A review of varietal change in roots,tubers and bananas: consumer preferences and other drivers of adoption and implications for breeding

This review of the literature on varietal change in sub-Saharan Africa looks in detail at adoption of new varieties of bananas in Uganda, cassava in Nigeria, potato in Kenya, sweetpotato in Uganda and yams in Côte d’Ivoire. The review explored three hypotheses about drivers of varietal change. There was a strong confirmation for the hypothesis that insufficient priority given to consumer-preferred traits by breeding programmes contributes to the limited uptake of modern varieties (MVs) and low varietal turnover. Lack of evidence meant the second hypothesis of insufficient attention to understanding and responding to gender differences in consumer preferences for quality and post-harvest traits was unresolved. The evidence on the third hypothesis about the informal seed system contributing to slow uptake of MVs was mixed. In some cases, the informal system has contributed to rapid uptake of MVs, but often it appears to be a barrier with inconsistent varietal naming a major challenge.     

Systematic literature review shows that appetite rating does not predict energy intake

Ratings of appetite are commonly used to assess appetite modification following an intervention. Subjectively rated appetite is a widely employed proxy measure for energy intake (EI), measurement of which requires greater time and resources. However, the validity of appetite as a reliable predictor of EI has not yet been reviewed systematically. This literature search identified studies that quantified both appetite ratings and EI. Outcomes were predefined as: (1) agreement between self-reported appetite scores and EI; (2) no agreement between self-reported appetitescores and EI. The presence of direct statistical comparison between the endpoints, intervention type and study population were also recorded. 462 papers were included in this review. Appetite scores failed to correspond with EI in 51.3% of the total studies. Only 6% of all studies evaluated here reported a direct statistical comparison between appetite scores and EI. χ² analysis demonstrated that any relationship between EI and appetite was independent of study type stratification by age, gender or sample size. The very substantive corpus reviewed allows us to conclude that self-reported appetite ratings of appetite do not reliably predict EI. Caution should be exercised when drawing conclusions based from self-reported appetite scores in relation to prospective EI.     

Future developments in assisted reproduction in humans

The advent of human in vitro fertilization (IVF) over 30 years ago has made the oocyte and preimplantation embryo uniquely accessible. This accessibility has given rise to new micromanipulation techniques, such as intracytoplasmic sperm injection for treatment of male infertility, as well as embryo biopsy for preimplantation diagnosis of both genetic disease and aneuploidy, a major cause of early embryo demise and miscarriage. In the UK, average pregnancy rates after IVF and embryo transfer are < 25%, even after transfer of several embryos. Unfortunately, a third of these pregnancies involve multiple gestations. Research is currently focusing on methods to improve IVF success rates while reducing twin and triplet pregnancies and their associated increased morbidity and mortality. One approach is to develop screening methods to identify the most viable embryos, so that transfer of fewer healthy embryos will result in a higher proportion of singleton pregnancies. Screening methods include optimizing culture conditions for prolonged culture and selection of viable blastocysts for transfer, or embryo biopsy and aneuploidy screening. Assisted reproduction is also increasingly important in other branches of medicine: survival rates for cancer sufferers are improving continually and there is now a significant need for approaches to preserve fertility after sterilizing chemo-and radiotherapy treatment. Techniques for cryopreserving male and female gametes or gonadal tissue are being developed, although systems to grow and mature these gametes are in their infancy. Finally, there are also concerns regarding the safety of these new assisted reproductive technologies.     

Isolation and characterization of a psychrotolerant toxin producer, Bacillus weihenstephanensis, in liquid egg products

A psychrotolerant bacteria of the Bacillus cereus group was found responsible for the spoilage of whole liquid egg products. By sequencing a 16S rRNA region and performing a PCR amplification of specific 16S rRNA and cspA signatures, a Bacillus weihenstephanensis was identified. Characterization of this strain shows its ability to grow in defined medium as well as in whole liquid egg at refrigerated temperatures. The strain isolated possesses genes encoding for hemolysin BL, nonhemolytic enterotoxin, and B. cereus enterotoxins and produces enterotoxins with cytotoxic activity in whole liquid egg, even at refrigerated temperatures. The isolate exhibits a clear ability to stick and form biofilms on stainless steel, the most common material used in egg breaking factories, as well as on model hydrophilic (glass) and hydrophobic (polytetrafluoroethylene) materials. These findings show the necessity to monitor for Bacillus contamination in egg products that are often used in the composition of particularly susceptible finished products such as cream, dessert, dairy, meat, and seafood.     

