Amazonian palm tree fruits: From nutritional value to diversity of new food products

The rapid growth of the world population has increased the demand for new food sources, constituting a major challenge concerning the maximum use of existing food resources. The fruits of Amazonian palm trees have excellent nutritional composition and bioactive compounds. This review highlights four fruits of Amazonian palm trees that are still little explored by the food industry: açai (Euterpe oleracea), pupunha (Bactris gasipaes), buriti (Mauritia flexuosa), and tucumã (Astrocaryum aculeatum). This paper aims to inspire new ideas for researching and developing products for the food industry. It also explores the impacts of Amazonian palm fruits on health, highlighting their role in disease prevention through their nutritional effects.

Total and Free Hydrogen Cyanide Content and Profile of Bioactive Amines in Commercial Tucupi, a Traditionally Derived Cassava Product Widely Consumed in Northern Brazil

Tucupi is a broth derived from cassava roots which is produced after the spontaneous fermentation of manipueira (the liquid portion obtained by pressing cassava roots), followed by cooking. This product is widely consumed along with traditional dishes in the Brazilian Amazonia and is already used in different places worldwide. In this study, tucupi obtained from the markets of Belém (Pará, Brazil) and produced using agroindustrial (11 samples) and non-agroindustrial (11 samples) units were investigated to determine their physicochemical characteristics, total and free HCN contents, and free bioactive amine profiles. Most of the samples showed significant variations (p ≤ 0.05) in pH (2.82-4.67), total acidity (0.14-1.36 g lactic acid/100 mL), reducing sugars (up to 2.33 g/100 mL), and total sugars (up to 4.35 g/100 mL). Regarding the amines, four biogenic amines (0.5-4.2 mg/L tyramine, 1.0-23.1 mg/L putrescine, 0.5-66.8 mg/L histamine, and 0.6-2.9 mg/L tryptamine) and one polyamine (0.4-1.7 mg/L spermidine) were identified in the tucupi samples. Even in the tucupi produced using the agroindustrial units, which had quality seals provided by the local regulatory agency, high levels of biogenic amines (4.4-78.2 mg/L) were observed, as well as high dosages of total (8.87-114.66 mg/L) and free (0.80-38.38 mg/L) HCN. These facts highlight the need for better knowledge regarding the product manufacturing process to establish standardization and high-quality conditions for tucupi processing since high contents of biogenic amines and HCN are commonly associated with adverse health effects.

Nutritional and Technological Properties of Albino Peach Palm (Bactris gasipaes) from the Amazon: Influence of Cooking and Drying

This study aimed to subject the albino peach palm to cooking and drying processes and characterize the raw pulp (RP), cooked pulp (CP), raw pulp flour (RPF), and cooked pulp flour (CPF). The product's chemical composition, bioactive compounds, and physicochemical, color, thermal, morphological, and functional-technological properties were evaluated. The proximate composition showed that carbohydrates were the main constituents of all the products (69.59-72.08 g/100 g). The cooking process decreased the lipids (10.21 to 8.63 g/100 g), dietary fiber (13.64 to 12.81 g/100 g), and total sugar content (59.18 to 49.10 g/100 g) of the CP. The colorimetric parameters indicated a significant browning of the CP and CPF, which can be attributed to the Maillard reaction and lipid oxidation. After cooking, the total phenolic compound and ascorbic acid content decreased in the pulp. The RPF and CPF displayed different thermogravimetric behaviors. The spectral patterns in the infrared region showed the characteristic bands of organic compounds that are present in the structure of starches. The scanning electron microscopy showed amyloplast and fiber bundles with starches in the RP and gelatinized starch granules in the CP and CPF. The RPF presented small and heterogeneous starch granules with isolated amyloplast. The RPF and CPF showed different granulometric patterns and technological indices. The results suggest that the pulp and flour from the pulp of albino peach palms can be exploited by the food, pharmaceutical, and biotechnological industries.

