Optimization, Modeling, and Online Monitoring of the Enzymatic Extraction of Banana Juice

This article focuses on the optimization, modeling, and online monitoring of banana juice production through an enzymatic method. In order to perform this task, a batch reactor was designed with automatic control over the temperature and the agitation speed as well as online monitoring of torque. The experiments were carried out with the Musa AAA Cavendish banana variety (Enano gigante), the main variety planted in Mexico. Three different ripening stages were evaluated. Optimization of juice extraction was evaluated as a function of the pulp/water relationship and the concentration of the enzyme complex. The results showed that the adding of water had no influence on the extraction of banana juice, and the optimal enzyme concentration per kilogram of banana pulp was found. Based on a fuzzy logic approach, it was possible to relate the initial torque with the ripeness stage. Furthermore, an observable dynamical model based on ordinary differential equations and fuzzy logic is presented. With this model, the relationship between the torque dynamic and the instant juice yield was found to depend on the amount of enzyme, the temperature, and the maturity stage of the banana used. In addition, a principal components analysis was used to classify and to relate the final juice characteristics (e.g., L, a, and b colorimetric components) to the processing conditions and the final appreciation of a group of sensorial panelists. Additionally, a robust observer was designed and implemented to filter the noise present in the torque signal and to predict the instant juice yield.     

Applicability of NIR spectroscopy to determine oil and other physicochemical parameters in Rosa mosqueta and Chilean hazelnut

Due to the increasing interest in certain components, specially the oil, from non-conventional seeds as Rosa mosqueta (Rosa rubiginosa) and Chilean hazelnut (Gevuina avellana), quick determinations of oil and other parameters were carried out by using near-infrared (NIR) spectroscopy. Moisture, oil, fiber (as acid detergent fiber) and protein from solid samples of the seeds as mentioned, along with those of soybean (Glycine max), already analyzed by NIR and for serving as control for the variability of the method, were studied. Sample interactions to NIR radiations were processed using the multivariate regression algorithm Partial Least Squared (PLS) to build a calibration model. Standard error of cross-validation (SECV) was used to estimate the prediction error. Moisture of Rosa mosqueta, Chilean hazelnut presscake and soybean meal (in the ranges 10–15, 10–15, 8–10%, respectively), acid detergent fiber (60–68, 12–16, 10–15%, respectively), oil (1–4, 14–20, 5–13%, respectively) and protein (1–5, 8–15, 27–45%, respectively) were previously determined by wet analysis using standard methods, so creating a library. The possibility to analyze parameters from very different oilseeds with an acceptable uncertainty was also established. Standard errors of cross-validation were between 1.25 and 2.99%, being the oil content the best predicted parameter.     

Relationships between cheese-processing conditions and curd and cheese properties to improve the yield of Idiazabal cheese made in small artisan dairies: A multivariate approach

Very diverse cutting and cooking intensity processes are currently used in small artisan dairies to manufacture Idiazabal cheese. The combination of the technical settings used during cheese manufacturing is known to affect cheese composition and yield, as well as whey losses. However, the information regarding the effect on microstructure and texture of cheese is scarce, especially in commercial productions. Therefore, the effect of moderate- and high-intensity cutting and cooking processes on whey losses, curd-grain characteristics, microstructure and cheese properties, and yield were analyzed. Three trials were monitored in each of 2 different small dairies during the cheesemaking of Idiazabal cheese, which is a semihard cheese made from raw sheep milk. The role and know-how of the cheesemakers are crucial in these productions because they determine the cutting point and handle semi-automatic vats. The 2 dairies studied used the following settings: dairy A used moderate-intensity cutting and cooking conditions, and dairy B used high-intensity cutting and cooking settings. Multiple relationships between cheese-processing conditions and curd, whey, and cheese properties as well as yield were obtained from a partial least square regression analysis. An increased amount of fat and casein losses were generated due to a combination of an excessively firm gel at cutting point together with high-intensity cutting and cooking processes. The microstructural analysis revealed that the porosity of the protein matrix of curd grains after cooking and cheese after pressing was the main feature affected, developing a less porous structure with a more intense process. Moderate-intensity cutting and cooking processes were associated with a higher cheese yield, regardless of the longer pressing process applied. No significant differences were observed in cheese composition. After 1 mo of ripening, however, the cheese was more brittle and adhesive when the high-intensity cutting and cooking process was applied. This could be associated with the composition, characteristics, and size distribution of curd grains due to differences in the compaction degree during pressing. These results could help to modify specific conditions used in cheesemaking, especially improving the process in those small dairies where the role of the cheesemaker is crucial.     

