratios and subjected to sensory evaluation. The best combination which selected was CACP4 (Carrot: basella: spinach-1:1:2). It was noted that the combination of vegetable with greens were accepted better rather than only standard powder.

Effects of vacuum-steam pulsed blanching on drying kinetics, colour, phytochemical contents, antioxidant capacity of carrot and the mechanism of carrot quality changes revealed by texture, microstructure and ultrastructure

An emerging blanching technology, namely vacuum-steam pulsed blanching (VSPB) was employed to blanch the carrots and its effects on blanching efficiency, microstructure and ultrastructure, drying kinetics, colour, texture, phytochemicals (phenolics and β-carotene) and antioxidant capacity of carrot slices were explored and compared with the traditional hot water blanching. Results showed that both blanching treatments enhanced the drying velocity and shortened the drying time by 25.9% compared with untreated samples. VSPB yielded higher blanching efficiency, better colour (more red and yellow), greater antioxidant capacity and higher preservation of phytochemicals compared with hot water blanched samples. Especially, compared to hot water blanched carrots, the p-hydroxybenzoic acid, ferulic acid, and caffeic acid content of VSPB samples increased of 106.6%, 42.0%, and 19.0%, respectively. Interestingly, the chlorogenic acid content in the blanched carrot increased more than 220 times compared to fresh samples. Ultrastructure and microstructure observation clarify the mechanism of quality enhancement of VSPB.

Mathematical Modelling of Blanch-Assisted Drying of Pomegranate (Punica granatum) Arils in a Hot-Air Drier

The effect of blanching conditions on the hot-air drying kinetics of three pomegranates (cvs. “Acco”, “Herskawitz” and “Wonderful”) were assessed. Water blanching conditions considered were 90 °C for 30 s, 90 °C for 60 s, 100 °C for 30 s and 100 °C for 60 s. The drying experiments were carried out at 60 °C, 19.6% relative humidity and at a constant air velocity of 1.0 m s−1. The experimental curves were fitted to seven different drying models. For the Acco cultivar, the drying behaviour was best predicted by the Logarithmic and Page model for blanched (R2 ranging between 0.9966 and 0.9989) and unblanched (R2 = 0.9918) samples, respectively. Furthermore, for the Herskawitz cultivar, Logarithm, Page and Midili models were most suitable for predicting drying behaviour of both blanched and unblanched samples. Also, for the Wonderful cultivar, Logarithm and Midili models were most accurate for predicting the drying behaviour for both blanched and unblanched samples amongst other models. The blanched samples dried faster with shorter drying times: “Acco” (7 h), “Herskawitz” (8 h), and “Wonderful” (7 h), compared to the unblanched samples, which dried after 15, 20 and 11 h, respectively. Effective diffusion coefficient of moisture in pomegranate arils ranged from 4.81 × 10−9 and 1.11 × 10−8 m2 s−1 for the Acco cultivar, for the Herskawitz cultivar; 3.29 × 10−9 and 1.01 × 10−8 m2 s−1 and for the Wonderful cultivar; 5.83 × 10−9 and 1.09 × 10−8 m2 s−1. Overall, blanching resulted in low energy consumption during drying of pomegranate arils. In addition, the Logarithmic model generally showed an appropriate model for blanched samples regardless of cultivar. For unblanched samples, the Page model was more appropriate for “Acco” and “Herskawitz”, while the Midili model was appropriate for “Wonderful”. Therefore, this study provided science-based and practical drying conditions for the investigated pomegranate cultivars.