Combined Pulsed Vacuum Osmotic Dehydration and Convective Air-Drying Process of Jambolan Fruits

Jambolan (Syzygium cumini) is a native fruit from Asia that has adapted well to the tropical climate of the Amazonian region. However, due to its limited annual availability and high perishability, the jambolan fruit is still underexploited. Thus, this study aimed to preserve the jambolan through a combined process of pulsed vacuum osmotic dehydration (PVOD) and convective air-drying and to monitor the total phenolic contents (TPCs) and total monomeric anthocyanins (TMAs) during these processes. To this end, jambolan fruits were pretreated with increasing PVOD times. After monitoring of moisture loss, solid gain, weight reduction, water activity, TPC, and TMA, pretreated (PT) and non-pretreated (NPT) fruits underwent convective air-drying (50-70 °C). The PVOD reduced half of the water present in the fruits; nonetheless, PVOD decreased the TPC and TMA over time. The increase in air-drying temperature shortened the drying time for both NPT and PT jambolan, and PVOD reduced even further the drying time of the fruits. Moreover, the fruits pretreated and dried at 60 °C showed promising results, potentially being a good alternative to extend the fruit's shelf life and make it available throughout the year.

Structural and Thermal Characteristics of Buriti Tree Gum (Mauritia flexuosa)

A polysaccharide was isolated from the exudate of a buriti tree trunk (Mauritia flexuosa). The molecular structure, thermal stability, morphology, crystallinity, and elemental composition of the product were investigated through spectroscopic techniques, such as Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR 1H and 13C), and energy-dispersive X-ray spectroscopy (EDS); thermogravimetric analysis (TG), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and X-ray diffraction (XRD). In addition to NMR molecular modeling studies, were performed to confirm the 1H and 13C chemical shifts to Gal and Xyl conformers. Buriti tree gum (BG) is an arabinogalactan, containing Rha, Ara, Xyl, and Gal, and degrades almost completely (98.5%) at 550 °C and has a maximum degradation peak at 291.97 °C, with a mass loss of 56.33%. In the temperature range of 255–290 °C, the energy involved in the BG degradation process was approximately 17 J/g. DSC indicated a glass transition temperature of 27.2 °C for BG, which had an irregular and heterogeneous morphology, with smooth or crumbling scaly regions, demonstrating the amorphous nature of BG that was confirmed by the XRD standard. EDS revealed the presence of carbon and oxygen, as well as calcium, magnesium, aluminum, silicon, chlorine, and potassium, in the BG composition.

Convective Drying of Purple Basil (Ocimum basilicum L.) Leaves and Stability of Chlorophyll and Phenolic Compounds during the Process

This study evaluated the effect of convective drying on the degradation of color and phenolic compounds of purple basil (Ocimum basilicum L.) leaves, and the hygroscopic behavior of dried leaves. The fresh leaves underwent drying at 40 °C, 50 °C, 60 °C, and 70 °C. Degradation of chlorophyll, flavonoids, and phenolic compounds were evaluated during drying and the hygroscopicity was evaluated through the moisture sorption isotherms. The drying mathematical modeling and the moisture sorption data were performed. The effective diffusivity for the drying increased from 4.93 × 10−10 m2/s at 40 °C to 18.96 × 10−10 m2/s at 70 °C, and the activation energy value (39.30 kJ/mol) showed that the leaves present temperature sensibility. The leaves dried at 40 °C had less degradation of phenolic compounds and color variation, but the drying process was too slow for practical purposes. Modified Page, Diffusion Approximation, and Verna models had excellent accuracy in drying kinetics. The isotherms showed that, in environments with relative humidity above 50%, the purple basil leaves are more susceptible to water gain, and at 8.83 g H2O/100 g db moisture, it guarantees the microbiological stability of the dried leaves. The Oswin model was the most suitable for estimating the moisture sorption isotherms of the dried leaves.

