Microbiological Deterioration Research Articles

Degradation of Concrete Cement Stone Under the Influence of Aspergillus niger Fungi

The concepts of physical and chemical transformations occurring in cement concrete under conditions of microbiological deterioration can be used to control the processes of the destruction of cement concretes in order to ensure the required durability and to predict the service life of products. The study of changes in the structural and phase composition of cement stone made of Portland cement grade CEM I 42.5N in the process of fungal deterioration for 6 months when moistened, as well as a sample of a concrete wall exposed to fungal microorganisms for 20 years, was carried out. Diffractograms of the studied cement stone samples contain a large number of pronounced narrow peaks and indicate a highly crystalline structure of phases with the presence of an X-ray amorphous phase of calcium hydrosilicates and tobermorite gel in the cement stone. Changes in the structure of cement stone under the influence of fungi are confirmed by the data of a derivatographic analysis. A decrease in the content of calcium hydrosilicates and ettringite, as well as other crystalline phases in cement stone, leads to a decrease in compressive strength by about 15% over 6 months of fungal degradation. Similar changes after 20 years of exposure to microorganisms suggest deterioration in the strength characteristics of concrete.

Effect of Packaging Methods and Storage Temperatures on the Quality of Erzurum Cheese Halva

Erzurum cheese halva is a traditional food registered with a geographical indication with its own taste and flavor, which is produced with saltless fresh civil cheese, fresh cream and flour mixture. This study was conducted to investigate the changes in the physical, chemical and microbiological properties of Erzurum cheese halva in different packaging and storage tempareture. The produced cheese halva samples were stored for two months in two different packaging methods (aerobic and vacuum packaged) and at three different storage temperatures (room temperature, +4℃ and -18℃). Some microbiological, chemical, physicochemical and sensory analysis of cheese halva samples were investigated during storage period. Furthermore, the dry matter, ash, protein, fat, salt and aw contents of cheese halva samples were determined on the 0th day of storage. The most obvious sign of deterioration were moldiness on aerobic packaged samples both the room temperature and +4℃ stored, and they were spoiled on the10th and 15th day of storage, respectively. It was observed that the acidity has increased and consumability has decreased in vacuum packaged samples stored at +4°C. Although neither chemical nor microbiological deterioration occurred in the vacuum packaged cheese halva samples stored on -18°C, negatively affects in the fibrous structure of the product and reduces the overall acceptability of the product. For this reason, future studies must be carried out that is necessary to search for more suitable packaging methods (e.g. modified atmosphere packaging) to protect the product's typical textural structure during the shelf life.

Evaluation of the Effects of Edible Coatings of Ocimum sanctum and Aloe vera on Jaggery Shelf Life

Background: In western Uttar Pradesh, jaggery is a widespread cottage enterprise based on agriculture, and farmers are forced to sell their product at a lesser price when it is still fresh. Therefore, it was thought to be desirable to create better storage techniques in order to extend its shelf life. Aloe vera, and Ocimum sanctum, often known as "Tulsi," are frequently utilised as antimicrobial food additives because they offer a host of other health advantages in addition to their well-known antibacterial qualities. Because the edible coatings made of these herbs provide a semi-permeable barrier to gases and water vapours, they may prolong the shelf life of jaggery by preventing degradation. Objective: The goal of the current study was to assess the ability of edible coatings of common Indian herbs, such as tulsi and Aloe vera,, to extend the shelf life of jaggery while maintaining attributes that are equal to those of fresh jaggery, in accordance with the guidelines set forth by the Food Safety and Standards Authority of India (FSSAI). Methodology: The physicochemical characteristics, antioxidant activity, total viable count, and antibacterial activity of tulsi-Aloe vera, coated (TAC), Ocimum sanctum, and Aloe vera, (AC) jaggery were assessed and compared with non-coated control. The physicochemical properties were ascertained using standard methodology for measurement of reducing sugars, proteins, phenols, saponins, tannin, alkaloids, and flavonoids. The antimicrobial activity was ascertained by means of the agar double diffusion method. According to established protocol, antioxidant activity was assessed using the DPPH radical scavenging assay and the reducing power assay. Results: According to the research, there is no discernible microbiological deterioration and the edible coatings containing tulsi and Aloe vera, extend the shelf life of jaggery during storage. When compared to uncoated jaggery, coatings were efficient at preventing the growth of both Gramme positive and Gramme negative microorganisms. Over the course of six months, the herb-infused coatings also retained their phenolic, flavonoid, and tannin contents, which improved their anti-oxidant efficacy when compared to the untreated control group.

