Roberta Dordoni

Impact of Several Pre-treatments on the Extraction of Phenolic Compounds in Winegrape Varieties with Different Anthocyanin Profiles and Skin Mechanical Properties

This study was performed to evaluate and compare the effects of different pre-treatments of whole grape berries (freezing with dry ice or in a cold room, steam blanching with different exposure times, and microwave heating with different exposure times and microwave power density) on total content of some phenolic compounds and the composition of individual anthocyanins released into the pulp during the treatment and those extracted during the maceration step. Two red winegrape varieties with different proportions of di- and trisubstituted anthocyanins were used (Nebbiolo and Barbera, respectively). Pulp-extracted anthocyanins were more significantly influenced by the pre-treatment. The results highlighted that freezing with dry ice, followed by freezing in a cold room and steam blanching for 5 min, have a great potential from an industrial point of view. They facilitated the extraction of anthocyanins in the must prior to maceration, when compared with the control samples, increasing their total content (+37.8-83.6%), and modifying the anthocyanin profile through the enrichment in the most stable compounds (+2.8-6.6% malvidin derivatives) to the detriment of others more prone to oxidation (-0.8-11.0% cyanidin derivatives). In Nebbiolo winegrapes, an improved extraction of low- and high-molecular weight flavanols into the pulp was also observed (+60.4-73.4%). Significant relationships between the phenolic composition of treated berries and the corresponding skin mechanical properties were also studied, but they were variety dependent. Discriminant analysis permitted a correct classification of the samples according to the variety and pre-treatment.

Odor-active Compound Adsorption onto Bentonite in a Model White Wine Solution

This work extends the concepts proposed in a previous research paper about the interaction between the aroma of two white wines and bentonites. Such previous results led to hypothesized that some odor-active compounds were removed through direct adsorption mechanism on the clays. As a consequence, this paper examined the adsorption isotherms at 17±1°C of three bentonite samples added in three different amounts to a model white wine without the presence of wine macromolecule. The clays were analyzed for the elemental composition, the surface charge density, and the specific surface area (SSA) and differences were analyzed by Tukey’s test. The analysis of variance (ANOVA) was used to demonstrate the significance of the bentonite on the aroma reduction. The Langmuir and the Freundlich models were fitted to the adsorption data. The most experimental adsorption isotherms were robustly fitted by the Freundlich equation indicating that, under the condition of the study, the adsorption process more frequently occurred with a heterogeneous energy distribution of an infinite number of surface active sites. Overall, the modeling prediction ability tested by the error on r 2 in cross validation enhanced differences both among the odor-active compounds and among the clays. Samples having a lower SSA value and a greater charge density per surface unit seemed to interact with most of the odor-active compounds primarily through physical mechanisms. Differently, the clay with a large SSA value and a low charge density per surface unit promoted stronger adsorptions that were probably driven by chemical interactions especially for ethyl esters. For the tested odor-active compounds differences in the adsorption intensity and capacity depended mainly on the bentonite characteristics rather than on the properties of the substances.

Vinegar Production from Pineapple Wastes –preliminary Saccharification Trials

This study is located in the within of a research devoted at processing wastes both in developing and in developed Countries, so reducing both environmental pollution and seasonal fruit losses. In particular, the full work intended to completely process pineapple wastes into vinegar which may be then used as dressing, food preservative, and disinfectant. The preliminary trials presented here deepened the first process step (i.e. the saccharification) and looked into the feasibility of producing the greatest yield of reducing sugars from peels and core of pineapples. Wastes were cut into thin strips, chopped in a mixer, and divided into samples of peel and core to which distilled water was added. For enhancing reducing sugar yield, physical treatments were arranged to disaggregate the fibrous structure followed by enzyme treatments to breakdown cellulose polymers and to hydrolyse sucrose. The optimal time-temperature conditions of each process step were searched for gaining the highest reducing sugars yield at the end of the saccharification. Cellulolytic enzymes were tested for 4-8-18-24 h at 30-40-50 °C, invertase addition was arranged, and amylolytic enzymes were evaluated. All determinations were done in duplicate and a factorial ANOVA with Tukey’s test at p ≤ 0.05 was used to measure the significance of the differences among treatments. The conditions allowing the greatest reducing sugar yield were: the addition to 100 g of waste fresh weight (fw) of 0.025 mL of thermostable α-amylase before a 10 min treatment at 143.27 kPa followed by 24 h-50 °C incubation with 0.05 g pectinase/kgfw, 6 g cellulase/kgfw, 1 g hemicellulase/kgfw, and 0.05 % glucoamylase and pullulanase (Venzyme/kgfw). Then, samples were incubated with 0.05 g invertase/kgfw for 3 h at 50 °C. Under these conditions, more than 100 g of reducing sugars per kg of fresh peels and about 330 g of reducing sugars per kg of fresh core were obtained.

