Physical Properties of Climbing Black Pepper (Piper nigrum) and Alligator Pepper (Aframomum melanguata) as Affected by Dehydration

This study was conducted to determine effect of drying temperature and duration on selected physical properties of climbing black pepper (Piper nigrum) and alligator pepper (Aframomum melanguata) using response surface approach. Drying temperature (55.86, 60, 70, 80, 84.14 °C) and duration (2.59, 3, 4, 5, 5.414 hours) were variables while size (length, breadth, thickness), mass, sphericity, aspect ratio, moisture content, moisture loss, colour and bulk density were responses. Mass, density and moisture loss of climbing pepper were significantly affected by drying temperature and duration at 5% level of significance. Other climbing pepper physical properties under study were not influenced significantly. All alligator pepper properties considered were not significant (p > 0.05). Climbing pepper mass, density and moisture loss varied between 1.55 to 6.37 g, 0.17 to 0.59 g/ml and 31.1 to 84.0% respectively.     

Dielectric Properties of Red Pepper Powder Related to Radiofrequency and Microwave Drying

To provide useful information for drying red pepper with radiofrequency or microwave energy and designing dielectric drying equipment, dielectric properties (dielectric constant ε′ and loss factor ε?″) of red pepper powder with moisture contents ranging from 10.4 to 30.8 % wet basis were measured at different temperatures (from 25 to 85 °C) over a frequency range of 20–4,500 MHz with a vector network analyzer and an open-ended coaxial-line probe. The results showed that both ε′ and ε?″ of red pepper powder were dependent on electromagnetic wave frequency, moisture content, and temperature. The value of ε′ decreased with increases in frequency over the tested range. The ε?″ decreased with increasing frequency when the frequency was below 4,000 MHz, and increased slightly when it was above 4,000 MHz. Both ε′ and ε?″ increased as either moisture content or temperature increased, and the increases were a little greater at high moisture and temperature than those at low moisture and temperature. The moisture- and temperature-dependent permittivities of red pepper powder at several frequencies of interest could be described by quadratic models. The results of variance analysis exhibited that both moisture content and temperature had significant influence (p<0.01) on permittivities of red pepper powder. The power penetration decreased as frequency, moisture content, and temperature increased. Large penetration depth at radiofrequencies below 100 MHz could be used to dry red peppers in a large scale, while microwave energy could be used for drying red peppers in a small scale.     

Correlation of total ergosterol levels in stored canola with fungal deterioration

Deterioration of canola caused by fungal growth during storage is a problem at moisture contents exceeding 8%. Secondary indicators of fungal growth, such as ergosterol, the main sterol found in fungal cell membranes, offer a way of relating fungal biomass to deterioration. The objective of this research was to determine ergosterol accumulation in stored canola and to correlate it with seed deterioration measured by germination, fungal infection, fat acidity values (FAV), and carbon dioxide production. Total ergosterol levels increased with storage time, temperature, and seed moisture content. Aggressive and destructive fungal species such as Aspergillus candidus and Penicillium spp. contributed more to ergosterol than Eurotium spp. Initial total ergosterol concentrations between 1.46 and 1.67 ppm may be taken as the background levels in sound canola, and levels greater than 2 ppm were related to significant levels of spoilage. Results showed that germination and FAV had a strong correlation with total ergosterol (Spearman rank order correlation coefficients of −0.826 and 0.800, respectively) but the relationship was weaker for CO₂ production (Spearman rank order correlation coefficient of 0.650).     

Effect of γ-irradiation on antioxidant activity of black pepper (Piper nigrum L.)