Antimicrobial Activity of Nisin and Natamycin Incorporated Sodium Caseinate Extrusion‐Blown Films: A Comparative Study with Heat‐Pressed/Solution Cast Films

Antimicrobial edible films based on sodium caseinate, glycerol, and 2 food preservatives (nisin or natamycin) were prepared by classical thermomechanical processes. Food preservatives were compounded (at 65 °C for 2.5 min) with sodium caseinate in a twin‐screw extruder. Anti‐Listeria activity assays revealed a partial inactivation of nisin following compounding. Thermoplastic pellets containing food preservatives were then used to manufacture films either by blown‐film extrusion process or by heat‐press. After 24 h of incubation on agar plates, the diameters of K. rhizophila growth inhibition zones around nisin‐incorporated films prepared by solution casting (control), extrusion blowing or heat pressing at 80 °C for 7 min of nisin‐containing pellets were 15.5 ± 0.9, 9.8 ± 0.2, and 8.6 ± 1.0 mm, respectively. Since heat‐pressing for 7 min at 80 °C of nisin‐incorporated pellets did not further inactivate nisin, this indicates that nisin inactivation during extrusion‐blowing was limited. Moreover, the lower diameter of the K. rhizophila growth inhibition zone around films prepared with nisin‐containing pellets compared to that observed around films directly prepared by solution casting confirms that nisin inactivation mainly occurred during the compounding step. Natamycin‐containing thermoplastic films inhibited Aspergillus niger growth; however, by contrast with nisin‐containing films, heat‐pressed films had higher inhibition zone diameters than blown films, therefore suggesting a partial inactivation of natamycin during extrusion‐blowing.     

Characterization of Carnobacterium maltaromaticum LMA 28 for its positive technological role in soft cheese making

Carnobacterium maltaromaticum is a lactic acid bacterium isolated from soft cheese. The objective of this work was to study its potential positive impact when used in cheese technology. Phenotypic and genotypic characterization of six strains of C. maltaromaticum showed that they belong to different phylogenetic groups. Although these strains lacked the ability to coagulate milk quickly, they were acidotolerant. They did not affect the coagulation capacity of starter lactic acid bacteria, Lactococcus lactis and Streptococcus thermophilus, used in dairy industry. The impact of C. maltaromaticum LMA 28 on bacterial flora of cheese revealed a significant decrease of Psychrobacter sp. concentration, which might be responsible for cheese aging phenomena. An experimental plan was carried out to unravel the mechanism of inhibition of Psychrobacter sp. and Listeria monocytogenes and possible interaction between various factors (cell concentration, NaCl, pH and incubation time). Cellular concentration of C. maltaromaticum LMA 28 was found to be the main factor involved in the inhibition of Psychrobacter sp. and L. monocytogenes.     

Uptake of Tritiated Liquids by Individual Breakfast Cereal Flakes

ABSTRACT: Surface liquid adhesion (SLA) and liquid absorption (LA) of tritiated liquids, including water and skim, low-fat, whole, and fat-enriched milks, by cornflakes (CF) and frosted flakes (FF) were determined by scintillation counting using water-[³H] at 0.5 μCi/mL. SLA or the liquid adhering to individual flakes after a short immersion period was the same for CF and FF in the case of water (approximately 0.011 μL mm⁻² of flake) but were always higher for CF than for FF and increased as the fat content in milks augmented. LA of individual flakes, followed for 300 s of soaking, increased with time and was always higher for CF than for FF (for the same liquid), however, data did not follow a regular pattern. Flakes showed quite compact outer surfaces and an internal porous matrix composed of air cells of various sizes separated by dense walls of different thicknesses. This heterogeneous microstructure of individual flakes may be the cause of the lack of a simple kinetics during the soaking process. Previous results obtained by soaking a mass of flakes overestimated the uptake of fluid by individual because they included the liquid occluded between the flakes.