Climate dependence of energy saving strategies in public buildings characterized by change of use: an original case study

In the perspective of reducing land occupation of built environments, the most efficient strategy is to increase the reuse of obsolete or abandoned constructions instead of designing new buildings. This is particularly true regarding public buildings, usually characterized by considerable dimensions. The paper is focused on this issue, particularly on its energy implications. It analyzes the headquarters of the “G. D’Annunzio” University in Pescara, Italy, initially designed for commercial use and later converted to a university building during its construction. The authors first carried out a numerical analysis of the building energy performance in its current state and then they proposed some improvement interventions evaluating their incidence on the annual energy balance of the building, showing how the most commonly used energy saving strategies do not give the best results in any case, being greatly influenced by the climatic zone in which the building is located. Starting from these considerations, the authors carried out the analysis by considering three different Italian climatic conditions so as to determine their influence on the building energy performance and to define the best strategy for energy requalification in each climatic zone.     

A new exact numerical series for the determination of the Biot number: Application for the inverse estimation of the surface heat transfer coefficient in food processing

As a corollary to a previous work, a new exact numerical series is deduced for the Biot number for the case of elementary geometries. This series is rapidly converging, allowing a very accurate approximation when truncated at its first term.On the basis of this first approximation to the series, the equation is generalized and proposed to indirectly estimate the Biot number for regular geometries.     

A Cassava Starch–Chitosan Edible Coating Enriched with <Emphasis Type="Italic">Lippia sidoides</Emphasis> Cham. Essential Oil and Pomegranate Peel Extract for Preservation of Italian Tomatoes (<Emphasis Type="Italic">Lycopersicon esculentum</Emphasis> Mill.) Stored at Room Temperature

The effect of edible cassava starch–chitosan coatings incorporated with rosemary pepper (Lippia sidoides Cham.) essential oil and pomegranate peel extract on the shelf-life of tomatoes during storage at 25 °C for 12 days was investigated. Sixteen formulations, containing 10 g L^?1 cassava starch and various concentrations of chitosan (5, 10, 20, 30 g L^?1), essential oil (0, 2.5, 5, 10 mL L^?1) and pomegranate peel extract (0, 5, 10, 20 mL L^?1) were prepared and applied to tomatoes. Physical–chemical and microbiological analyses were performed on days 1, 4, 8 and 12. Most of the coatings delayed the ripening of tomatoes, lowering the total soluble solids (38?44 g sucrose kg^?1) and weight loss (93?128 g kg^?1) and maintaining constant firmness compared to the uncoated tomatoes (45 g sucrose kg^?1, 175 g kg^?1) at 12 days of storage. Conversely, except red intensity (a*), which was higher for the uncoated samples, the colour parameters (L*, b*) of the coated and control tomatoes were similar at the end of storage. Uncoated and coated tomatoes showed no contamination during storage. The coatings showed potential to maintain the quality of tomatoes during storage at 25 °C for 12 days. In this context, tomatoes coated with the formulation comprising 10 g L^?1 cassava starch, 10 g L^?1 chitosan, 10 mL L^?1 essential oil and 20 mL L^?1 pomegranate peel extract showed the lowest weight loss and reduced total soluble solids content compared with uncoated ones.     