Antioxidant activity and EPR investigations of irradiated ground black pepper (Piper nigrum L.) were evaluated. The black pepper was exposed to γ-irradiation at doses from 5 to 30 kGy. The effect of irradiation on antioxidant properties of black pepper extracts was investigated by radical-scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, by determination of reducing power and content of thiobarbituric acid-reactive substances. Some significant changes were observed in creation of thiobarbituric acid-reactive substances (TBARS). Difference between non-irradiated and irradiated samples at the legal European limit dose of 10 kGy reached, on average, 23% and, at the Food and Drug Administration (FDA) 30 kGy limit, 33%. Irradiation affected significantly the DPPH radical-scavenging activity and reducing power of ground black pepper extracts. The γ-radiation treatment of ground black pepper samples observed by EPR, resulted in the production of three paramagnetic species (GI–GIII) characterized by different origin, thermal behaviour and stability. The axially symmetric EPR resonances, GI and GII, were assigned to the carbohydrate radical structures. The spin Hamiltonian parameters of GIII possessed the characteristic features of “cellulosic” radical species. The EPR measurements, performed 20 weeks after the radiation process, confirmed that temperature increase from 298 to 353 K, caused significant decrease of integral EPR signal intensity for γ-irradiated samples (∼40%), compared to the reference (non-irradiated) ground black pepper, where only 13% drop was found. Significant correlation between EPR and thiobarbituric acid methods was assessed by study of antioxidant activity changes in relation to irradiation doses and also in the case of spice storage, between EPR and reducing power methods.     

Microbial decontamination of black pepper by ozone and the effect of the treatment on volatile oil constituents of the spice

The use of ozone as a substitute for ethylene oxide to decontaminate whole black peppercorn and ground black pepper and the effects of ozone on the volatile oil constituents of the spice were studied. Black peppercorns were immersed in water and sparged with ozonised air (ozone concentration, 6·7 mg litre^?1) for 10 min at an air flow rate of 6 litre min^?1. This treatment reduced the microbial population of peppercorn by 3–4 log numbers. Ground black pepper with various moisture levels was sparged with ozonised air for up to 6 h. This treatment reduced the microbial population by 3–6 log numbers, depending on the moisture content of the spice. Higher moisture content led to a greater reduction in microbial load. The volatile oil constituents of the spice with and without ozone treatment were extracted with isopropyl ether and analysed by gas chromatography and gas chromatography-mass spectrometry. Ozone treatment of ground black pepper resulted in the oxidation of certain volatile oil constituents while the treatment had no significant effect on the volatile oil constituents of whole peppercorn.     

Impact of opening hermetic storage bags on grain quality,fungal growth and aflatoxin accumulation

Purdue Improved Crop Storage (PICS) bags are used by farmers in Sub-Saharan Africa for pest management of stored grains and products, including maize. These bags hermetically seal the products, preventing exchange with external moisture and gases. Biological respiration within the bags create an environment that is unsuitable for insect development and fungal growth. This study was conducted to determine the impact of routine opening of the storage bags for maize consumption on fungal growth and aflatoxin contamination. Maize with moisture contents (MC) high enough to support fungal growth (15%, 16%, 18% and 20%) was stored in PICS bags, which were opened weekly and exposed to humid conditions (85% RH) for 30 min over a period of 8 weeks and 24 weeks. Monitors indicated that oxygen defused into the open bags but did not reach equilibrium with the bottom layers of grain during the 30-min exposure period. Fungal colony forming units obtained from the grain surface increased 3-fold (at 15% MC) to 10,000-fold (at 20% MC) after 8 weeks. At both 8 weeks and 24 weeks, aflatoxin was detected in at least one bag at each grain moisture, suggesting that aflatoxin contamination spread from a planted source of A. flavus-colonized grain to non-inoculated grain. The results indicate that repeatedly breaking the hermetic seal of the PICS bags will increase fungal growth and the risk of aflatoxin contamination, especially in maize stored at high moisture content. This work also further demonstrates that maize should be properly dried prior to storage in PICS bags.     

Degradation of the natural mutagenic compound safrole in spices by cooking and irradiation

Safrole was determined using gas-liquid chromatography in some common spices as star anise, cumin, black pepper and ginger. Safrole concentration in these spices was 9325, 3432, 955 and 500 mg · kg^?1, respectively. Black pepper was chosen to use in the following experiments. Using Ames-test with Salmonella TA 98 and TA 100 proved high cytotoxic effects due to pure safrole and black pepper volatile oil in both of them. The degradation of safrole was obvious after drying of the washed seeds of black pepper especially at 70 °C for 30 min or with sun-drying. Also, high irradiation doses (20 and 30 kGy) caused high degradation of more than 90% of the initial toxic concentration in black pepper. Whereas, microwave caused same effects at 75 s, but unfortunately, the powder was burned due to moisture absence. Boiling whole seeds or powder of black pepper during cooking for few minutes (1-5 min) were more efficient in decreasing safrole content. Finally, these results proved that the mutagenicity of some spices due to presence of safrole can be destructed during drying of the washed seeds or during cooking either with or without any additional treatment as irradiation. But irradiation of these spices became more necessary for using in some food industries as milk products to get more safe for human consumption.     