Effects of carbon dioxide concentration in modified atmosphere packaging on the shelf life and quality criteria of whole wheat bread during storage

AbstractThis study aimed to determine the effects of carbon dioxide concentration in modified atmosphere packaging (MAP) on the quality criteria and shelf life of whole wheat flour bread. Four different concentrations of CO2 and N2 gases (30% CO2 + 70% N2, 50% CO2 + 50% N2, 70% CO2:30% N2 and 100% CO2) were applied to the bread samples, which were packaged with PA/EVOH/LDPE (polyamide/ethylene vinyl alcohol/low‐density polyethylene). The samples were stored at room temperature (25°C ± 1°C) for 13 days. The control group was packaged using BOPP (bi‐oriented polypropylene) under atmospheric air as in traditional current use. The effects of MAP on headspace gas analysis, pH, moisture content, water activity, water‐holding capacity, blue value, hardness, total mould and yeast count and sensory evaluation were analysed on days 0, 3, 4, 5, 7, 10 and 13. The results showed that the most effective gas combination in extending the shelf life of whole wheat bread was 100% CO2, and its shelf life was 10 days, whereas it was only 3 days for the control group. Increasing concentrations of CO2 significantly affected mould and yeast growth. As the CO2 concentration increased, the bread exhibited higher water‐holding capacity and blue values, which are important indicators for bread staling. An improved preservation of sensory properties was observed in proportion to increasing CO2 concentrations. However, the CO2 gas concentration did not affect the hardness of the bread. Overall, the study suggests that MAP technology, particularly using 100% CO2, can effectively extend the shelf life of whole wheat flour bread without the need for preservatives, not only extending the microbiological shelf life but also increasing the sensory shelf life. The species that grew in air‐packaged samples were suppressed under modified atmosphere conditions and chalk mould fungi were the dominant and shelf life‐impacting species in the MAP samples. These findings could be beneficial in reducing bread wastage, which is a critical issue in today's society due to the limited shelf life of bread caused by rapid microbiological deterioration or staling.

Application of fuzzy model for the shelf-life determination of whole sea bass (Dicentrarchus labrax) under refrigerated temperatures

In this study, microbiological deterioration of whole sea bass stored at refrigerator temperatures (4°C) was determined through fuzzy modeling. Total Mesophilic Aerobic Bacteria (TMAB), Total Psychrophilic Aerobic Bacteria (TPAB), Lactic Acid Bacteria (LAB), Pseudomonas sp., and Enterobacteriaceae counts were observed during 12 days of storage. Quality Index Method (QIM) was used for sensory analysis of the samples and shelf life was determined according to sensory deterioration. The growth of the microorganisms was statistically significant (p<0.05) at the end of the storage period. Additionally, significant differences (p<0.05) were observed for QI scores after the 8th day of the storage in whole sea bass stored under refrigerated conditions. A total of 12 rules were determined in the fuzzy logic application. Mamdani was used as the fuzzy type for fuzzy modeling, and centroid was used as the defuzzification method. Fuzzy membership values were computed using triangular membership functions. According to the research results, the shelf life of sea bass fish was determined as 8 days from the time of 12 days storage. As a result, it was observed that the sensory score could be determined by using Fuzzy logic (R2=0.96) according to microbiological parameters in sea bass stored in refrigerator conditions. In this context, it was concluded that Fuzzy logic could be used in shelf-life estimation in seafood products.