Effect of air drying on quality characteristics and mass transfer kinetics of osmotically dehydrated sea buckthorn by stevia

Sea buckthorn is ranked among the most significant super foods worldwide. Its fruits and leaves are used as fresh or dried in food, pharmaceutical and cosmetic industry. As super food any pre-treatment should sustain this property and hence this research was focused on osmotic dehydration of sea buckthorn by stevia also a super food. Therefore, water loss, sugar gain, acidity, ascorbic acid and water diffusivity were evaluated during osmotic dehydration of sea buckthorn by two stevia solutions, 15ο and 30οBrix and following were air-dried at 50οC by comparing the effect of steam blanching per case. Steam blanched samples exhibited increased water loss at the end of the process, 55% at 30οBrix and 48% at 15οBrix, compared to untreated samples where losses were 43% (30οBrix) and 28% (15οBrix) respectively. Ascorbic acid was significantly reduced, exceeding 50% in steam blanched samples and 23% in untreated samples. Steam blanched samples dehydrated at 15oBrix exhibited 82% dry matter increase and only 39% the untreated samples. Similarly, samples dehydrated at 30oBrix exhibited 84% dry matter increase and 53% when no steam blanching was applied. Solid gain was seven times less compared to water loss which is attributed to high molecular weight of steviol glycoside. The osmotic dehydration and airdrying curves were described effectively by Peleg and Fick models, and Logarithmic and Fick models respectively, having in all cases R2 adj&gt;99% and SEE&lt;0.2. The water diffusivity of steam blanched samples was 3.2-5.57×10-11 m 2 /s for water loss and 1.27- 2.03×10-11 m 2 /s for solid gain at 30oBrix and 2.12-4.27×10-11 m 2 /s and 0.91-1.98×10-11 m 2 /s at 15oBrix. Finally, the water diffusivity of steam blanched samples during air-drying was 2.11-2.29×10-11 m 2 /s and 1.56-1.66×10-11 m 2 /s in the case of untreated samples.

Microstructures and Elemental Distribution of Magnetic Field Pre-Treated Fluted Pumpkin Leaf

Abstract There is a scarcity of studies on the use of magnetic field for food pretreatment, especially in relation to a knowledge on the pretreatment at the level of microstructures and elemental distribution of food. Therefore, the effect of magnetic field pretreatment on the microstructures and elemental distribution (Na, K, Ca, Mg and Fe) of fluted pumpkin leaf was studied. Three types of magnetic field (static, pulse and alternating) in combination with varying magnetic field strength (5–30 mT) and pretreatment time (5–25 min) were used as variable factors. Fresh (untreated) and blanched samples were used for experiment control. After the pretreatment, all samples were dried at 50 °C and analysed in terms of microstructure and elemental distribution using scanning electron machine. Results showed that fresh and blanched samples of fluted pumpkin leaf exhibited microstructural features that were clearly different from samples pretreated by magnetic field. Pretreated samples showed contents of: 1.3–4.35% sodium; 1.20–3.42% potassium; 1.19–6.10% calcium; 0–5.10% magnesium and 1.22–6.62% iron. Changes in microstructures of samples caused by magnetic field pretreatment led consequently to better retention/improvement in elemental distribution in contrast to blanched and fresh samples in majority of cases.

Effect of Steam Blanching, Dehydration Temperature & Time, on the Sensory and Nutritional Properties of a Herbal Tea Developed from Moringa oleifera Leaves.

The core purpose of the current study is to explore the use of Moringa oleifera leaves, to produce a herbal tea with acceptable sensory properties and nutritional properties by utilizing the steam blanching technique, different dehydration temperatures and time, which can be accepted in the Sri Lankan market. Six sets of samples were prepared where temperature and time combinations were 55°C—6 h, 60°C—4.30 h, 65°C—3 h for the unblanched samples & 55°C—6 h, 60°C—5.30 h & 65°C—4 h for the steam blanched samples. These samples were evaluated, employing a trained panel of 5 tea tasters and a semi trained panel of 35 members. The sample code 706 (steam blanched, 65°C—4 h) was selected as the sample with best sensory attributes. The blanched and unblanched samples dried at 65°C were tested for their proximate, mineral, vitamin, antioxidant and phytochemical contents. The effects of steam blanching on these two samples were evaluated & compared. This study highlights that steam blanching significantly increased the carbohydrates, fat, Mn, Fe, vitamin A, vitamin E and the DPPH scavenging activity whereas steam blanching significantly reduced the protein, fiber, Na, K, Ca, Total phenolic contents and flavonoids content but vitamin C, Zn, Cu and Mg contents were unaffected by steam blanching.