Synthesis and Characterization of Nano‐Encapsulated Black Pepper Oleoresin using Hydroxypropyl Beta‐Cyclodextrin for Antioxidant and Antimicrobial Applications

Previous studies have reported antimicrobial and antioxidant activity of black pepper oleoresin which is associated to its phenolic compounds and piperine. The ability of cyclodextrins to form an inclusion complex with a guest molecule could improve black pepper oleoresin application, bioavailability, and stability in foods. Hydroxypropyl beta‐cyclodextrin (HPBCD) inclusion complex with black pepper olereosin were synthesized using the kneading method and characterized for its physico‐chemical properties and its antioxidant and antimicrobial activities. Inclusion complex size was 103.9 ± 7.6 nm and indicated to be a polydisperse system. The entrapment efficiency was 78.3 ± 3.6%, which suggests that other constituents in black pepper oleoresin have higher affinities for HPBCD than piperine (major compound in black pepper oleoresin). Thermograms showed the disappearance of oxidation peaks of black pepper oleoresin, proving complex formation with HPBCD. Phase solubility results indicated 1:1 stoichiometric inclusion complex formation and an increase of black pepper oleoresin aqueous solubility with HPBCD concentration. Nano‐encapsulation with HPBCD did not affect (P > 0.05) total phenolic content; however, it enhanced (P < 0.05) black pepper oleoresin antioxidant activity. Black pepper oleoresin and its inclusion complex were analyzed for their antimicrobial activity against Escherichia coli K12 and Salmonella enterica serovar Typhimurium LT2. Both free and encapsulated black pepper oleoresin effectively inhibited bacterial growth within the concentration range tested. Black pepper oleoresin encapsulated in HPBCD was able to inhibit Salmonella at lower (P < 0.05) concentrations than its corresponding free extract. Therefore, black pepper oleoresin‐HPBCD nanocapsules could have important applications in the food industry as antimicrobial and antioxidant system.     

Comparison of deterioration of rye under two different storage regimes

Deterioration of stored rye samples was studied at different moisture contents and temperatures. Germination, presence of visible and invisible microflora, and free fatty acid values (FAV) were determined for samples at 10.0, 12.5, 15.0 and 17.5% moisture content (wet mass basis) stored at 10, 20, 30 and 40 °C for 16 weeks. Results of deterioration at constant moisture content (case 1) were compared with previously reported results for deterioration under declining moisture content (case 2). Germination rate was almost the same for all the moisture content samples stored at 10 °C for both cases, but a significant decrease was observed at other temperatures with high moisture content. Fatty acid values remained similar in both cases when rye was stored at 10 and 20 °C, whereas at 30 and 40 °C, FAVs of the rye samples in which the moisture content was maintained were high and increased with an increase in temperature and moisture content. Visible mould appeared early in the samples whose moisture content was maintained. Penicillium spp. and Aspergillus glaucus group were the predominant fungal species present in both the cases throughout the study. The rate of deterioration was significantly different between the two cases.     

Production of fungal lipases using wheat bran and soybean bran and incorporation of sugarcane bagasse as a co-substrate in solid-state fermentation

Fungal strains were screened for lipase producing activities and 10 strains were classified as good producers. Aspergillus sp., Fusarium sp., and Penicillium sp. exhibited the highest activities when fermented in wheat bran (WB) and soybean bran (SB). No fungal growth was observed using sugarcane bagasse (CB). An experimental design was applied to incorporate CB into the fermentation process for lipase production by Aspergillus sp. and Penicillium sp., and to evaluate the best moisture content for the substrate. Strains studied achieved maximum lipase activities with 25% CB combined with 75% WB or SB at 40% moisture content. The highest lipase activities were observed for WB and SB, and for SB combined with CB using Aspergillus sp. Fermentation of 96 h was the optimum period for enzyme production.     