Moisture desorption behavior and thermodynamic properties of pulp and seed of jambolan (Syzygium cumini)

The study objectives were to establish isotherms and thermodynamic properties for the moisture desorption process of jambolan pulp (JP) and jambolan seed (JS), harvested in the city of Belém (Brazil). These characteristics can contribute for the proper selection of the operating drying conditions. Thus, the following essays were made for both JP and JS. Firstly, proximate composition was performed, followed by moisture desorption essays at 25, 35, 45 and 55 °C. In addition, six mathematical models were fitted to the experimental data to simulate the desorption behavior; and based on the chosen models, the thermodynamic properties were calculated. The results have shown that JP isotherms followed the typical behavior of products rich soluble solids, and JS isotherms were more influenced by protein components. The influence of temperature was evidenced throughout the entire range of water activity (aw) studied. The GAB and Oswin models represented the best fitted equations for the JP and JS, respectively. In general, the energies involved in the desorption process of jambolan showed a greater dependence of JP with the equilibrium moisture content (EMC), in comparison with JS. Still, there was an increasing tendency of the thermodynamic properties with EMC decreasing. Besides of being non-spontaneous processes, desorption phenomena of JP and JS were enthalpy-driven mechanisms.

Lactic Acid Bacteria and Bioactive Amines Identified during Manipueira Fermentation for Tucupi Production

There is scarce information regarding lactic acid bacteria (LAB) and the production of biogenic amines during manipueira fermentation for tucupi. Thus, the objective of this study was to isolate and identify LAB, and to determine their impact on bioactive amine formation. Spontaneous fermentation of manipueira was carried out at laboratory scale and selected LAB colonies were isolated and identified by sequencing techniques and comparison with sequences from a virtual database. Only two LAB species of the genus Lactobacillus were identified during fermentation: Lactobacillus fermentum and Lactobacillus plantarum. L. fermentum was the predominant, whereas L. plantarum was only detected in manipueira prior to fermentation. Spermidine and putrescine were detected throughout fermentation, whereas histamine was produced at the final stage. There was positive correlation between LAB counts and putrescine and histamine levels, suggesting that the identified LAB are responsible for the synthesis of these amines during manipueira fermentation. Genetic assays are needed to verify whether the LAB identified have the genes responsible for decarboxylation of amino acids.

Encapsulation of bioactive compounds extracted from plants of genus Hibiscus: A review of selected techniques and applications

The genus Hibiscus includes more than 250 species, and many studies showed that these plants contain bioactive compounds with technological potential to be used in the development of functional foods. However, the instability of these compounds during typical food processing conditions, such as exposure to high temperatures, pH changes and presence of light and oxygen have stimulated the use of encapsulation techniques to increase their stability and applicability. Among the existing Hibiscus species, only H. sabdariffa, H. cannabinus, and H. acetosella have been investigated in encapsulation studies, being spray drying the most common method approached. Considering the high technological potential offered by the incorporation of encapsulated bioactive compounds from plants of the genus Hibiscus in food formulations, this review discusses key information of selected encapsulation techniques, which represents promising alternatives to increase food systems' stability and stimulate the design of new functional foods. Relevant gaps in the literature were also noticed, mainly the lack of systematic studies regarding the composition of bioactive compounds after encapsulation, instead of total determinations, and biological activities in different analytical systems, such as antioxidant, antimicrobial and anti-inflammatory properties as well as bioaccessibility and bioavailability.

Peach palm flour: production, hygroscopic behaviour and application in cookies

In this work, two types of flour from peach palm fruits (Bactris gasipaes) were prepared to be used to produce cookies: one with the whole fruit (pulp + peel) and another one with only the pulp. Analyses of proximate composition, physicochemical and hygroscopic behaviour were carried out in both flour, as well as sensory analysis of the produced cookies. Both the types of flour did not differ statistically in total lipids, total carbohydrates and ashes (p > 0.05). Among the mathematical models tested for the prediction of the hygroscopic behaviour of both flour, Halsey model showed the best fit to the experimental data (R2 = 0.99 and P<10%). The cookies produced with both types of peach palm flour presented low moisture (4.9-6.2%), high lipid content (25.56-26.37%) and total carbohydrates (59.10-61.84%), resulting in a product with high total energetic value (501.8-502.8 kcal/100 g). Based on the results of acceptance test, both cookie formulations presented good sensory acceptance (>70%). The purchase intention inquiry showed that the cookie prepared with the whole fruit flour presented the highest percentage of purchase intention (85%), which demonstrate that the use of peach palm peels in the development of new food products represent an excellent alternative for the use of by-products.

