Monitoring the process to obtain red wine enriched in resveratrol and piceatannol without quality loss

Stilbene-enriched wine is considered an interesting new food product with added value as a consequence of the numerous health-promoting properties ascribed to it, mainly from its trans-resveratrol content. Postharvest grapes have been treated with ultraviolet-C light to produce stilbene-enriched grapes that were later used in a conventional winemaking process to obtain a red wine enriched in stilbenes.     

The use and profitability of hermetic technologies for grain storage among smallholder farmers in eastern Kenya

Hermetic storage technologies (HSTs) have been disseminated in Sub-Saharan Africa (including Kenya) to reduce grain storage losses among farmers. We carried out a study in three counties in eastern Kenya to assess the use and profitability of HSTs among farmers. Data were collected from 613 farmers using a semi-structured questionnaire and Kobo Toolbox via android tablets. Results showed an increase in use of HSTs among farmers from 53.7% in 2015 to 91.2% in 2017. PICS was the most used hermetic bags by farmers (84%) in 2017. Majority of farmers (73.5%) received training in the use of HSTs from extension agents and agro-dealers. About 40% of respondents purchased additional (one to five) bags after their first experience using them. The quantity of grain produced made up about half of the farmer’s decision to store. The primary reason (87%) farmers used hermetic bags was the need to manage insect pests. Maize and beans were the most produced and most stored crops; but maize was the most stored in HST. Grain price seasonality showed a near doubling effect between the lean and harvest seasons. Estimates of the return on investments (ROI) ranged between 13 and 80% for all crops and maize stored in hermetic bags had the highest ROI. Awareness and trainings are key in increasing adoption and proper use of HSTs.     

中华寿桃采后生理的研究

本论文以中华寿桃为试验材料,研究了不同贮藏条件对中华寿桃的冰点、呼吸强度、VC含量、相对电导率、PPO等品质和生理指标的影响.并探讨了中华寿桃软化衰老的生理机制,为中华寿桃的贮藏保鲜提供了理论依据.     

冬枣采后生理及贮藏技术研究

研究了不同温度和不同气体条件下冬枣的贮藏效果，不同温度下枣果实呼吸强度的变化，以及在贮藏期间枣果实Vc、总糖、乙醇、丙二醛(MDA)含量的变化。结果表明：冬枣采后呼吸强度很高，但属于非呼吸跃变型果实；随着贮藏期的延长，枣果Vc含量逐渐减少，总糖含量前期升高，中后期逐渐下降，乙醇和MDA含量逐渐升高；低温气调贮藏效果明显好于单纯的冷藏，气调贮藏对提高Vc的保存率、保护细胞膜系统、延缓果实衰老有明显的作用，并不会加重枣果实的无氧呼吸而使乙醇生成量增加。     

Application of Drying Technology to Control Aflatoxins in Foods and Feeds: A Review

Aflatoxins are secondary metabolites produced by certain species of Aspergillus, i.e., A. flavus, A. parasiticus, and the rare A. nomius, during their growth under favorable conditions of temperature and humidity. Aflatoxins are highly toxic compounds, which can cause acute and chronic toxicity in humans and animals. The incidence of aflatoxins in foods and feeds is relatively high in tropical and subtropical regions, where the warm and humid weather provides optimal condition for the growth of molds. As aflatoxins are very heat stable and cannot be easily eliminated by domestic cooking, rapid drying of agricultural products to reduce their moisture content is important, as this can avoid the favorable conditions for the growth of fungi. This article reviews general information on aflatoxins, products prone to be contaminated with aflatoxins, and the use of different drying techniques to control mold growth and aflatoxins production, as well as to reduce the contamination level of aflatoxins in food products.     

Microwave Finish Drying of Osmotically Dehydrated Cranberries

Combined microwave and hot-air drying characteristics was studied for the drying of cranberries that had been previously partially dehydrated by osmosis in a high fructose corn syrup (76°Brix). A 750 W 2450 MHz microwave oven was used to dry cranberry samples from 57% to 15% moisture content using three different power densities (0.75, 1.0, 1.25 W/g of initial cranberries) and two different power cycles (30 s On/30 s Off and 30 s On/60 s Off). All combinations of these variables were tested in triplicate. Quality of the cranberries was measured using a universal testing machine, chromameter, and with the use of a taste test panel. Drying times ranged from 2.2 to 5.0 h. Power times and power cycles affected the drying time and the quality of the dried cranberries. Lower power densities resulted in cranberries with higher quality. High power densities (125 W/g) resulted in the burning of some cranberries.     