Comparative effects of gamma and microwave irradiation on the quality of black pepper

Powdered black pepper from Egyptian markets, was irradiated with different recommended doses of gamma rays (5.0 and 10.0 kGy) and with microwaves for different periods (20, 40 and 75 s) to improve its hygienic quality. The most common bacterial isolates were of three generaBacillus, Clostridium andMicrococcus (7.5 × 10⁶), whereas the predominant fungi (7.8 × 10⁴) wereAspergillus species,A. glaucus, A. flavus, A. niger andA. ochraceus. Doses of gamma irradiation used (5.0 and 10 kGy) were sufficient to decrease spore-forming bacteria (SFB) and to inhibit the fungal flora and coliforms which contaminated the black pepper powder. Microwave treatments for 40 s and 75 s were of the same effectiveness whereas treatment for 20 s was less so. GLC analysis proved the presence of 31 peaks, only 19 compounds were identified as monoterpene hydrocarbons (56.21%), the major one being -phellandrene and limonene. Sesquiterpenes were also present, mainly -caryollphyllene (3.69%) as well as oxygenated compounds such as terpenol, geraniol, Me-chavicol, eugenol and anisol. Gamma irradiation at 5 kGy and 10 kGy respectively decreased the numbers of identified compounds from 21 (86.58% concentration) in untreated pepper to 16 (59.22% concentration), 15 (54.06% concentration). In comparison, microwave treatments, particularly for 40 s and 75 s, increased the concentration of the same compounds. The results obtained indicate that microwave treatment, under these conditions, is a safe and suitable technique for decontamination of black pepper which does not result in a great loss of flavour compounds, as compared with recommended doses of gamma irradiation.     

Growth and survival of Salmonella in ground black pepper (Piper nigrum)

A four serovar cocktail of Salmonella was inoculated into ground black pepper (Piper nigrum) at different water activity (a_w) levels at a starting level of 4–5 log cfu/g and incubated at 25 and at 35 °C. At 35 °C and a_w of 0.9886 ± 0.0006, the generation time in ground black pepper was 31 ± 3 min with a lag time of 4 ± 1 h. Growth at 25 °C had a longer lag, but generation time was not statistically different from growth at 35 °C. The a_w threshold for growth was determined to be 0.9793 ± 0.0027 at 35 °C. To determine survival during storage conditions, ground black pepper was inoculated at approximately 8 log cfu/g and stored at 25 and 35 °C at high (97% RH) and ambient (≤40% RH) humidity. At high relative humidity, a_w increased to approximately 0.8–0.9 after approximately 20 days at both temperatures and no Salmonella was detected after 100 and 45 days at 25 and 35 °C, respectively. Under ambient humidity, populations showed an initial decrease of 3–4 log cfu/g, then remained stable for over 8 months at 25 and 35 °C. Results of this study indicate Salmonella can readily grow at permissive a_w in ground black pepper and may persist for an extended period of time under typical storage conditions.     

Effect of sublethal concentrations of propionic or butyric acid on growth and aflatoxin production by Aspergillus flavus

Propionic or butyric acid was added at sublethal doses (0.1–2 mg/ml) to a growth medium supporting growth of Aspergillus flavus and subsequent aflatoxin production. A reduction in growth and aflatoxin production occurred when the acids were added at the time of inoculation. Addition of the acids to cultures at different times resulted in little effect on growth but production of aflatoxin after 12 days was reduced with earlier time of application for both propionic and butyric acid. When the acids were added to rough rice with a moisture content of 21% and inoculated with A. flavus fungal growth and aflatoxin production were reduced relative to non-inoculated controls. Early application of acids resulted in lower yields of aflatoxin.     

Effects of flavorings, storage conditions, and storage time on survival of Staphylococcus aureus in Sürk cheese

The objectives of this study were to determine the cumulative effects of flavorings (chili pepper, thyme, mint, cumin, nutmeg, allspice, clove, cinnamon, black pepper, salt, and hot red pepper paste), storage conditions, and storage time on the survival of Staphylococcus aureus in Sürk cheese and to monitor the associated chemical changes. Sürk cheese, a traditional Turkish cheese, was produced by heating diluted nonfat yogurt and adding flavorings to the resultant acid-heat curd. The cheese was later inoculated with S. aureus, shaped conically, and stored aerobically for mold growth and anaerobically in olive oil for 30 days at room temperature. The moisture content of aerobically stored cheese decreased over time and led to increases in total solids, salt, salt-in-moisture, and ash content during ripening (P < 0.05). The presence or absence of the flavorings had no significant effect, whereas storage conditions and storage duration decreased the survival of S. aureus (P < 0.05).     