Optimization of the spray drying process for developing cupuassu powder

A central composite design was used to optimize the spray drying process for developing cupuassu (Theobroma grandiflorum) powder. The influence of inlet air temperature (T_inlet) (120-180 °C), feeding rate (F_feed) (3-12 mL/min) and maltodextrin concentration (C_malto) (10-40%) on the properties of moisture, water activity (a_w), hygroscopicity, water solubility index (WSI), ascorbic acid (AA) and total phenolic compounds (TPC) were analyzed using response surface methodology and desirability function. In addition, powder morphology was assessed using scanning electron microscopy. The T_inlet and F_feed parameters significantly influenced the moisture and a_w, while the other responses (hygroscopicity, WSI, AA and TPC) were influenced by the T_inlet and C_malto parameters. The highest C_malto and intermediate T_inlet and F_feed levels showed the best morphological characteristics (particles integrity, spheres shapes and smooth surfaces). The desirability function defined the optimal process conditions as T_inlet = 150 °C, F_feed = 7.5 mL/min and C_malto = 40%.

Enzyme-assisted extraction of phenolic compounds from murucizeiro leaves (Byrsonima crassifolia)

The aim of this work was to evaluate the enzyme-assisted extraction of phenolic compounds from murucizeiro leaves (Byrsonima crassifolia) employing response surface methodology (RSM), in order to determine the best extraction conditions. The chemical composition of the leaves and characteristics of the enzymes were determined. The independent variables were temperature (19 to 70°C), pH (2.4 to 7.5) and reaction time (19 to 220 minutes). A conventional and optimized triple extraction with organic solvents was used as control. As result to solvent extraction was observed 73.28 mg of gallic acid equivalents (GAE) g-1 DM, while under the best condition for enzyme-assisted extraction (temperature: 60°C; pH: 4.5; and time: 220 min), the concentration was 90.65 mg GAE g-1. The independent variables significant were: temperature, pH and log time at the linear level and temperature at the quadratic level. A similar methodology could be encouraged for other natural products rich in phenolic compounds.

Optimization of spray drying process parameters for tucupi powder using the response surface methodology

A completely randomized 2³ factorial experimental design was used to optimize the process parameters for obtaining tucupi powder through spray drying. The effects of the process variables [inlet air temperature (IT), feed flow rate (FR), and maltodextrin concentration (MD)] on the product properties [moisture, water activity (a_w), hygroscopicity, water absorption index (WAI), water solubility index (WSI), total color difference (ΔE*), and β-carotene content] were studied using the response surface methodology (RSM) and linear perturbation plot. In addition, scanning electron microscopy (SEM) images were obtained of the product. According to ANOVA and the regression coefficients (R² > 0.90), the RSM models were significant and IT was the variable with the greatest impact on most of the responses. SEM shows that the powders obtained with higher IT and MD and lower FR were more uniform, with smooth and intact surfaces. The optimal conditions estimated for the process were IT at 214 °C, FR at 8.67 mL/min, and MD at 27%. Under those conditions, the product's minimum values of moisture (9.56 g/100 g), a_w (0.101), hygroscopicity (37.45% d.b.), and ΔE* (17.05) and maximum values of WAI (6.68 g/g d.b.), WSI (84.77%), and β-carotene (13.72 µg/g) were estimated.