Effect of beeswax content on hydroxypropyl methylcellulose-based edible film properties and postharvest quality of coated plums (Cv. Angeleno)

The effect of beeswax (BW) content of hydroxypropyl methylcellulose (HPMC)–BW edible coatings on stand-alone film properties and on postharvest quality of coated ‘Angeleno’ plums was studied. The coatings contained BW at 4 lipid content levels (0, 20, 40 and 60 g/100 g, dry basis). Coated and uncoated plums were stored 4 weeks at 1 °C and transferred to 20 °C for 1–3 weeks. Addition of BW to the HPMC film matrix reduced film mechanical resistance and oxygen barrier, and improved film moisture barrier. Film mechanical properties showed a good fit with an exponential and/or linear model that could provide a useful tool to predict mechanical properties with others HPMC–BW composition mixtures. Coatings with BW reduced plum weight loss compared to HPMC-based coatings with no BW. Plum weight loss decreased as BW content increased from 20 to 40 g/100 g, but above 40 g/100 g BW content, weight loss was not further reduced. Whereas, water vapor permeability of stand-alone films decreased significantly as BW content increased to 60 g/100 g. Coatings reduced plum softening and bleeding, with those with lower BW content being more effective, which could be related to the ability of coatings to create a modified atmosphere in the fruit. Flavor was not affected by coating application. Results indicate that HPMC–BW coatings with 20 g/100 g BW would provide the best compromise to extend shelf life of ‘Angeleno’ plums.     

Pasteurization process development for controlling Salmonella in in-shell almonds using radio frequency energy

Radio frequency (RF) treatment holds potential as a pasteurization method to control Salmonella in almonds without causing a substantial loss of product quality. Thermal resistance of Salmonella can be reduced by increasing water activity, thus a soaking process was designed prior to RF treatments. A pilot-scale 27 MHz, 6 kW RF heating system was used to rapidly heat 1.7 kg washed in-shell almonds with hot air heating at 55 °C. To achieve appropriate heating rate, constant drying temperature and short time cooling, the RF treatment protocol was obtained using an electrode gap of 13 cm for heating, 14 cm for drying, and followed by forced room air cooling of 5-cm thick samples. The results showed that almond temperatures above 75 °C at 23% moisture contents for 2-4 min RF heating could meet the requirements to achieve 5-log reduction of Salmonella. The RF treatment process for 20 min reduced the moisture content to 5.7% w.b. Peroxide value, fatty acids values and kernel colors of the RF treated almonds met good quality standard used by nut industry.     

The effect of small leaks,grain bulk,and the patching of leaks on the performance of hermetic storage

Hermetic storage containers are often used by farmers to protect their harvested grain from insect damage and ultimately stop insect population development. Sometimes holes in a storage container are created by insects or by accident; such holes may reduce the effectiveness of the hermetic storage unit. Using cowpea grain and the cowpea bruchid, Callosobruchus maculatus (F), we investigated the degree to which holes in a hermetic storage container wall affect the level of grain damage. When there were low numbers of holes, seed damage increased markedly with each additional hole. The grain itself contributed a barrier to oxygen diffusion through the grain mass. If holes in the container wall were patched with a single layer of HDPE film, grain damage was indistinguishable from that seen under full hermetic conditions. We provide evidence that a single layer of woven polypropylene contributes a small but measurable barrier to oxygen penetration into the container.     

The dry chain: Reducing postharvest losses and improving food safety in humid climates

BackgroundEven as increasing populations put pressure on food supplies, about one-third of the total food produced for human consumption is wasted, with the majority of loss in developing countries occurring between harvest and the consumer. Controlling product dryness is the most critical factor for maintaining quality in stored non-perishable foods. The high relative humidity prevalent in humid climates elevates the moisture content of dried commodities stored in porous woven bags, enabling fungal and insect infestations. Mycotoxins (e.g., aflatoxin) produced by fungi in insufficiently dried food commodities affect 4.5 billion people worldwide.Scope and approachWe introduce the term “dry chain” to describe initial dehydration of durable commodities to levels preventing fungal growth followed by storage in moisture-proof containers. This is analogous to the “cold chain” in which continuous refrigeration is used to preserve quality in the fresh produce industry. However, in the case of the dry chain, no further equipment or energy input is required to maintain product quality after initial drying as long as the integrity of the storage container is preserved. In some locations/seasons, only packaging is required to implement a “climate smart” dry chain, while in humid conditions, additional drying is required and desiccant-based drying methods have unique advantages.Key findings and conclusionsWe propose both climate-based and drying-based approaches to implement the dry chain to minimize mycotoxin accumulation and insect infestations in dry products, reduce food loss, improve food quality, safety and security, and protect public health.