Metabolite profiling and volatiles of pineapple wine and vinegar obtained from pineapple waste

Vinegar is an inexpensive commodity, and economic considerations require that a relatively low-cost raw material be used for its production. An investigation into the use of a new, alternative substrate - pineapple waste - is described. This approach enables the utilization of the pineapples (Ananas comosus) peels and core, which are usually discarded during the processing or consumption of the fruit. Using physical and enzymatic treatments, the waste was saccharified, and the resulting substrate was fermented with Saccharomyces cerevisiae for 7-10days under aerobic conditions at 25°C. This resulted in an alcohol yield of approximately 7%. The alcoholic medium was then used as a seed broth for acetic fermentation using Acetobacter aceti as the inoculum for approximately 30days at 32°C to obtain 5% acetic acid. Samples were analyzed at the beginning and end of the acetification cycle to assess the volatile and fixed compounds by GC-MS and UHPLC-QTOF-MS. The metabolomic analysis indicated that l-lysine, mellein, and gallic acid were significantly more concentrated in the pineapple vinegar than in the original wine. Higher alcohols, aldehydes, and ketones characterized the aroma of the final pineapple vinegar, whilst off-flavors were significantly reduced relative to the initial wine. This study is the first to highlight the metabolite profile of fruit vinegar with a slight floral aroma profile derived from pineapple waste. The potential to efficiently reduce the post-harvest losses of pineapple fruits by re-using them for products with added food values is also demonstrated.

Waste grape skins : evaluation of safety aspects for the production of functional powders and extracts for the food sector

ABSTRACT Skin powders and aqueous alcohol extracts were obtained from waste marcs from different grape varieties (Barbera, Nebbiolo, Pinot Noir, Chardonnay, Moscato and Müller-Thurgau). Both skins and extracts were analysed for the content of chemical contaminants: ochratoxin A (OTA), biogenic amines (BIAs), pesticides and metals. OTA was detected in low concentrations in Barbera, Moscato and Nebbiolo skins, but only in Barbera and Moscato extracts. Cadaverine, putrescine, ethanolamine and ethylamine were found in extracts at very low levels, while potential allergenic amines, tyramine and histamine, were never detected. Different pesticides were present in both skins and extracts. Pb and Cd were found in trace only in the powders, and K, Ca and Mg were the most abundant elements in both skin powders and extracts. Concentrations of the different contaminants were related to fibre content or total phenolics content of powders and extracts, respectively, in order to evaluate their use in the food sector. Graphical Abstract

Effect of Bentonite Characteristics on Wine Proteins, Polyphenols, and Metals under Conditions of Different pH

Studies have yet to evaluate how bentonite properties may affect the protein profile, polyphenol content, metal concentration, and heat stability of a white wine at different pH values. Therefore, this work assessed the proteins, polyphenols, metals, and haze forming tendency when heating white wine samples before and after a fining treatment with four activated sodium bentonites in a typical wine pH range (3.00 to 3.60). Soluble wine proteins were separated by sodium dodecyl sulfate - polyacrylamide gel electrophoresis, and gel images were compared using the Quantity One software package (Bio-Rad Laboratories, Inc., Hercules, CA). The wine haze forming tendency, metals, and polyphenols were measured using heat tests and International Organisation of Vine and Wine (OIV) methods. Low molecular mass proteins were efficiently removed by all of the bentonites, regardless of the pH. High and medium molecular mass proteins were less likely to be removed and the efficiency, which depended on the pH, was variable. Reductions of vacuolar invertase (GIN1) and VVTL1 fractions of the thaumatin-like proteins were induced by bentonites with pH values less than 10. These bentonites were affected to a lesser extent by the negative effect of acidic pH. The reduction in haze forming tendency of the unfined Erbaluce wine was particularly noticeable in bentonite fined samples heated at 50 to 60°C, 60 to 80°C, and 70 to 80°C at pH 3.17, pH 3.30, and pH 3.60, respectively. The poor removal of glycoproteins (YGP1 and Hmp1) at higher pH values contributed to an increased thermal stability. The exchange of cationic species, notably sodium and potassium, between the bentonites and the wine was related more to the wine pH than to the clay type. Finally, the extent of polyphenol removal correlated with the amount of protein removed. When protein removal did not occur, the reduction of polyphenols was driven by the specific surface area and the surface charge density of the bentonite.