Gastropods as a source for fecal indicator bacteria in drinking water

Microbial water quality is routinely examined using the fecal indicator bacteria Escherichia coli, coliform bacteria and enterococci. Several practical cases in German drinking water distribution systems indicated invertebrates such as insects or gastropods as a source for the microbiological deterioration. Therefore, we examined three genera of Gastropoda (Arion, Helix and Cepaea) for the presence of fecal indictor bacteria in excreta using standard methods. Enterococci and coliform bacteria were detected in high concentrations (mean values of 1.5 × 106 and 6.3 × 106 per gram feces, respectively). E. coli was also detected, still specification revealed that what was assigned by standard ISO-methods to be E. coli was indeed a novel species of Buttiauxella, exhibiting β-D-glucuronidase activity, thus, explaining the false-positive results. Microbiome analyses confirmed the cultural results. Enterobacteriaceae were dominant in the samples, yet only very few sequences could be assigned to Escherichia. Our study suggests, that enterococci and coliform bacteria are an integral component in the gastropod microbiome, whereas E. coli might be derived from other sources with gastropods being a vector. The results further indicate, that the current concept of fecal indicator bacteria needs to be extended, as not only humans and homeothermic animals could be a source for fecal indictor bacteria, but also gastropods need to be taken into consideration.

Imaging and micro-invasive analyses of black stains on the passepartout of Codex Atlanticus Folio 843 by Leonardo da Vinci

This paper accounts for the diagnostic campaign aimed at understanding the phenomenon of black stains appeared on the passepartout close to the margins of Folio 843 of Leonardo da Vinci’s Codex Atlanticus. Previous studies excluded microbiological deterioration processes. The study is based on a multi-analytical approach, including non-invasive imaging measurements of the folio, micro-imaging and synchrotron spectroscopy investigations of passepartout fragments at different magnifications and spectral ranges. Photoluminescence hyperspectral and lifetime imaging highlighted that black stains are not composed of fluorescent materials. μATR-FTIR imaging of fragments from the passepartout revealed the presence of a mixture of starch and PVAc glues localized only in the stained areas close to the margin of the folio. FE-SEM observations showed that the dark stains are localized inside cavities formed among cellulose fibers, where an accumulation of inorganic roundish particles (∅100–200 nm in diameter size), composed of Hg and S, was detected. Finally, by employing synchrotron μXRF, μXANES and HR-XRD analyses it was possible to identify these particles as metacinnabar (β-HgS). Further research is needed to assess the chemical process leading to the metacinnabar formation in the controlled conservation condition of Leonardo’s Codex.

Effects of UV-C Irradiation and Vacuum Sealing on the Shelf-Life of Beef, Chicken and Salmon Fillets.

One-third of the world's food supply is lost, with meat being a major contributor to this loss. Globally, around 23% of all meat and 35% of all seafood products are lost or wasted. Meats and seafood products are susceptible to microbial spoilage during processing, storage, and distribution, where microbial contamination causes significant losses throughout the supply chain. This study examined the efficacy of UV-C irradiation and vacuum-sealing in preventing microbiological deterioration in beef, chicken, and salmon fillets. The samples were sterilized using a constant UV-C irradiation dose of 360 J/m2 and stored under a reduced pressure of 40 kPa. A microbiological analysis was conducted daily to examine the microbial contamination, which included counting the colonies of Pseudomonas spp., aerobic bacteria, lactic acid bacteria (LAB), Salmonella, and Escherichia coli, as well as monitoring the increase in pH levels. The results demonstrated a statistically significant difference (p > 0.05) in the aerobic bacteria counts between the storage conditions and storage days in all samples, which is a primary indicator of microbial spoilage. In contrast, the differences varied in the Pseudomonas spp. and LAB counts between the storage conditions and storage days, and there was no significant difference (p < 0.05) in the pH levels between the storage conditions. The results indicate that the combination of UV-C irradiation and vacuum sealing effectively inhibits microbial growth and extends the shelf-life of beef, chicken, and salmon fillets by 66.6%.

The Effect of Nonthermal Pretreatment on the Drying Kinetics and Quality of Black Garlic.