Investigation on the toxicity of fungi from rootstock snacks

Chicken embryo bioassay was used to monitor the toxicity of extracts from rootstock snack samples during a 210-day storage period. Results show that the relative toxicity values which were initially very low increased significantly as from 120th day (when 32% mortality was recorded) up till the last day when 73% was obtained. Toxicity of extracts from axenic cultures of 12 fungal species isolated from the snack samples was also determined. The strains of Aspergillus chevalieri, Rhizopus nigricans and Rhizopus sp investigated were nontoxic. A. niger, A. flavus, A.fumigatus, Penicillium chrysogenum, A. parasiticus, P. citrinum, A. ochraceus, Fusarium monifilorme and A. candidus were found to be toxic in decreasing order of potency as recorded after 30 days of growth at room temperature on substrate of 0.90 water activity level. Trends in the moisture content levels, pH and the incidence of fungal growth on the snack samples were also studied. Results suggest that storage for a period not exceeding 90 days and maintenance of safe moisture level would control mould growth and the associated mycotoxins in the snack.     

Combination of digital images and laser light to predict moisture content and color of bell pepper simultaneously during drying

Optical devices are being increasingly used for more accurate and faster ways to investigate quality parameters of agricultural products. The main task of this research is to evaluate the use of a CCD camera in combination with laser diodes emitting at 532 nm and 635 nm to monitor changes in moisture content of red, yellow and green bell pepper during drying. Moreover, the feasibility of using the CCD camera alone to analyze color changes during drying, in alternative to the colorimeter, is assessed. Results showed that scattering area and light intensity were able to predict moisture content changes of bell pepper during drying. While excellent correlations were obtained for yellow colored samples (R = 0.93 and RMSEP = 7.28), the behavior of green and red wavelengths in peppers with red and green color, respectively, may raise some doubt on the ability to predict moisture content (R = 0.33 and RMSEP > 22). Additionally, light scattering varied according to the different depths on the surface where the images were taken. Furthermore, it was concluded that a change in tissue structure during drying may have caused dispersion of photons through the surface resulting in varying degrees of scattering. The presented technique based on a digital camera and laser diodes shows the potential to be applied in the future as a fast and modern method for in-line measurements of monitoring moisture content during drying. Digital images in terms of RGB values have been demonstrated to be a promising alternative to monitor changes of L^∗ (R = 0.87 and R = 0.90), and a^∗ values (R = 0.93 and R = 0.97), during drying of yellow and green pepper. Extensive studies are still required to determine the suitability of digital images for analysis of b^∗ values at different colors of bell pepper.     

Mycological and physical parameters for selecting suitable packaging material for pre- and post-irradiation storage of cereal grains in Ghana

Owing to the rough warehouse handling of storage sacks in tropical areas in Africa, a suitable storage sack should not support de novo growth of fungal spores because this would reduce the tensile strength of the packaging material and act as a springboard for infecting grain contents. This paper reports the effect of activity of saprophytic fungi on the tensile strength of jute and woven polypropylene sacks. New woven polypropylene sacks carried lower levels of fungal spores (1.3×10¹ cfu/72 cm²) than jute sacks (3.0×10³ cfu/72 cm²). The natural mould penetration and growth was examined on sections (4×5 cm) of both jute and woven polypropylene after previous incubation at relative humidities of 55, 60, 65, 70, 75, 80, 90 and 95% for 10 weeks by placing them on Sabouraud's Agar. There was a significant difference (P = 0.05 level of significance) between the higher penetration of mould growth on jute sacks and that obtained on woven polypropylene sacks. Saprophytic fungi (Aspergillus candidus, A. flavus, A. fumigatus, A. niger, A. japonicus, A. parasiticus, A. ustus, Fusarium oxysporium, F. moniliforme, Penicillium verucosum var. cyclopium, Rhizopus oryzae and Trichoderma viride) isolated from jute sacks reduced tensile strength, measured by an Instron Model 1026, by 50–75% after 10 weeks at 90% R.H. Same fungal species on woven polypropylene sacks did not alter the tensile strength. Woven polypropylene sacks did not absorb moisture whilst the moisture content of jute sacks increased by 5.3–6.0% in 10 weeks at 90% R.H. with concomitant increase in mould and yeast counts by 1–2 log cycles. Evidence is presented to show that there was a positive correlation between the final mycoflora on jute sacks and loss in tensile strength. No correlation, however, was found between the total aerobic bacteria on jute sacks and the concomitant reduction in tensile strength. Fungi therefore play a major role in the reduction of tensile strength of jute sacks. Sterilization by gamma irradiation (8.0 kGy) of jute and woven polypropylene sacks did not affect their intrinsic tensile strength. Woven polypropylene sacks therefore have many microbiological and physical advantages over the traditional jute sacks to merit their use for grain storage in tropical areas like Ghana.     