Innovations in the Use of Bentonite in Oenology: Interactions with Grape and Wine Proteins, Colloids, Polyphenols and Aroma Compounds

Bentonite is used in oenology to improve the limpidity and the stability of wine and to predict the formation of deposits in the bottle. The exchangeable cations in its lamellar structures strongly influence some properties, such as the specific surface, the exchange capacity and the adsorption behavior. The unintended use of bentonite for juice settling and/or for wine fining produces jeopardized effects on colloidal and protein stability, the aroma compounds and sensory profiles. The interactions with haze-forming proteins, other colloids, as well as aroma compounds and phenols would have been to discover as the modulation of wine colloids by an adjuvant severely affects the wine resilience and the sensory profile. This chapter reviews several studies that focus on the impact of commercial bentonite samples used for both juice clarification and wine fining on the colloids, proteins, phenols and aroma compounds of white and red wines. Some parameters of practical value, such as the wine heat stability, the concentrations of total and haze-forming proteins and the content of the most relevant aromas, have been assessed to track the effects of bentonite and to achieve findings that are applicable to the field of oenology.

Process development for maltodextrins and glucose syrup from cassava

The objective of this study was to produce maltodextrins (MD) and glucose syrup (GS) throughout a smallscale process from the direct conversion of cassava roots collected in Burundi and previously detoxified. The detoxified cassava slices were blended with water at ratios of 1:1.0; 1:1.3; 1:1.6. Then, the cassava mash was undergone previously to gelatinization and then to liquefaction experiments aimed at obtaining MD with a Dextrose Equivalent (DE) value < 20. The doses of 0.013, 0.016, 0.019, 0.025, and 0.075 % (venzyme/wfresh mash) thermostable α-amylase (Liquezyme-X) were investigated to be added to cassava mash at pH 6.5 before and after 10 min - 90 °C step at atmospheric pressure (patm) or 143.27 kPa (110 °C) allowing the starch gelatinization. Then liquefaction times of 10, 15, 20, 30, 40, 45, 60, 90 and 120 min were tested. The saccharification step followed the liquefaction in order to obtain a GS with DE close to 99. The hydrolyzed cassava mash from liquefaction experiments was added at pH 5.4 and 60°C with 0.019 % (venzyme/wfresh mash) glucoamylase (Dextrozyme GA) and pullulanase (Dextrozyme GX) testing 1, 2, 4, 6, 18, 24, and 48 h incubation times. All experiments were done in duplicate and analysis of variance (ANOVA) with Tukey’s test at p≤0.05 was used to measure the effect of changing variables among treatments. Correlation Pearson’s test were applied to measure the strength of the interactions between the variables. Results showed that the 10 min-143.27 kPa (on lab-scale) and the 12 min-145÷152 kPa (on small-scale) burst of starch granules in 1:1.6 cassava: water mash with 0.013 % (venzyme/wfresh mash) thermostable αamylase at pH 6.5 followed by 15 min-90 °C liquefaction phase at patm allowed at obtaining MD with DE value < 20. In order to gain a GS having a DE value close to 99, a 4 h-60 °C saccharification phase at pH 5.4 with 0.019 % (venzyme/wfresh mash) glucoamylase and pullulanase should be carried out. Finally, highly significant correlations were found out between the water amount in the cassava mash, the concentration of the α-amylase enzyme, and the liquefaction time. This type of process had the advantage to be simple and practical, with reduced working times and enzyme doses, so to be popularizing especially in developing Countries. Further investigations are needed on some energy intensive operations, as like as pH adjustment, pressure increasing, and heating.