Black garlic is obtained from regular garlic (Allium sativum L.) through the aging process and consequently gains many health-promoting properties, including antidiabetic and antioxidant. However, the material is still prone to microbiological deterioration and requires a long time to dry due to its properties. Therefore, this study aimed to investigate the effect of various drying methods on the quality of black garlic as well as determine the influence of selected nonthermal pretreatments on the drying kinetics and quality of black garlic, which is especially important in the case of the materials that are difficult to dry. The Weibull model was chosen to describe drying kinetics. Additionally, color, water activity together with antioxidant activity, phenolic compounds, and antidiabetic potential were determined. This study found that the application of a pulsed electric field (PEF), a constant electric field (CEF) as well as a magnetic field (MF) significantly reduced the time of drying (by 32, 40, and 24 min for a PEF, a CEF, and a MF, respectively, compared to combined drying without the pretreatment), and resulted in high antidiabetic potential. However, the highest content of phenolic compounds (1123.54 and 1125.36 mg/100 g dm for VMD125 and CD3h-VMD, respectively) and antioxidant capacity (ABTS = 6.05 and 5.06 mmol Trolox/100 g dm for VMD500 and CD6h-VMD, respectively) were reported for black garlic treated by vacuum-microwave drying and combined convective pre-drying followed by vacuum-microwave drying. Overall, the nonthermal pretreatment decreased the time of drying and showed very good efficiency in maintaining the antidiabetic potential of black garlic, especially in the case of the materials pretreated by a constant electric field (IC50 = 99 and 56 mg/mL, for α-amylase and α-glucosidase, respectively).

Application of water-honey extract of St. John’s wort herb to improve biotechnological and rheological properties of wheat dough

Experimental studies of the effect of water-honey extract of St. John's wort grass fermented by lactic acid bacteria Str.lactis and Str.cremoris on microorganisms causing microbiological deterioration of wheat flour bakery products showed a positive effect of the introduced component on the rheological and biotechnological parameters of wheat dough. By adding additional nutrients that activate the vital activity of the fermenting microflora, the gas-forming ability of the dough increased by 20%, the fermentation activity improved by 35%, and the desired dough acidity of 3.0 deg. was reached within 120 minutes, i.e. the fermentation process reduced by 60 minutes.

Application of soluble gas stabilization technology on ready-to-eat pre-rigor filleted Atlantic salmon (Salmo salar L.).

The demand for high‐quality, convenient, and sustainable salmon products represents a potential for value‐added product development and novel packaging solutions. Soluble gas stabilization (SGS) technology, which applies dissolved CO2 in the product before packaging, represents a novel approach to retain product quality and prevent microbiological deterioration during cold storage of pre‐rigor filleted salmon loins.The present study aimed to examine the solubility of CO2 in salmon loins as affected by rigor status. In addition, the effect of predissolved CO2 on the overall quality of pre‐rigor vacuum‐packed Atlantic salmon (Salmo salar L.) was investigated during storage at 4°C. The CO2 pretreatment was conducted, exposing loins to 100% CO2 for 18 h at 4°C (the control group was kept in air at 4°C) before repackaging and storage for 15 days.Dissolved CO2 in the muscle (equilibrium achieved four days post packaging) was slightly higher in pre‐rigor than post‐rigor salmon loins (p equilibrium = 0.006). Moreover, the overall spoilage (Hvalue) and microbiological stability of salmon fillets stored in SGS‐vacuum were significantly improved compared to vacuum‐packed loins (p < 0.05).The results demonstrate that SGS technology can maintain the overall quality of pre‐rigor vacuum‐packed salmon loins without introducing the high gas‐to‐product volume ratio recognized by modified atmosphere packaging. Thus, the application of SGS technology on pre‐rigor loins can lead to higher economic gain and environmental benefits due to the reduced amount of required packaging material and reduced food waste.Practical ApplicationCO2 can be dissolved in pre‐rigor salmon loins before vacuum packaging to increase product shelf life during cold storage.