Postharvest performance of fresh‐cut ‘Big Top’ nectarine as affected by dipping in chemical preservatives and packaging in modified atmosphere

Fresh‐cut ‘Big Top’ nectarines were dipped in 2% (w/v) ascorbic acid–1% (w/v) calcium lactate and stored at 4 °C for up to 12 days in 10 kPa O₂‐ and 10 kPa CO₂‐modified atmosphere packaging (MAP). The used microperforated plastic film allowed O₂ and CO₂ concentrations to reach steady values from the fifth day in storage onwards. Samples stored in MAP after chemical dipping showed the highest visual quality score, slight browning symptoms, increment in firmness and very low ethanol and acetaldehyde content. The chemical dipping also increased antioxidant capacity, probably due to the effect of ascorbic acid. The results suggested that the control of yeasts was mainly exerted by MAP, whereas only a slight effect was achieved by the chemical dipping. Therefore, MAP plus ascorbic acid/calcium lactate dipping was the best combination to preserve phytochemical content, antioxidant capacity and microbiological safety of fresh‐cut nectarines during storage.     

The applied pretreatment (blanching,ascorbic acid) at the manufacture process affects the quality of nectarine purée processed by hydrostatic high pressure

A nectarine purée was manufactured with different pretreatments (thermal blanching or ascorbic acid – AA – addition), and then, the purée was processed by high‐pressure treatment to evaluate the effect of the initial manufacture conditions in the stability of the processed purées. A thermal treatment was also carried out to compare the effect with the high‐pressure processing (HPP). All applied processes were effective to ensure the microbiological safety of the purées. However, the pretreatment (thermal blanching or AA addition) applied during the manufacture affected the final quality of the processed purées. Initially, the AA addition had a protective effect on colour degradation during the manufacture of the purées; however, when these purées were treated by HPP showed less colour stability during storage, lower bioactive compounds content, and antioxidant activity. In contrast, purées with an initial thermal blanching maintained better the quality after HPP and during storage.     

Automated Systems Based on Machine Vision for Inspecting Citrus Fruits from the Field to Postharvest—a Review

Computer vision systems are becoming a scientific but also a commercial tool for food quality assessment. In the field, these systems can be used to predict yield, as well as for robotic harvesting or the early detection of potentially dangerous diseases. In postharvest handling, it is mostly used for the automated inspection of the external quality of the fruits and for sorting them into commercial categories at very high speed. More recently, the use of hyperspectral imaging is allowing the detection of not only defects in the skin of the fruits but also their association to certain diseases of particular importance. In the research works that use this technology, wavelengths that play a significant role in detecting some of these dangerous diseases are found, leading to the development of multispectral imaging systems that can be used in industry. This article reviews recent works that use colour and non-standard computer vision systems for the automated inspection of citrus. It explains the different technologies available to acquire the images and their use for the non-destructive inspection of internal and external features of these fruits. Particular attention is paid to inspection for the early detection of some dangerous diseases like citrus canker, black spot, decay or citrus Huanglongbing.     

Primary structure of water buffalo alpha-lactalbumin variants A and B

A novel electrophoretic alpha-lactalbumin (alpha-la) variant was detected in the Italian water buffalo breed. The isoelectric point of the variant, labelled A, was lower than the most frequent variant B. It presented an allelic frequency of 0.5% compared with the 97.1% of the BB allele. From Liquid Chromatography-Electrospray Ionization/Mass spectrometry, the molecular mass of the two alpha-la A and B variants were measured as 14,235.1+/-0.8 and 14,236.1+/-0.9 Da, respectively. The two proteins were sequenced and differentiated from one another by a single amino acid substitution, Asn45(B)-->Asp45(A). As this amino acid substitution altered the N-glycosylation sequence consensus Asn45-X-Ser46 it may be deduced that the protein glycosylation level of the alpha-la A would decrease.