Effect of Blanching Media on the Yield Stress of Green Leafy Vegetable Puree

This study was carried out to determine the effect of different blanching media on the rheological value (yield stress) of two indigenous leafy vegetables, Ipomea aquatic and Basella alba puree. They were blanched using three different blanching media (NaCl, MgO, and NaCl+MgO) for 3 minutes at a temperature of 900C. The yield stress of vegetable puree (3.50Brix) was investigated by varying shear rate from 0.1 to 100/s at different temperatures (278K and 358K) for both unblanched and blanched samples (with media). Measurements and calculations of the different yield stress of puree were performed by MCR-102 and Casson model respectively. The blanch samples were generally of higher yield stress than the unblanched samples with respect to blanching media and temperature. One-way ANOVA indicated a significant difference in yield stress between the two vegetables across the various blanching media (p&lt;0.05). Basella alba had an overall higher yield stress value than another leafy vegetable with respect to different blanching media and temperatures.

Effect of Blanching and Drying Temperatures on Various Physico-chemical Characteristics of Green Beans

Fresh green bean samples (un-blanched and blanched) were dried at 50, 60 and 70 °C, followed by studying the effect of blanching treatment and drying temperature in various characteristics and storage study in HDPE and LDPE packaging material. The blanched dried green bean samples showed lower ash content but higher rehydration ratio, chlorophyll content and carbohydrate content than un-blanched dried green bean samples. No significant change in moisture, protein, fat and fibre content was observed after blanching. The green beans were dried up to the moisture content of 14±0.5 from an initial moisture content of &gt; 90 %. The increase in the drying temperature reduced the drying time. Blanching treatment enhanced the drying rate, the kinetics parameter showed that the value of ‘k’ ranged from 0.008-0.013 and 0.009-0.015 /min in un-blanched and blanched samples respectively. The drying temperature caused decrease in color parameters, chlorophyll content, however RR was observed to increase with the drying temperature. The moisture, chlorophyll content, color values (L* a* b*) and rehydration ratio was observed to decrease with the storage. The better desirable quality attributes of green beans were retained in HDPE as compared to LDPE. In conclusion it was suggested that drying temperature effects the quality attributes of the green beans and also the packaging material also influence the storage stability of the dried green beans.

PRODUCTION AND STORAGE STABILITY OF ANTIOXIDANT FIBER FROM PIGEON PEA (CAJANUS CAJAN) POD

Pigeon pea (Cajanus cajan) pods were considered byproducts obtained from food industry which was raw material for the production of antioxidant fiber powder in this investigation. The effects of pretreatment (washing and blanching) and drying temperatures (60, 70, and 80C) on total crude fiber contents, total phenolic concentration and antioxidant activity by the method of DPPH radical scavenging activity and FRAP were evaluated. The results showed that blanched (60C) samples had the shortest drying times of 9.03 h. However, blanching significantly (p≤0.05) reduced antioxidant capacity of dried pigeon pea pod powders when compared to washing with tap water and fresh sample. Higher drying temperature tended to decrease fiber contents and antioxidant activity of dried powder. The pigeon pea pod powders were stored in ziplock bags or vacuum packaging at room temperature for 8 weeks. The moisture content of the powder kept in both packaging increased over time, which correlated with the water activity during 8 weeks of storage. In addition, storage times caused a decline in the levels of total phenolic concentration, DPPH, and FRAP values. The amount of total phenolic concentration, DPPH and FRAP of vacuum-packed samples were significantly higher than those stored in ziplock bags during storage. It could be concluded that washing with tap water and drying temperature of 60C was the most suitable condition for the process of fiber powder with antioxidant activity preparation from pigeon pea pod. Moreover, vacuum packaging method was sufficient to maintain the antioxidant capacity of the sample for 8 weeks.