Biodegradation Study of Polyurethanes from Linseed and Passion Fruit Oils

Bio-based polyurethanes (PU) have been developed as biodegradable and biocompatible, promising materials. In this work, PU foams with interesting properties and biodegradable characteristics were prepared from the polyols of linseed oil (LO) and passion fruit oil (PFO). The PUs reported herein were synthesized in 0.8 and 1.2 [NCO]/[OH] molar ratios, and were submitted to a soil degradation test, followed by analyses via scanning electron microscopy (SEM), stereomicroscope, thermogravimetry (TG/DTG), and Fourier transform infra-red (FTIR) spectroscopy. The results obtained indicate significant biodegradation activity. SEM micrographs of the PUs after soil the degradation test showed that the materials were susceptible to microbiological deterioration. TG/DTG curves showed that the PU samples were less thermally stable after the period of landfill than those freshly prepared. FTIR spectroscopy was used to identify chemical changes that occurred during biodegradation.

Evaluation of the efficiency of nanoparticles for increasing α-amylase enzyme activity for removing starch stain from paper artifacts

Starch stain is a common stain on paper artifacts. This stain leads to deformation of the surface of the paper and promotes the growth of microbiological deterioration. This study aims to use nanoparticles with an α-amylase enzyme to improve its quality for removing this type of stain from the surface of paper artifacts. Accelerated heat aging was used on starch stain applied on the new paper samples. The α-amylase enzyme was prepared. Silver and gold nanoparticles were biosynthesized by local fungal isolation. The produced silver and gold nanoparticles were characterized by using different techniques of analysis (UV- Visible spectroscopy, Transmission Electron Microscope (TEM), and X-Ray diffraction (XRD) analysis). Different concentrations of Ag-NPs and Au-NPs were added to the α-amylase reaction mixture to enhance its activity for removing starch stains. Some analytical techniques were also used for the evaluation of the efficiency of α-amylase and nanoparticles for removing starch stains (Color measurement, Scanning Electron Microscope (SEM), and pH measurement). The results proved that Ag-NPs at 20 microliters increased the activity to about 160%, whereas Au-NPs enhanced the activity to about 140% at a concentration of 5μL. The results showed that α-amylase enzyme incorporated with Ag-NPs exhibited better results more than its use alone. The addition of Ag-NPs to α-amylase enzyme for the removal of starch stain reduced the total color differences, improved the surface morphology.

Green synthesis of silver nanoparticles with Euphorbia tirucalli extract and its protection against microbial decay of strawberries during storage.

Silver nanoparticles (AgNPs) can be produced through an easy and safe process called green synthesis and have been considered an efficient antimicrobial agent. The antimicrobial effect of silver nanoparticles green synthesized with E. tirucalli (aveloz) can be a promising technique for preserving stored strawberries. The objective of this work was to perform a green synthesis of AgNPs with aveloz extract (Av) and evaluate its effect on the physiology and preservation of stored strawberries. Silver nitrate was reduced with Av to produce Av-AgNPs. The Av-AgNPs were characterized by Scanning Electron Microscope, Energy Dispersive X-ray Spectrometry, and laser diffraction. The in vitro antifungal activity of Av-AgNPs was evaluated against Botrytis cinerea and Rhizopus stolonifer. Strawberries were treated with Av-AgNPs and stored (5°C) for 12days. Respiratory rate, decay, fresh mass loss, firmness, total phenolics and antioxidant activity of the strawberries were evaluated. According to the results, Av-AgNPs synthesis was performed, and it presented sizes between 40 and 90nm. Av-AgNPs inhibited B. cinerea but was less effective for R. stolonifer. Total phenolic compounds, antioxidant activity, fresh mass loss and firmness of strawberries were not influenced by Av-AgNPs. Treated strawberries had a lower respiratory rate than the control and showed no symptoms of microbiological deterioration until 9days of storage, while in the control the deterioration symptoms started after 3days. This study showed that the green synthesis of AgNPs with Av produced nanoparticles smaller than 100nm, and that they were effective against strawberries decay during storage, indicating to be a promising protection technique against decay.