Combined osmotic dehydration and drying process of pirarucu (Arapaima gigas) fillets

The osmotic dehydration (OD) and complementary drying of pirarucu (Arapaima gigas) fillets were studied. Pieces of the dorsal portion of pirarucu (60 mm × 20 mm × 10 mm) underwent OD in a binary solution (NaCl-water) with the application of vacuum pulse following a central rotatable composite design. The effect of the following process variables was assessed: temperature (20-40 °C), osmotic solution concentration (15-25% NaCl), and vacuum pulse pressure (7-101 kPa) on water loss (WL), solid gain (SG), and water activity (a_w). OD kinetics was obtained and the Peleg model was fitted to WL and SG data. The osmotically dehydrated pirarucu was dried (40-70 °C) in a fixed-bed dryer and mathematical models were fitted to the drying data. The optimal operational condition for the OD process was 35 °C, solution with 25% NaCl, and atmospheric pressure, which yielded WL of 14.87 ± 1.46%, SG of 8.56 ± 0.45%, and a_w of 0.87 ± 0.02. The Peleg model efficiently predicted the WL and SG kinetics. The increase in the water loss in drying was more evident at low temperatures (40-50 °C) with effective diffusivity ranging from 10.85 × 10^-9 to 12.30 × 10^-9 m²/s. The Midilli and Page models efficiently predicted the drying kinetics.

Anthocyanins of Jambolão (Syzygium cumini): Extraction and pH-Dependent Color Changes

Jambolão fruits are promising sources of anthocyanins, and in this study, the jambolão fruit from the Brazilian Amazonian region was characterized and the efficiency of six ethanol-based solutions to extract anthocyanins was determined. Moreover, the color changes of anthocyanin extracts, as influenced by different pH conditions (pH from 1.0 to 8.0), were evaluated. The fruits exhibited high contents of total anthocyanins (296 mg/100 g) and the CIELAB parameters characterized jambolão as a purple-red colored fruit (a* = 20.30, b* = -4.17, and hab∘= 348.39). Among the six different ethanol-based solutions, ethanol 95% with 1% of HCl (v/v) was the most efficient solution to extract anthocyanins from jambolão fruits. Furthermore, the CIELAB parameters were characterized as useful tool to monitor the color changes of anthocyanins of jambolão over the tested pH range. Therefore, jambolão fruits from Amazonian region have technological potential for the application by food, pharmaceutical, and cosmetic industries.

PRACTICAL APPLICATION

Jambolão fruits are great source of anthocyanins and the incorporation of these natural pigments as food colorants is not only valuable to improve overall appearance, but it is also beneficial to human health. The production of natural extracts with high levels of anthocyanins from jambolão can be considered a very useful approach to the food, pharmaceutical and cosmetic industries.

Influence of the process parameters on osmotic dehydration of mapara (Hypophthalmus edentatus) fillet

The effects of temperature, time, pressure and brine concentration were assessed during osmotic dehydration (OD) of H. edentatus fillet. The response surface methodology (RSM) showed that using vacuum during the OD process did not cause a statistically significant change (p > 0.05) on the water loss (WL), solid gain (SG) and water activity (aw). The other factors showed a statistically significant effect (p ≤ 0.05) on at least one of these responses. Through RSM, the following condition could be defined for the OD process: brine concentration at 25 % NaCl, 25 °C, 120 min and atmospheric pressure. The Azuara model was shown to be effective in predicting the WL and SG kinetics during the OD process. The simplified solution of Fick's second law of diffusion for a slab geometry was used to calculate the average values of apparent diffusion coefficient (Deff), namely 4.73 × 10(-10) m(2)/s for WL and 1.33 × 10(-9) m(2)/s for SG.

Rheological behavior of Brazilian Cherry (Eugenia uniflora L.) pulp at pasteurization temperatures

The rheological behavior of Brazilian Cherry (Eugenia uniflora L.) pulp in the range of temperatures used for pasteurization (83 to 97 °C) was studied. The results indicated that Brazilian Cherry pulp presented pseudoplastic behavior, and the Herschel-Bulkley model was considered more adequate to represent the rheological behavior of this pulp in the range of temperatures studied. The fluid behavior index (n) varied in the range from 0.448 to 0.627. The effect of temperature on the apparent viscosity was described by an equation analogous to Arrhenius equation, and a decrease in apparent viscosity with an increase in temperature was observed.