Effect of continuous and intermittent ultrasound on drying time and effective diffusivity during convective drying of apple and red bell pepper

A new approach of ultrasound-assisted convective drying was tested in this study using a screen as product support and sound transmitting surface. Red bell pepper and apple cubes were dried at 70 °C in a laboratory scale hot-air drying oven. In addition to continuous ultrasound used for both products, intermittent ultrasound was applied for apple drying reducing net sonication time to 50% and 10%. Significant improvements of drying characteristics were observed for continuous sonication and intermittent ultrasound at 50% net sonication time. Experimental data were fitted with eight models, among which the Midilli model resulted in the best fit with R² > 0.9988 and reduced χ² ? 0.0002. The influence of ultrasound on drying time to reach 20% and 30% residual moisture content as well as on effective moisture diffusivities and drying periods is discussed.     

Effect of CO2 modified atmosphere packaging on aflatoxin production in maize infested with Sitophilus zeamais

The weevil Sitophilus zeamais (Motschulsky), the maize weevil, is a pest of stored maize that can cause feeding damage and lead to the proliferation of toxigenic fungi. The application of modified atmospheres with a high concentration of CO₂ is an alternative method for the control of S. zeamais and the inhibition of fungal growth. The objectives of the study were to determine the effect of S. zeamais infestation, grain damage and grain moisture content on aflatoxin production by Aspergillus flavus on maize, and the impact of high CO₂ modified atmosphere packaging on pest infestation and aflatoxin production. Mycotoxin production was only recorded when maize was infested with S. zeamais and had A. flavus inoculum. However, production of mycotoxins was not recorded when the maize was mechanically damaged and stored at 18% moisture content, indicating that the biological activity of the insect was determinant in the production of mycotoxins. The high CO₂ modified atmosphere packaging tested (90% CO₂, 5% O₂ and 5% N₂) prevented mycotoxin production.     

Effect of Capsicum annuum (Red Sweet and Cayenne) and Piper nigrum (Black and White) Pepper Powders on the Shelf Life of Fresh Pork Sausages Packaged in Modified Atmosphere

ABSTRACT Capsicum annuum (red sweet and hot cayenne) and Piper nigrum (black and white) pepper powders were evaluated for inhibition of oxidative reactions and extension of the shelf life of fresh pork sausages packaged in a modified atmosphere. Sausages containing either red sweet pepper or cayenne pepper (0.1%, 0.5%, or 2%) or black or white pepper (0.1%, 0.5%, or 1%) were packaged in a modified atmosphere of 80% O₂+ 20% CO₂, stored for 16 d in the dark at 2 °C, and analyzed each 4 d for pH, CIE L*, a*, and b*, 2‐thiobarbituric acid‐reactive substances (TBARS), psychrotrophic aerobes, sensory discoloration, and off‐odor. Results demonstrated that Capsicum peppers (sweet red and hot cayenne) enhanced red color but failed to prevent discoloration, whereas they were very effective in inhibiting lipid oxidation, chiefly at the highest concentration used (2%), which resulted in a delay of off‐odor formation. Piper peppers (black and white) significantly delayed discoloration with small modification of sausage color; furthermore, they also inhibited lipid oxidation, which led to a delay of off‐odor formation, particularly in the form of black pepper. Besides this, all those spices inhibited microbial growth when added at the highest concentration (1%Piper and 2%Capsicum).