Influence of water activity on physical properties, fungal growth, and ochratoxin A production in dry cherries and green‐coffee beans

Abstract

Water activity (aw) influences the growth of fungi as well as the biosynthesis of ochratoxin A (OTA). The objective of this study was to obtain the critical storage conditions at which coffee beans are not susceptible to deteriorative physical changes and quantification of OTA in dry cherries and green‐coffee beans after 60 days of storage at 35°C. aw significantly affected the color, texture, and morphology in dry cherries and in green‐coffee beans after storing. Three different genera of fungi were isolated from coffee samples, Aspergillus, Rhizopus, and Penicillium. The analyzed coffee beans showed a high concentration of OTA (15.49–65.22 μg·kg−1). The conditions at 35°C under which the physical changes and the highest concentration of OTA were found are the following: aw between 0.515 and 0.821. These results suggest that the control of aw during coffee bean storage can be useful to limit OTA formation, whereas the physical properties are maintained. Novelty impact statement Dry cherries showed higher OTA content than green‐coffee beans. In addition, water activity affects the OTA content, color, texture, and morphology in dry cherries and green‐coffee beans. Thus, the control of water activity during coffee bean storage can be useful to limit OTA formation.

Effect of calcium hydroxide on pasting, thermal, and water‐adsorption behavior, and the flow properties of nixtamalized corn flour

“…C and k exhibited values in the range of 23.01–17.62 and 0.73–0.65, respectively. Constant C represents a measure of the attraction force between the water and the adsorption sites in the monolayer, while constant k is a measure of the interaction of the water molecules in the multilayers with the adsorbent (Estrada‐Bahena et al, 2022).…”

“…The GAB monolayer value is considered as the adequate moisture content to enhance food stability and quality. In addition, many works have experimentally confirmed the relationship between the minimum-integral entropy approach and the stability of food products (Domínguez et al, 2007;Estrada-Bahena et al, 2022;Maldonado-Astudillo et al, 2019;Rasc on et al, 2011), because it can be related with the order arrangement of the water molecules adsorbed in NCF. Minimum integral entropy at 25 C for NCF samples is described in Figure 2.…”

“…However, despite the number of studies mentioned, to date there are, to our knowledge, no studies on the thermodynamics function of sorption as well as of the flow properties of NCF. On the one hand, the thermodynamic function of the water adsorption of dried foodstuff provides valuable information regarding the reactivity of adsorbed water to accelerate the appearance of certain deteriorating changes, such as microbial spoilage, oxidative, enzymatic, and non‐enzymatic reactions, and texture alteration (Estrada‐Bahena et al, 2022), which can be employed to predict potential changes in NCF storage stability. On the other hand, powder properties affect the bulk behavior of cereal flours during processing, packing, and handling (Bian et al, 2015).…”

Influence of Saccharomyces boulardii inoculation on post‐harvest processing methods on the coffee quality

“…Previous literature stated that water activity affected the morphology, color, and texture of green coffee beans after storage (Estrada-Bahena et al, 2022). Therefore, it is important to decrease water activity during drying.…”

Influence of Coffee Variety and Processing on the Properties of Parchments as Functional Bioadditives for Biobased Poly(butylene succinate) Composites

“…In dependence of the coffee processing, proper drying is of high relevance to adsorb the free water from the coffee bean and coffee by-products to prevent fungal growth and mycotoxin production. The drying or storage temperatures, moisture content and the water activity a w , an indicator for the amount of free water that is available for microorganism and molecular transformation, are the parameters with the greatest influence on the stability of a food or biogenic by-product [ 13 ]. For green coffee beans, a water activity a w < 0.80 has shown no fungal growth and should therefore not be exceeded [ 14 ].…”