Mild Process for Dehydrated Food-grade Crude Papain Powder from Papaya Fresh Pulp: Lab-scale and Pilot Plant Experiments

Proteases are protein digesting biocatalysts long time used in the food industry. Although many authors reported the crystallization of papain and chymopapain from papaya latex, the powder of crude papain had the largest application as food supplements due to its highly positive effect on the degradation of casein and whey proteins from cows milk in the stomach of infants. As the industrial preparative procedures have not been extensively applied, this study aims at producing dehydrated crude papain from fresh papaya pulp, planning lab-scale trials, followed by process development toward the pilot industrial-scale. In the lab-scale experiments, the enzyme activity (EA), expressed as protease unit (PU) /g, were evaluated on pulp and papain standard before and after a 2 h thermal treatment at 70 °C, 90 °C, and 120 °C, and the thermal behavior was monitored by means of differential scanning calorimeter (DSC). The process development toward the pilot-scaling optimized: the homogenization of the fresh pulp, followed by its filtration at high pressure (HP) in order to obtain the vegetation water and the pre-dehydrated pulp which was then oven dried varying the time-temperature conditions (4 h-80 °C; 2 h-120 °C; 30 min-150 °C). Proceeding at higher temperatures for a shorter time allowed obtaining commodity-related and technologically valid products. In the final pilot-scale step, filtration was done with vertical HP filter press, and final dehydration was performed with 2-step turbo-drying: the first aimed to concentrate with 2 min air flow (500 m 3 /h) at 200 °C, the second aimed to dry with 10 min air flow (500 m 3 /h) at 120 °C. The resulting dehydrated pulp was grinded with ball-mill to obtain a stable powder. Starting from 90±2 % pulp moisture, the two turbo-drying steps lowered the water content from 75±4 % to 50±2 % and from 50±2 % to 8±1 %, respectively. The enzyme release from the final powder highlighted an EA of the food-grade crude papain powder extract of 28 PU/g. The thermal steps provided with turbo-driers permitted to maintain a fraction of sugars and pectin acting as a protective structure, so increasing the digestion effects provided by papain. Vegetation waters were ultra-filtered allowing at obtaining a concentrated pectin suspension and rich in nutrient waters which can be reused along the food chain. Further efforts should be made to implement this procedure as potential alternative for the dehydrated crude papain production, deepening the impact of process variables on this matter.

Design and development of an eco-innovative sorghum snack

A new and sustainable cereal bar (named SOcrock) was created in the context of EcoTrophelia, an European competition originated from the EcoTroFood project (from the European Commission’s Competitiveness and Innovation Framework Programme) and dedicated to student teams for creating prototype of food products with quality and environmentally friendly aspects. The designed product recipe consisted only of white sorghum, powdered grape seeds, honey, and dark chocolate. This essential composition was formulated in order to boost nutritional added value such as presence of polyphenols, high fiber content, low level of sodium, and a low caloric intake, all within an organic product, free of gluten and preservatives. A selected variety of white sorghum was the basic ingredient of the product: versatile, with nutritional properties similar to corn, sorghum has lower water requirements and withstands high temperatures brilliantly. In this product sorghum was transformed and used in three forms: as blown grain, as syrup (obtained by enzymatic hydrolysis of the grains) and as fiber (by-product of syrup production). Further innovation was the direct inclusion of grape seeds (by-products from distillery) that represents a simple solution for the recovery of low cost bio-active compounds. The preparation of the finished product was obtained by a semi-industrial processing line consisting in a cooker equipment (with hollow space in a diathermic oil bath) complete of planetary system and overturning head, cooling tunnel, and heat sealing packaging machine. The product impact on the ecosystem in terms of greenhouse gas emissions, water use, and exploitation of natural resources was evaluated. It resulted in a Type II environmental label which highlighted the product always falls in the best categories for sustainability. The developed product was awarded the bronze prize at the 2013 EcoTrophelia European final.