Pinhão coat extract encapsulated in starch ultrafine fibers: Thermal, antioxidant, and antimicrobial properties and in vitro biological digestion

This study aimed to produce soluble potato starch ultrafine fibers for the encapsulation of pinhão coat extract (PCE), evaluating their relative crystallinity (RC), thermal stability, antioxidant activity, antimicrobial activity against Escherichia coli and Staphylococcus aureus, as well as in vitro biological digestion. In the simulation of in vitro biological digestion, the phenolic compounds release profile was also evaluated. The ultrafine fibers were produced by electrospinning, based on a polymeric solution composed of soluble potato starch (50% w/v) and formic acid. Then, PCE was incorporated at various concentrations (0.5%, 1.0%, and 1.5%, w/w, dry basis). The endothermic event of free PCE was not observed in the ultrafine fibers, which suggests its encapsulation. The RC decreased according to the increase in PCE concentration in the ultrafine fibers. The PCE resisted thermal treatments when encapsulated into the ultrafine fibers (100 and 180°C), and the ultrafine fibers with 1% PCE presented the highest amount of preserved phenolic compounds. Regarding antioxidant activity, the free PCE presented 85% of DPPH inhibition and the ultrafine fibers had 18% inhibition, not differing among the PCE concentrations (p<0.05). The free PCE and the ultrafine fibers with 0.5% PCE showed inhibitory effect against S. aureus and the ones with 1.5% PCE showed controlled release of phenolic compounds during the simulation of in vitro digestion. Starch ultrafine fibers showed potential to be applied in food industries due to their capacity of protecting phenolic compounds when submitted to high temperatures or gastrointestinal conditions. Nevertheless, their application depends on the end use of the product. PRACTICAL APPLICATION: The encapsulation of pinhão coat extract (PCE) in ultrafine starch fibers promotes greater preservation of phenolic compounds. Thus, it can be incorporated into different foods that are produced using the ultra-high temperature (UHT) process-at 135-145°C for 5 to 10 s, or some other equivalent time/temperature combination. Another possibility is the incorporation of ultrafine fibers in active packaging: compounds can migrate to food, improving sensory characteristics, increasing shelf life, preventing chemical and microbiological deterioration, and ensuring food safety.

Prospects of application of ultrasonic processing of half-finished products in baking technology

The food industry has a very wide range of methods and means of influencing raw materials to give them the required technological properties. One of the prospective and effective physical methods of processing raw materials and food products, according to a number of studies, is ultrasound, which helps to increase productivity, reduce energy costs, improve the quality of finished products, extend shelf life, and most importantly, ensure safe and minimally processed products. To prevent microbiological deterioration, the products are subjected to various treatments, the main of which is the effect of low temperatures (cooling, freezing) or high temperatures (pasteurization, sterilization). However, these methods either slow down microbiological processes or reduce the nutritional and biological value. In this regard, the study of innovative methods that guarantee the consumer safe and minimally processed products, one of which is the method of ultrasound processing becomes particularly relevant. The impact of ultrasonic waves on physical and chemical processes occurring during the cooling process can improve the quality of the finished product, increase storage time, reduce energy consumption and create products with new consumer properties.

Lime juice and enzymes in clean label pan bread: baking quality and preservative effect.

Clean label breadmaking is a challenge for the bakery industry, considering the removal of additives, especially preservatives. Through dough acidification and theuse of enzymes, shelf-life of breads may be extended in terms of sensory quality and preservation against microbiological deterioration. This study aimed to evaluate the effect of lime juice (0, 10.2 or 20.4g.100g-1, flour basis, f.b.) on technological characteristics and preservation of clean label pan breads, with and without enzymes (0.0015 and 0.0050g.100g-1 of phospholipase and fungal xylanase, f.b., respectively). The technological parameters of dough (high-speed mixing time, temperature, pH before and after proofing) and pan bread (specific volume, firmness, crust and crumb color, aw, pH and mold occurrence) were evaluated. Doughs with lime juice required a longer mixing time, and produced breads with lower volume, firmer crumb, lighter crust and lower mold occurrence, when compared to the market standard. Pan breads with 10.2g.100g-1 of lime juice and enzymes showed a higher volume and softer crumb, compared to those with only lime juice. Thus, the joint use of lime juice and enzymes may be suitable for clean label pan breads, maintaining a soft crumb and longer shelf life without additives.