Influence of varying preservation methods on the shelf life and proximate composition of Pleurotus plumonarius (Fr) Quel cultivated on Andropogon gayanus substrate

The objective of the work was to evaluate the influence of preservation methods on the storability and proximate composition of Pleurotus pulmonarius. The experiment was laid out in a completely randomized design (CRD) with three replicates. Freshly harvested mushrooms grown on Andropogon gayanus substrate and analyzed for its proximate composition were divided into four portions: sun dried (SD), oven dried (OV), blanched and stored directly in citric acid solution at varying concentrations (conc.). The microbial load count of the preserved samples and sensory evaluation carried out were significant (P&amp;lt;0.05) with sun and oven dried samples most preserved followed by blanched samples stored in citric acid solutions, with 0.5% conc. taking the lead. The proximate results showed that the protein, fat, and ash contents of mushroom preserved in citric acid solution decreased while sun and oven dried samples increased significantly with increase in fibre and carbohydrate. The result of the sensory evaluation on colour, texture and flavour showed that blanched sample stored in 0.5% citric acid solution was most preferred for colour, odour and texture.

Effect of Moist Cooking Blanching on Colour, Phenolic Metabolites and Glucosinolate Content in Chinese Cabbage (Brassica rapa L. subsp. chinensis).

Non-heading Chinese cabbage (Brassica rapa L. subsp. chinensis) is a widely consumed leafy vegetable by the rural people in South Africa. Traditional blanching methods (5%, 10% or 20% lemon juice solutions in steam, microwave treatments and hot water bath at 95 °C) on the changes of colour properties, phenolic metabolites, glucosinolates and antioxidant properties were investigated in this study. Blanching at 95 °C in 5% lemon juice solution maintained the chlorophyll content, reduced the difference in colour change ∆E, and increased the total phenolic content and the antioxidant activities (ferric reducing-antioxidant power assay (FRAP) and Trolox equivalent antioxidant capacity (TEAC) assay). The highest concentration of kaempferol-dihexoside, kaempferol-sophoroside, kaempferol hexoside, and ferulic acid was noted in samples blanched in 5% lemon juice, at 95 °C. However, concentrations of kaempferol O-sophoroside-O-hexoside was highest in raw leaf samples. Supervised Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) and the UPLC-MS and chemometric approach showed the acid protocatechuoyl hexose unique marker identified responsible for the separation of the blanching treatments (5% lemon juice at 95° C) and raw leaves. However, other unidentified markers are also responsible for the separation of the two groups (the raw leaves and the hot water moist blanched samples) and these need to be identified. Blanching at 95 °C in 10% lemon solution significantly increased the glucosinolate sinigrin content. Overall blanching at 95 °C in 5% lemon juice solution can be recommended to preserve the functional compounds in Nightshade leaves.

Improved Physicochemical and Structural Properties of Blueberries by High Hydrostatic Pressure Processing.

The use of high pressure on fruits and vegetables is today widely studied as an alternative to the traditional thermal preservation techniques, with the aim of better preserving nutritional and organoleptic properties. The use of high hydrostatic pressures (400–600 MPa; 1–5 min; room temperature) was tested on the physicochemical and structural properties of blueberries, in comparison to raw and blanched samples. High hydrostatic pressures led to higher tissue damages than blanching, related to the intensity of the treatment. The cellular damages resulted in leakage of intracellular components, such as bioactive molecules and enzymes. As a consequence, among the high pressure treatments, the resulting antioxidant activity was higher for samples treated for longer times (5 min). Pectinmethyl esterase (PME), deactivated by blanching, but strongly barotolerant, was more active in blueberries treated with the more intense high pressure conditions. Blueberry texture was better retained after high pressure than blanching, probably because of the PME effect. Blueberry color shifted towards purple tones after all of the treatments, which was more affected by blanching. Principal component analysis revealed the mild impact of high pressure treatments on the organoleptic properties of blueberries.