Changes in chemical and microbiological quality of semi-processed black soldier fly (Hermetia illucens L.) larval meal during storage

Edible insects are receiving attention as a protein source in the food and feed sector. However, successful commercialisation requires mass production matched with appropriate processing and storage techniques. The quality of dried and pulverised black soldier fly larvae stored in woven polypropylene (PP) sacks, polyethylene (PE) bags and plastic containers with screw lid (PL) in ambient and refrigerated environments was monitored over six months. Chemical indicators (oxidation, fatty acid profile), microbiological parameters (total viable counts, yeast and moulds,Enterobacteriaceae, presumptive coliforms,Salmonella) and colour change were examined. Temperature and relative humidity of the storage environments were monitored. In the ambient environment (temperature: 23.6±2.7 °C; relative humidity: 57.6±7.0%), chemical deterioration progressed 1.5 and 1.2 times faster in PP and PE, respectively, compared to PL. Refrigeration (temperature: 5.4±1.1 °C; relative humidity: 97±5.7%) exacerbated spoilage in the PP due to permeation of moisture through the woven strands, but slowed chemical deterioration by factors of 3.3 (PL) and 2.8 (PE). Likewise, based on the average counts ofEnterobacteriaceae and yeast and moulds, microbiological deterioration progressed 2.1 and 1.4 times faster in the PP and PE, respectively, while refrigeration retarded build-up of microbial loads by factors of 1.3-9.6. The presence ofSalmonella spp. in the experimental product indicates that due attention must be given to adequacy of processing and handling procedures for dried black soldier fly meal.

Hydrophobic Zinc Oxide Nanocomposites for Consolidation and Protection of Quartzite Sculptures: A Case Study

Quartzite sculptures are considered some of the most impressive and informative archaeological remains which have been found in the most of Egyptian archaeological sites. Regrettably, quartzite sculptures suffer from many deterioration aspects such as granular disintegration, scaling, cracking, efflorescence, soiling, microbiological colonization. Water is the main aggressive deterioration factor of stones and stone-based monuments, as in addition to its direct role in deterioration mechanisms, it plays as a catalyst in the physicochemical and microbiological deterioration processes.During the last two decades, polymer nanocomposites have widely been applied in the field of cultural heritage conservation due to their unique physical and chemical characteristics. Zinc oxide nanoparticles are among the most important semiconductive nanomaterials that have been applied in the fabrication of nanocomposites. They have been demonstrated to improve the physicochemical and mechanical properties of polymers. In addition, zinc oxide nanoparticles were mixed with polymers in order to fabricate superhydrophobic and self-cleaning protective materials.The aim of this paper is to evaluate the efficiency of zinc oxide nanocomposites, in order to select the best of them for the consolidation and protection of a colossal quartzite statue of Ramesses II. The properties of the treated quartzite samples were comparatively examined by colourimetric measurements, static water contact angle, compressive strength, and scanning electron microscope.

KERUSAKAN PASCAPANEN PADA UBI KAYU HASIL PEMULIAAN SELAMA PENYIMPANAN

Postharvest deterioration is a major problem which is an obstacle for cassava handling both for conventional cassava variety and mutant variety. There are two types of postharvest deterioration on cassava, namely postharvest primary deterioration (PPD) or primer deterioration of physiological deterioration, and microbiological deterioration. Damage can be minimized by carrying out storage in optimal conditions. This study aimed to determine the level of postharvest deterioration on cassava variety R and U during 35 days of storage. The storage treatment was storage consist of 1) wooden boxes and moist sawdust storage (P1) and 2)control storage (P2). The results indicated that RP2 and UP2 produced physiological deterioration by 25% on the 7th day of storage and reached 100% on the 35th day of storage. Meanwhile, the percentage of microbiological deterioration reached more than 20% on the 14th day of storage. On the other hand, RP1 and RP2 indicated good results. Both varieties experienced only less than 25% physiological deterioration and did not experience microbiological deterioration during storage.